So, you're beginning your collection of effects pedals and are wondering if it's okay to leave them turned on when they're not in use.

Is it bad/damaging to keep effects pedals on when not in use? Keeping an effects pedal on/powered when it's not in use is typically safe, though it may decrease its overall longevity. If batteries are used for power, they'll be drained. If a power block or daisy chain is used for power, random/accidental power surges increase the risk of damage.

In this article, we'll discuss the multiple reasons why leaving effects pedals powered/on isn't optimal. Though the focus will be on the overall lifespan of the pedals, I'll briefly touch on the slight but notable economic and environmental impacts.

With that, let's get into this article to help you take better care of your music and audio equipment.

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

A Primer On Effects Pedals & Power

Before we begin our discussion on keeping pedals powered when they're not in use, let's briefly go over why effects pedals need power in the first place.

Please feel free to skip ahead to the section Why Leaving Effects Pedals On/Powered Is A Bad Idea if you wish.

Put simply, effects pedals require power for their active components. Active components range from transistors, operational amplifiers, integrated circuit chips and diodes to the LED indicator lights that tell us whether the pedal is on or off.

These active components are required to effectively produce the effect(s) the pedal is designed for. They also help route the signal, buffer it (adjust impedance) and otherwise maintain adequate signal strength.

Note that there are some passive pedals on the market, but they are rare. In the vast majority of cases, pedals will require power.

Most pedals require 9V (9-volt) power, hence why many pedals have 9V battery compartments. 12V, 18V and 24V are other voltage requirements you may encounter. It's important that we power these pedals with proper power supplies/adapters (wall warts, power blocks, etc.) that match their voltage requirements.

Similarly, pedals will draw a defined amount of electrical current (measured in milliamps “mA”). We must ensure that the power supply can provide as much or more current for the pedal.

A battery will cover these bases, as will the proper adapter for a given pedal. If you decide to daisy chain pedals together, ensure there's enough current to cover all the pedals' current needs.

Additionally, it's worth noting the polarity of the pedal. This refers to whether the centre pin of the pedal's power input is positive or negative. Most guitar pedals will have a negative center pin, but it's worth double-checking to ensure the polarity of the pedal and power source match.

Pedals will draw power when effectively “plugged in,” either via the audio input and/or output connection. Power must be drawn while the pedal is turned on, but it's also necessary when the pedal is bypassed (in true and buffered bypass designs).

To learn more about true and buffered bypass, check out my article What Does ‘True Bypass’ Mean In A Guitar Pedal?

If not, the momentary power-up time as a pedal is switched on/off will have ill effects on the pedal's performance, including short-lived silence, distortion, and even transient clips/pops in the guitar signal. Having constant power is essential for smooth transitions between engaging and disengaging the pedal.

Before we wrap this primer up, let's consider the common methods for powering effects pedals:

• Batteries
• DC adapters “wall warts”
• Daisy chaining
• Dedicated power supply

Powering Effects Pedals With Batteries

Many pedals can be powered by batteries. These pedals will have battery compartments built into their housing. Most often, these will be 9V batteries (since 9V is such a common voltage requirement among pedals).

Some pedals will have alternate battery requirements (the Line 6 DL4 takes four DD batteries, for example). Some smaller pedals may not have an option for batteries whatsoever.

In most designs, the battery will be tapped into so long as the audio input (1/4″ jack) is plugged into. Other designs require the output or both the input and output to be connected. In many designs, the battery will be disengaged once the power input is plugged into.

Note that batteries corrode over time, and I wouldn't recommend storing pedals for any length of time with batteries. I had issues with my own DL4 (mentioned above) after storing it for a few months with corroding DD batteries.

Line 6 is featured in My New Microphone's Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.

Powering Effects Pedals With DC Adapter

Many pedals will come with their own dedicated DC adapter, commonly referred to as a “wall-wart.” These adapters connect to the wall sockets and adapt the power mains (in voltage and current) for their particular pedal. Their polarity is, of course, matched to the pedal's polarity design.

These adapters are great for a pedal or two but become cumbersome when dealing with multiple pedals due to the need for an individual socket for each pedal.

Powering Effects Pedals With Daisy Chaining

Daisy-chaining allows one wall wart to power multiple pedals in a row. This takes up less space and requires fewer wall sockets to get power to the pedals.

All the pedals within a single daisy chain must have the same voltage requirements to work together. Additionally, the power source must supply enough current to power all pedals.

Remember that each pedal will draw its own current, so the power source of a daisy chain must be able to supply as much or more current as the sum of all the pedals' current requirements.

Powering Effects Pedals With Dedicated Power Supply

Dedicated pedal power supplies/blocks have isolated connections. Essentially, each DC output of a power block is its own circuit. This cleans up noise between pedals in the power circuit (though there will likely still be noise in the audio signal chain). It also allows a single power supply unit to power pedals with various power requirements.

With that long primer, let's get into the main part of the article.

Why Leaving Effects Pedals On/Powered Is A Bad Idea

Leaving pedals on when not in use isn't ideal. However, it's not the end of the world if you forget to turn them off now and again. That being said, turning the pedals off (unplugging them) is generally a good habit to develop.

Note that by “on/powered,” I mean the pedal is drawing power. As mentioned above, most pedals will draw power so long as their audio input jack is plugged into. Pedals do not only draw power when they are engaged!

There are three primary reasons why leaving effects pedals on isn't ideal:

• Battery drain
• Heat
• Potential power surges

Battery Drain

So long as the pedal is plugged in and relying on batteries for its power, the batteries will be draining.

Remember that, for most pedals, the pedal draws power as soon as the audio input is plugged into. If the pedal isn't connected to a dedicated adapter-type power source, it will draw power from the battery.

So then, keeping a pedal powered will drain its battery. There's no need to continue draining the battery when the pedal isn't in use, so unplugging the pedal is a good idea.

Furthermore, as batteries drain, their voltage slowly drops. There will, of course, be a point where the voltage is too low to power the pedal. However, there will also be a range in which the battery underpowers the pedal, thereby causing the pedal to work at a limited capacity. This will likely alter the signal strength and the actual intended effect of the pedal.

Potential Power Surges

Electrical surges, outages, and brownouts will cause abrupt disengagement of power and large transient spikes as the power is restored. These occurrences are risky and could cause significant damage to the circuitry of the effects pedals if they're connected to the power mains (via their power adapters).

If the pedals are disconnected from power (or powered via batteries), power surges will not have this damaging effect. Avoid this potential issue by disconnecting the pedals when they're not in use.

Of course, power surges can happen when the pedals are in use as well. This is a risk we take regularly. Many dedicated pedal power supplies offer surge protection to add an additional layer of safety for their connected pedals.

Heat

Heat is another concern when powering effects pedals—leaving pedals on while not in use keeps them heated. Furthermore, you can even prevent them from cooling after each use, which could help protect their circuits.

Of course, pedals are built tough (they're known as “stompboxes,” after all). They're often resistant to physical abuse, humidity and heat. However, running electronics hot can potentially reduce their lifespan.

It Is Bad For Your Pocket

Second in line, after being bad for the pedals themselves, is that leaving the pedals powered/on is also bad for your wallet. Though electricity is relatively affordable in most places, it still costs money. Leaving devices on will increase the power bill. Some gear consumes more electric power than others, but they all do when left on.

Idle Power Consumption Is An Issue Worth Addressing

According to a recent study by the Stanford Sustainable Systems Lab, the idle load of homes constitutes 32% of the entire household electricity consumption in the US. That's a lot of wasted energy.

Expanding further, we could save the planet some electricity-generating efforts with simple everyday changes like disconnecting our pedals when they're not in use. All the idle power being wasted must be generated by some other means, some of which are unsustainable.

Conclusion

Leaving effects pedals on when not in use might seem insignificant, but it does add to the bigger picture. For starters, it reduces the lifespan of your gear with heat and hours of use. Secondly, it hurts your pocket because you'll have to replace the equipment sooner and pay for extra electricity.

So, now you know, disconnect your pedals from power before you walk out of the practice space. Even better, consider powering down all the other audio equipment that doesn't absolutely need to be on.

The post Is It Bad/Damaging To Keep Effects Pedals On Or Plugged In? first appeared on My New Microphone and is written by Arthur Fox.

So you're wondering which effects pedal you should buy, rent or otherwise try out. In this comprehensive buyer's guide, we'll go through everything worth considering before you make any decisions about an effects pedal.

If you've found yourself asking, “Which pedal/stompbox should I buy?” this extensive resource is for you.

Please feel free to jump around this article and read all the additional resources I have provided links to.

Let's get into this comprehensive effects pedal buyer's guide to help you in your next pedal purchase!

Related articles:
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use
• Top 11 Best Boutique Guitar/Bass Pedal Brands To Know & Use
• Effects Pedals Database
• Effects Pedals Brands Database

Table Of Contents

• What Is Your Effect Pedal Budget?
• Single-Effect Pedals Vs. Multi-Effect Pedals
• Understanding Pedal Types & Effects
  • Dynamic Effects
  • Pitch-Effects
  • Gain-Based-Effects
  • Spectral Effects
  • Modulation Effects
  • Time-Based Effects
  • Utilities
  • Synth Pedals
  • Miscellaneous Effects
• Mono Vs. Stereo Effect Pedals
• True Bypass Vs. Buffered Bypass Pedals
• Planning Out The Pedalboard
• Know The Additional Costs Of Effect Pedal Accessories
• Best Pedals By Type

What Is Your Effect Pedal Budget?

The first thing to consider when making any purchase is your budget. Money can be a touchy subject for some, so I'll keep this section brief.

I would never advise anyone to overspend on any audio equipment. Know what you can realistically afford, and do your best to stay within those limitations, whatever they may be.

Effects pedals, like many audio devices, range significantly in price. The market is rather large, and so there should be a good selection for any budget.

Note that some retailers offer payment plans, which could be an option.

Consider the cost-to-benefit ratio of the purchase of the effects pedal. For example, if the pedal is needed for business, perhaps stretching the budget is more appropriate. On the other hand, if you don't plan on making money with the pedal, perhaps a more conservative budget is appropriate.

Also, consider any additional accessories or upkeep that may be required for your pedal(s).

Only you can determine your budget. All I'm here to say is that you should consider it.

Back to the Table Of Contents.

Single-Effect Pedals Vs. Multi-Effect Pedals

Before we begin searching for our next pedal, we should ask ourselves whether we want an all-in-one multi-effects unit or one or more single-effect pedals.

The difference is in the name. Single-effect pedals (sometimes referred to as stompboxes) are specialized units that focus, typically, on one effect, though some stompboxes offer a few different effects. Conversely, multi-effects pedal units are designed to offer all the effects we would need in a single unit.

Single-effect pedals are typically analogue, though many have digital components. They do one effect well (if designed correctly) and can be chained together with other single-effect pedals according to the musician's needs. Note that each pedal will require its own power supply.

Multi-effects pedals are typically fully digital to pack all the different effects and routings into a single housing. So, with a single unit and a single power supply, the musician has access to a wide variety of effects.

So then, which should you buy? Let's look at the pros and cons lists for each pedal style to help you decide:

Pros Of Single-Effect Pedals

Single-effect pedals are generally easy to use. There are rarely large menus and banks to scroll through, nor are there in-pedal routing issues to solve. That being said, some pedals offer presets.

Single-effect pedals are more visually laid out on pedalboards, and it's easier to see which pedals are on/off and turn them on/off.

Single-effect pedals are easily mounted to pedalboards.

Single-effect pedals are easy to route manually. It's simple to physically move and repatch the pedals to obtain a new signal path.

Cons Of Single-Effect Pedals

Single-effect pedals need to be individually powered, which will eat up batteries quickly (if you go that route, which I don't recommend) or require a dedicated power supply. Powering multiple pedals will require a power brick.

Chaining too many single-effect pedals together can lead to tone suck, where signal degradation becomes a factor in your tone. Additionally, the more pedals that are chained together, the more opportunity there is for something in the chain to go wrong (poor connection, dirty potentiometer, malfunctioning pedal, etc.).

Including too many single-effect pedals on a pedalboard will make it heavy. By the same token, pedalboards have limited space, so they can only fit so many individual effects. Furthermore, having too many pedals can make it difficult to “tap dance” around and ensure the proper pedals are being turned on or off appropriately.

Single-effect pedals only provide one effect or a few at best. Experimenting with new effects would require renting or investing in a new pedal. Buying individual pedals is also less cost-effective than opting for an all-in-one multi-effect.

• Click here to check out single-effect pedals at Sweetwater
• Click here to check out single-effect pedals at B&H Photo/Video
• Click here to check out single-effect pedals on Amazon

Pros Of Multi-Effect Pedals

Multi-effect pedals offer a wide assortment of effects in a single compact unit. They will also often have multiple varieties of any given effect (different flavours of fuzz, a plethora of delay options, etc.). Additionally, multi-effect pedals only require one power supply.

Once understood, the sometimes intimidating menus can be your best friends, offering plentiful options in routing and effects.

Experimenting with lesser-used effects is easy. There's no need to buy a new pedal to try out a new effect that may or may not be used in your tone palette.

Cons Of Multi-Effect Pedals

The menus of multi-effects pedals are sometimes difficult to use. Adjusting things on the fly during a gig is more difficult as options are often hidden in layers of menus rather than being laid out in individual effects units.

Having too many options may be overwhelming.

The presets are great but may not offer the tone you're looking for. However, tweaking these presets is typically possible.

Multi-effects pedals generally don't sound as great at any specific effect as a dedicated single-effect pedal would.

• Click here to check out multi-effect pedals at Sweetwater
• Click here to check out multi-effect pedals at B&H Photo/Video
• Click here to check out multi-effect pedals on Amazon

Back to the Table Of Contents.

Understanding Pedal Types & Effects

Knowing the different effects available in pedals is important. This is true of multi-effect pedals but especially for single-effect pedals.

With so many audio effects, choosing the next effect for your setup can be overwhelming. To make matters even more complicated, there are plenty of pedals on the market for most effects types. Perhaps this is another reason to opt for a multi-effect pedal unit. However, in this section, we'll go through the various pedal effects we'll encounter.

Effects can be categorized into the following broad types:

• Dynamic Effects
• Pitch Effects
• Gain-Based Effects
• Spectral Effects
• Modulation Effects
• Time-Based Effects
• Utilities
• Synth
• Miscellaneous Effects

Related article: Full List & Description Of Guitar Pedal Types

Dynamic Effects

Dynamic effects pedals alter the dynamics of an audio signal (the changes in amplitude over time).

By altering the signal's amplitude, dynamic effects will also alter the shape of the signal waveform, which is, by definition, signal distortion.

The dynamic effects found in pedals include:

• Compressor Pedals
• Limiter Pedals
• Expander Pedals
• Noise Gate Pedals

Compressor Pedals

What is audio compression? Dynamic range compression is the process of reducing the dynamic range of an audio signal by attenuating the amplitude of the signal above a set threshold. A compressor can be software or hardware and performs compression on an audio signal (digital or analog).

Compressors will help fatten the tone by reducing dynamic range. They can also improve sustain and make a musician's levels more consistent.

The types of compressor circuits in compressor pedal circuits are typically VCA, but there are also FET and optical options. Click the links for more information on each compressor type.

When choosing a compressor pedal, listen to the tone and look for the following controls (I've included links to in-depth articles on select controls):

• Output level
• Input level
• Mix
• Threshold
• Ratio
• Attack
• Release
• Sustain
• Tone

• Click here to check out compressor pedals at Sweetwater
• Click here to check out compressor pedals at B&H Photo/Video
• Click here to check out compressor pedals on Amazon

To learn more about compressor pedals, check out the following My New Microphone article:
• What Are Compressor Pedals (Guitar/Bass) & How Do They Work?

Limiter Pedals

What is audio limiting? Limiting is a type of hard compression whereby the signal is not allowed above a certain threshold. Rather than attenuating the signal (above the threshold) by a ratio, the limiter will simply cut off the signal at the threshold. We can think of a limiter as a compressor with an infinite ratio.

Limiter pedals keep the audio signal below a defined maximum output. When hit hard, they act as compressors and sustainers. Hit them even harder, and they may even border distortion and fuzz.

• Click here to check out limiter pedals at Sweetwater
• Click here to check out limiter pedals at B&H Photo/Video
• Click here to check out limiter pedals on Amazon

Expander Pedals

What is audio expanding? Expanding can be thought of as the opposite of compression. It aims to increase the dynamic range of the signal. An expander will reduce the signal's amplitude if it drops below the set threshold, thereby “expanding” the signal’s dynamic range.

Expander pedals aren't that common. However, there is a market for them with players that want extra transients in their tone.

Noise Gate Pedals

What is audio noise gating? Noise gating is an effect that kills the output signal if the input signal drops below a set threshold. This helps to gate or remove noise from the signal when an instrument (or another sound source) is not playing. Noise gates are especially useful in noisy rigs, which often include vintage gear.

Noise gate pedals can be our best friends or our worst enemies. They work by effectively muting the signal below a certain threshold. These pedals help reduce noise and feedback when we're not playing. However, if they're set too sensitive, they can cut the audio before the sustain has a chance to fade appropriately.

When choosing a noise gate pedal, listen to how it cuts in and out below the set threshold, check to see whether there's a send/return insert loop, and look for the following controls:

• Threshold
• Decay
• Reduction

• Click here to check out noise gate pedals at Sweetwater
• Click here to check out noise gate pedals at B&H Photo/Video
• Click here to check out noise gate pedals on Amazon

Pitch Effects

Pitch effects alter or otherwise manipulate the perceived pitch of the incoming audio signal. The two types of pitch-shifting pedals are:

• Pitch-Shifting Pedals
• Octave & Harmonizer Pedals

Pitch-Shifting Pedals

What is pitch-shifting? Pitch-shifting, as the name suggests, is an audio effect that shifts the input signal's pitch.

• Click here to check out pitch-shifting pedals at Sweetwater
• Click here to check out pitch-shifting pedals at B&H Photo/Video
• Click here to check out pitch-shifting pedals on Amazon

To learn more about pitch-shifting pedals, check out my article What Are Pitch-Shifting Guitar Pedals & How Do They Work?

Octave & Harmonizer Pedals

What are octaves? An octave is an interval between one musical pitch and another with double its fundamental frequency. Octave pedals will copy the input signal and pitch the copy/copies up or down an octave(s).

What is harmonization? Harmonization is defined as the chordal accompaniment to a melody. As an effect, harmonization will produce an interval (or multiple intervals) of the inputted note along with the dry signal. Harmonizers can be tuned to certain keys or certain intervals.

With harmonization and octave pedals, the dry note is duplicated one or more times and shifted in pitch. The output is then a combination of the input dry signal and/or a combination of the pitch-shifted voices.

• Click here to check out octave pedals at Sweetwater
• Click here to check out harmonizer pedals at Sweetwater
• Click here to check out octave pedals at B&H Photo/Video
• Click here to check out harmonizer pedals at B&H Photo/Video
• Click here to check out octave pedals on Amazon
• Click here to check out harmonizer pedals on Amazon

Gain-Based Effects

Gain-based effects alter the gain of the signal in one way or another to achieve the desired effect. These effects range from boosting the signal level to clipping it into square wave territory.

The gain-based effect pedals include the following:

• Preamp Pedals
• Boost Pedals
• Overdrive Pedals
• Distortion Pedals
• Fuzz Pedals

Preamp Pedals

What is preamplification? Preamplification is a gain stage where the audio signal is amplified to a level for processing and improved noise tolerance. The preamp in a pedal can typically be overdriven to add saturation/compression/distortion to the signal through some preamps that provide very clean gain.

Preamp pedals are designed to bring a signal level up to a certain point. They work well when left in the on position.

• Click here to check out preamp pedals at Sweetwater
• Click here to check out preamp pedals at B&H Photo/Video
• Click here to check out preamp pedals on Amazon

Boost Pedals

What is boost? Boost is practically the same thing as preamplification. Boost amplifies the signal with clean gain to “boost” the level of the signal without adding any colouration.

A good boost pedal should afford us some extra gain for the parts of playing that require it (solos, etc.). The gain should be clean, though some boost pedals offer some tone control as well.

• Click here to check out boost pedals at Sweetwater
• Click here to check out boost pedals at B&H Photo/Video
• Click here to check out boost pedals on Amazon

Overdrive Pedals

What is overdrive? Overdrive happens naturally when a signal is amplified just past its clean gain limits. Past this point, the peaks/troughs of the instrument signal are compressed and “soft-clipped,” resulting in warm saturation in the signal. The overdrive circuit is designed to achieve this soft distortion with or without signal amplification. More overdrive can be achieved by playing harder/louder.

Overdrive is an awesome effect that plays with the dynamics of the signal. In other words, with overdrive, we get more the harder we play. This also means we can stay clean when playing softer.

• Click here to check out overdrive pedals at Sweetwater
• Click here to check out overdrive pedals at B&H Photo/Video
• Click here to check out overdrive pedals on Amazon

Distortion Pedals

What is distortion? Distortion, in terms of pedals, has to do with hard clipping of the signal, in which the waveform is more significantly deformed. Distortion yields a great deal of saturation to the signal’s harmonics and sounds more aggressive than overdrive. Distortion affects the signal across all dynamics.

As mentioned, distortion pedals are less dynamic than their overdrive counterparts. With a distortion pedal, everything quiet and loud gets distorted.

Distortion pedals give us that grittiness without having to crank our amps up to eleven.

• Click here to check out distortion pedals at Sweetwater
• Click here to check out distortion pedals at B&H Photo/Video
• Click here to check out distortion pedals on Amazon

Fuzz Pedals

What is fuzz? Fuzz is beyond hard-clipping distortion to the point where the signal becomes square-like and difficult to control. Significant odd-order harmonics are produced, and the compression is so much that any playing dynamic will be affected by the fuzz.

Fuzz is an interesting effect. It’s fundamentally a compression pedal that acts to distort a signal so much that it becomes square-like. This hard compression is similar to limiting, and the resulting output signal is similar to what a synth pedal could output.

• Click here to check out fuzz pedals at Sweetwater
• Click here to check out fuzz pedals at B&H Photo/Video
• Click here to check out fuzz pedals on Amazon

To learn more about these gain-based effects pedals, check out my article, Guitar Pedals: Boost Vs. Overdrive Vs. Distortion Vs. Fuzz.

Spectral Effects

Spectral processes refer to the frequency spectrum of audio and, sometimes, to the panoramic spectrum of an audio mix.

These effects pedals have to do with altering the frequency information of the audio and include the following:

• Equalization Pedals
• Wah Pedals
• Envelope Filter Pedals

Equalization Pedals

What is equalization? Audio equalization (EQ) is the process of altering the amplitude of certain frequencies/frequency bands in an audio signal. This includes filtering out sound below or above a certain cut-off frequency (high-pass and low-pass filtering, respectively). It also refers to shelving, notching, boosting and cutting, which we’ll get to in a moment.

By boosting and cutting various frequencies, we can effectively shape our tone to how we see fit. This means EQ will not only help us sound better alone but will also help musicians find their place within the greater context of the mix.

The types of EQ in equalization pedal circuits are typically parametric, semi-parametric or graphic. Click the links for more information on each compressor type.

• Click here to check out equalizer pedals at Sweetwater
• Click here to check out equalizer pedals at B&H Photo/Video
• Click here to check out equalizer pedals on Amazon

To learn more about EQ pedals, check out the following My New Microphone article:
• What Are EQ Pedals (Guitar/Bass) & How Do They Work?

Wah Pedals

What is Wah? Wah (or Wah-Wah) is a filtering effect that is common on guitars. Wah is achieved by sweeping one or more boosts in EQ up and down in frequency, thereby mimicking the human vowel sound of “wah”.

Wah pedals are generally built as expression pedals. Rocking the pedal back and forth will sweep the peak response of a frequency filter up and down, creating a spectral glide known as the “wah effect”.

• Click here to check out wah pedals at Sweetwater
• Click here to check out wah pedals at B&H Photo/Video
• Click here to check out wah pedals on Amazon

To learn more about wah pedals, check out the following My New Microphone article:
• What Are Wah-Wah Guitar Effects Pedals & How Do They Work?

Envelope Filter Pedals

What is envelope filtering? Envelope filtering is the filtering triggered by the envelope or transients of a signal. These filters, therefore, act according to the dynamic rise and fall of a note (or chord) from the instrument.

The sound of an envelope filter is often described as wah-like or like a duck’s quack. Various filter types (high-pass, band-pass or low-pass) can be triggered when a note is struck.

• Click here to check out envelope filter pedals at Sweetwater
• Click here to check out envelope filter pedals at B&H Photo/Video
• Click here to check out envelope filter pedals on Amazon

To learn more about envelope filter pedals, check out the following My New Microphone article:
• What Are Envelope Filter Effects Pedals & How Do They Work?

Modulation Effects

Modulation effects modify the source audio signal with another signal (generally an oscillator) and are generally used to give the sound a sense of movement. Plenty of effects fall into the modulation category, ranging from the weird-and-whacky ring modulation to the lush and wide chorus effect.

The modulation effects found in pedals include:

• Leslie/Rotary Pedals
• Chorus Pedals
• Vibrato Pedals
• Tremolo Pedals
• Phaser Pedals
• Flanger Pedals
• Ring Modulation Pedals

When choosing a modulation pedal, listen to how it moves and colours the sound. Look for speed, intensity, feedback, tap tempo, and mix controls along with stereo capability.

Leslie/Rotary Pedals

What is the Leslie/rotating effect? The Leslie effect was initially produced by the famous Leslie speaker, a unit with a rotating speaker. As the speaker rotates, three separate effects are produced in the [stationary] listener’s ears. Those effects are tremolo, the Doppler effect (vibrato) and Phasing.

So then, a Leslie/rotary pedal is essentially a 3-in-1 modulation pedal, combining the effects of a tremolo, vibrato and phaser. The result, as one would expect, is that of a Leslie speaker without a Leslie speaker!

• Click here to check out Leslie/rotary pedals at Sweetwater
• Click here to check out Leslie/rotary pedals at B&H Photo/Video
• Click here to check out Leslie/rotary pedals on Amazon

Chorus Pedals

What is chorus? Chorus is an effect that produces copies of a signal (the original signal and each of its copies has its own “voice”) and detunes each voice to produce a widening and thickening of the sound. Each voice interacts with the other voices to produce slight modulation and an overall larger-than-life sound.

Chorus pedals make the tone sound large and wide by effectively adding voices to the original sound.

• Click here to check out chorus pedals at Sweetwater
• Click here to check out chorus pedals at B&H Photo/Video
• Click here to check out chorus pedals on Amazon

To learn more about chorus pedals, check out the following My New Microphone article:
• What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work?

Vibrato Pedals

What is vibrato? Vibrato is a fast but slight up-and-down variation in pitch. Vibrato is used in signing and in instruments to add character and improve tone.

By varying the pitch, vibrato can yield everything from subtle waviness to wild pitch oscillation.

• Click here to check out vibrato pedals at Sweetwater
• Click here to check out vibrato pedals at B&H Photo/Video
• Click here to check out vibrato pedals on Amazon

To learn more about vibrato pedals, check out the following My New Microphone article:
• What Are Vibrato Guitar Effects Pedals & How Do They Work?

Tremolo Pedals

What is tremolo? Tremolo is a fast variation in amplitude. Tremolo is similar to vibrato, except that it acts on amplitude/level rather than pitch.

By varying the pitch, vibrato can yield everything from subtle waviness to deep-sea-sounding volume oscillation.

• Click here to check out tremolo pedals at Sweetwater
• Click here to check out tremolo pedals at B&H Photo/Video
• Click here to check out tremolo pedals on Amazon

To learn more about tremolo pedals, check out the following My New Microphone article:
• What Are Tremolo Guitar Effects Pedals & How Do They Work?

Phaser Pedals

What is phaser? Phaser is a modulation audio effect whereby a series of peaks and troughs are produced across the frequency spectrum of the signal’s EQ. These peaks and troughs vary over time, typically controlled by an LFO (low-frequency oscillator), to create a sweeping effect known as phaser.

Phasers sound pretty psychedelic and are a popular modulation effect.

• Click here to check out phaser pedals at Sweetwater
• Click here to check out phaser pedals at B&H Photo/Video
• Click here to check out phaser pedals on Amazon

To learn more about phaser pedals, check out the following My New Microphone article:
• What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

Flanger Pedals

What is flanger? Flanger is a modulation audio effect whereby a signal is duplicated, and the phase of one copy is continuously being shifted. This changing phase causes a sweeping comb filter effect where peaks and notches are produced in the frequency spectrum or the signal’s EQ.

Flangers tend to sound like more “natural” versions of phasers. They’re often regarded as “jet whoosh” as they make a similar effect to a plane flying overhead.

• Click here to check out flanger pedals at Sweetwater
• Click here to check out flanger pedals at B&H Photo/Video
• Click here to check out flanger pedals on Amazon

To learn more about flanger pedals, check out the following My New Microphone article:
• What Are Flanger Pedals (Guitar/Bass FX) & How Do They Work?

Ring Modulation Pedals

What is ring modulation? Ring modulation is an amplitude modulation effect where two signals (an input signal and a modulator signal) are summed together to create two brand new frequencies: the sum and difference of the input and modulator signals. The modulator wave is typically a simple wave selected by the effects unit, while the carrier signal is the audio signal at the input.

The sound of ring modulation is difficult to describe but sounds rather robotic and tinny.

• Click here to check out ring modulation pedals at Sweetwater
• Click here to check out ring modulation pedals at B&H Photo/Video
• Click here to check out ring modulation pedals on Amazon

To learn more about ring modulation pedals, check out the following My New Microphone article:
• What Are Ring Modulation Effects Pedals & How Do They Work?

Time-Based Effects

Time-based effects include all processes where some form of time manipulation occurs to the signal. The most obvious examples of time-based effects are:

• Delay Pedals
• Reverb Pedals

Delay Pedals

What is delay? Delay, in terms of pedal signal processing, is a time-based effect where an input signal is recorded for a relatively short amount of time and is played back after a set period of time after the initial recording.

Delay types found in pedals include, but are not limited to, the following:

• Tape delay: tape delay pedals emulate the sound of delay caused by mechanically shifting magnetic tape. Tape delay is often used for slapback delay.
• Analog (bucket brigade) delay: a delay circuit that utilizes bucket brigade chipsets, which degrade each passing delay.
• Digital delay: digital delay pedals convert the dry signal to digital, process the delay, and output the delays converted back as analog. This results in a very clean delay effect with little to no degradation (unless the digital pedal is designed to emulate older delays).
• Shimmer delay (aka octave delay): these pedals combine delay with pitch-shifting so that the delays are pitched differently than the dry signal.
• Reverse delay: these pedals record short sections of the signal and play it back in reverse with delay.

Delay is a versatile effect but often has a few core controls to look out for, including:

• Effect Level (Wet/Dry) Control
• Delay Time
• Feedback
• Tap Tempo

• Click here to check out delay pedals at Sweetwater
• Click here to check out delay pedals at B&H Photo/Video
• Click here to check out delay pedals on Amazon

To learn more about ring modulation pedals, check out the following My New Microphone article:
• What Are Delay Pedals (Guitar Effects) & How Do They Work?

Reverb Pedals

What is reverb? Reverberation happens when a sound wave hits a surface (or multiple surfaces) and reflects back to the listener at varying times and amplitudes. This creates a complex echo that holds information about the physical space.

Reverb types found in pedals include, but are not limited to, the following:

• Room/ Chamber/ Hall: room, chamber and hall reverb pedals emulate the reverbs of rooms, chambers and concert halls, respectively. As you can guess, the reverb sounds larger in halls than in chambers and larger in chambers than in rooms.
• Plate: plate reverb pedals emulate the sound of plate reverb, a type of reverb that relies on the vibration of a sheet of metal and a pickup that captures said vibration.
• Spring: spring reverb pedals emulate the sound of spring reverb, a type of reverb that relies on the vibration of a long metal spring within a spring reverb unit and a pickup that captures said vibration.

Reverb is a versatile effect but often has a few core controls to look out for, including:

• Mode/Type/Model
• Mix (Effect Level)
• Pre-Delay
• Decay Time
• Damping

• Click here to check out reverb pedals at Sweetwater
• Click here to check out reverb pedals at B&H Photo/Video
• Click here to check out reverb pedals on Amazon

To learn more about ring modulation pedals, check out the following My New Microphone article:
• What Are Reverb Pedals (Guitar Effects) & How Do They Work?

Utilities

• Tuner Pedals
• Expression Pedals
• Volume Pedals
• Buffer Pedals
• Switcher Pedals
• Looper Pedals
• Controller Pedals

Tuner Pedals

What is tuning? Tuning an instrument is the act of tightening or loosening the tension of the individual strings so that each string produces a defined and specific musical note.

Sure, these pedals aren’t the most flashy. In fact, they should do little to affect the tone of the signal. That being said, being in tune is paramount in sounding great, and a tuner pedal is, therefore, a worthy investment for every pedalboard!

• Click here to check out tuner pedals at Sweetwater
• Click here to check out tuner pedals at B&H Photo/Video
• Click here to check out tuner pedals on Amazon

Expression Pedals

What is expression? In the context of pedals, the term expression refers to a variable treadle-style pedal control rather than an on/off switch or a rotary knob. These pedals are similar to the expression pedals or keyboards, pianos and organs.

There are plenty of pedals on the market that have expression pedal inputs for additional functionality when combined with an expression.

• Click here to check out expression pedals at Sweetwater
• Click here to check out expression pedals at B&H Photo/Video
• Click here to check out expression pedals on Amazon

Volume Pedals

What is volume? In the context of audio signals, volume refers to the amplitude of the signal and, more specifically, to the attenuation of the signal (rather than to the amplification of the signal). Controlling volume should, by itself, leave the signal waveform unaltered except for the overall amplitude.

Volume pedals are easy to understand. Depending on how the pedal is set up, the expression pedal will allow maximum signal in either toe-down or heel-down position and no signal at the opposite position.

• Click here to check out volume pedals at Sweetwater
• Click here to check out volume pedals at B&H Photo/Video
• Click here to check out volume pedals on Amazon

Buffer Pedals

What is buffering? In the context of audio signals and pedals, buffering has to do with impedance and proper signal transfer. Long, unbalanced patch cords/cables and pedals with high output impedance can significantly degrade signal quality. A Buffer drops impedances to help preserve the signal.

Pedal signals are carried through unbalanced patch cables. Other instruments that may utilize effects pedals, including synthesizers, may also carry unbalanced signals. The pedals themselves are typically designed with unbalanced inputs and outputs.

• Click here to check out buffer pedals at Sweetwater
• Click here to check out buffer pedals at B&H Photo/Video
• Click here to check out buffer pedals on Amazon

To learn more about buffer pedals, check out the following My New Microphone article:
• Are Buffer Pedals Necessary & Where Do They Go In A Chain?

Switcher Pedals

What is switching? In the context of effects pedals, switching is the act of changing/switching the path of the audio signal. With a tap of a button, we can change the signal path to go through a different set of pedals, a different amp, or any other device(s).

Switcher pedals are very useful utility pedals. There’s a lot that can be done with them, for example:

• Redirecting the audio signal to a completely new line of pedals. This can effectively turn several pedals on/off with a single button.
• Switching between amplifiers. A switcher can have each output sent to a different amp if need be to change the tone.

• Click here to check out switcher pedals at Sweetwater
• Click here to check out switcher pedals at B&H Photo/Video
• Click here to check out switcher pedals on Amazon

To learn more about switch pedals, check out my article What Is A Guitar Pedal Switcher & How Do Switchers Work?

Looper Pedals

What is looping? Looping is the process of recording a period of audio and having it repeat. Once a loop is established, it is common to stack other audio recordings on top of the loop (or take other audio recordings out of the loop).

Looper pedals are awesome units to have in a rig. They range from simple to complex with a variety of functions. We will often be capable of adding additional loops on top of an original loop and be able to remove loops as we see fit.

• Click here to check out looper pedals at Sweetwater
• Click here to check out looper pedals at B&H Photo/Video
• Click here to check out looper pedals on Amazon

To learn more about looper pedals, check out the following My New Microphone article:
• What Are Looper Pedals (Guitar/Bass FX) & How Do They Work?

Controller Pedals

What are controller pedals? Controller pedals will effectively control either an amplifier or software on a computer. These pedals do not necessarily have effect circuits of their own but rather act to control signal flow in other pieces of the rig.

There are plenty of controller pedals that simply switch between an amp’s clean and distortion channels. In a way, these controller pedals are also line-switcher pedals.

• Click here to check out controller pedals at Sweetwater
• Click here to check out controller pedals at B&H Photo/Video
• Click here to check out controller pedals on Amazon

Synth Pedals

What is audio synthesis? Audio synthesis is loosely defined as the audio signals generated by electronic musical instruments called synthesizers. Synth pedals turn instrument audio signals into “synthesizer-like” sound waves.

The vast majority of synth pedals do not actually alter the waveform of the instrument signal itself, as is the case with pretty much all other pedals. Rather, a synth pedal will typically detect the pitch of the instrument's signal and use that pitch to tune and engage its built-in synthesizer oscillator(s).

So, a synth pedal, generally speaking, will use the instrument signal only as a control signal rather than actually affecting the signal and tone itself.

• Click here to check out synth pedals at Sweetwater
• Click here to check out synth pedals at B&H Photo/Video
• Click here to check out synth pedals on Amazon

To learn more about synth pedals, check out the following My New Microphone article:
• What Are Synth Pedals (Guitar/Bass FX) & How Do They Work?

Miscellaneous Effects

Miscellaneous effects include all the odd effects that don't fit into any of the categories above. Most pedals on the market will belong to at least one of the aforementioned categories, but there will be some that do not.

Back to the Table Of Contents.

Mono Vs. Stereo Effect Pedals

Pedals have inputs and outputs, which can either be mono or stereo.

Mono has a single channel of audio, while stereo has a left and right channel of audio.

Though we naturally hear in stereo, many instruments are mono.

Choosing a pedal with stereo outputs allows us to record or otherwise playback the sound in two channels, which is beneficial for a more realistic mix.

Stereo outputs are typically reserved for modulation and time-based effects, which act to widen or otherwise fill the sound field.

Stereo pedals will give us the option of going stereo but typically perform just as well in mono (typically by connecting to the left output channel only).

So, if you're considering recording, sending to a stereo PA system, or even connecting to two amplifiers simultaneously, a stereo pedal will give you the option.

• Click here to check out stereo pedals at Sweetwater
• Click here to check out stereo pedals at B&H Photo/Video
• Click here to check out stereo pedals on Amazon

Back to the Table Of Contents.

True Bypass Vs. Buffered Bypass Pedals

Individual single-effect pedals are either true bypass or buffered bypass. Knowing the difference between the two and understanding how they interact in a pedalboard setup will help you make more informed decisions about your pedal purchases.

True bypass is a switching circuit that will route the guitar signal directly from the input to the output when the pedal is turned off. A pedal with true bypass will effectively act as an extension of the guitar cable when turned off and have little to no effect on signal tone/degradation.

Note that longer cable lengths are subjected to “tone suck” thanks to cumulative capacitance. High-end frequencies are effectively filtered out, and the tone suffers.

Buffered bypass keeps part of the circuit in the signal path regardless of whether the pedal's main circuit is active. A pedal with buffered bypass, then, will maintain consistent output impedance and keep a signal more level in signal strength and timbre throughout the system.

By keeping part of the circuitry in the signal path even when the pedal is off, the buffered bypass pedal will colour the audio signal in one way or another.

So then, which should you buy? Let's look at the pros and cons lists for each pedal style to help you decide:

Pros Of True Bypass

True bypass removes the pedal circuit completely from the signal path when off. This means that the pedal will have no effect on the sound of the audio signal when it's turned off.

Cons Of True Bypass

By removing the pedal from the signal chain when turned off, true bypass pedals effectively elongate the signal wire (audio cable), which can cause tone suck in longer runs. We typically begin having issues with unbalanced cables over 25 feet long.

Since true bypass immediately disconnects the pedal's circuit from the signal chain, turning these pedals on/off can result in pops and clicks. Furthermore, turning these pedals off may cause hard stops (no tail) in time-based effects such as delay and reverb.

Finally, true bypass pedals are often more expensive than their buffered bypass counterparts.

• Click here to check out true bypass pedals at Sweetwater
• Click here to check out true bypass pedals at B&H Photo/Video
• Click here to check out true bypass pedals on Amazon

Pros Of Buffered Bypass

Like proper buffer pedals, buffered bypass pedals offer impedance and capacitance altering. This effectively buffers the signal, bringing its signal strength, impedance and capacitance to appropriate levels even when turned off. This allows for longer cable runs since each buffered bypass pedal “restarts” the cable length.

Unlike true bypass pedals, buffered bypass pedals do not produce the pops and clicks when turned off/on and do not necessarily hard-stop their effects when disengaged.

Buffered bypass pedals often typically cost less, all else being equal.

Cons Of Buffered Bypass

Buffered bypass pedals colour the tone whether they're engaged or not, which can lead to unwanted results when there are too many pedals on the board.

• Click here to check out buffered bypass pedals at Sweetwater
• Click here to check out buffered bypass pedals at B&H Photo/Video
• Click here to check out buffered bypass pedals on Amazon

Related My New Microphone article:
• What Does ‘True Bypass’ Mean In A Guitar Pedal?

In my opinion, a good mix of true and buffered bypass pedals is the way to go when designing a pedalboard layout.

Back to the Table Of Contents.

Planning Out The Pedalboard

When buying a new effect pedal, it's worth considering how it will integrate into the larger pedalboard setup.

Understanding how the pedal will interact with the others and where the pedal should go ahead of time is useful information to have when making a decision.

Additionally, if you already have pedals on your board, perhaps it's best to purchase an effect you don't already have. For example, a third fuzz pedal may not be appropriate when you don't have a proper reverb.

Though not the most critical aspect of a new pedal purchase, it's worth pondering the plan of the pedalboard and how the new pedal(s) will be incorporated.

Related My New Microphone article:
• Ultimate Guide To Setting Up A Guitar Effects Pedalboard
• How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide)
• How Many Guitar Effect Pedals Is Too Many?

Back to the Table Of Contents.

Know The Additional Costs Of Effect Pedal Accessories

• Power Supplies & Power Accessories
• Pedalboards & Accessories
• Patch Cables

Power Supplies & Power Accessories

Pedals require power to function. Power supplies include batteries, dedicated power blocks and their power cables, and the power cable adapters for the pedals.

Most pedals can run on 9V batteries, though some pedals use other battery types.

Generally speaking, though, it's best to power the pedals directly via a dedicated pedal power block and the appropriate power adapter cables.

• Click here to check out pedal power supplies at Sweetwater
• Click here to check out pedal power supplies at B&H Photo/Video
• Click here to check out pedal power supplies on Amazon

Pedalboards & Accessories

If you're using multiple pedals, you'll benefit greatly from a pedalboard. Opting for a pedalboard with good adhesives and a proper carrying case/bag is recommended for the performance and longevity of the entire setup.

• Click here to check out pedalboards at Sweetwater
• Click here to check out pedalboards at B&H Photo/Video
• Click here to check out pedalboards on Amazon

Related My New Microphone article:
• Top 11 Best Pedalboard Brands On The Market

Patch Cables

Of course, we need patch cables to connect the pedals together. These cables are typically short 1/4″ TS cables, but some pedals have the options for MIDI and other connections as well.

• Click here to check out pedal patch cables at Sweetwater
• Click here to check out pedal patch cables at B&H Photo/Video
• Click here to check out pedal patch cables on Amazon

Related My New Microphone articles:
• Top 11 Best Guitar/Bass Patch Cable Brands In The World
• How Do Patch Cables Carry Audio? (Guitar, Bass, Synth, Etc.)

Back to the Table Of Contents.

The post The Ultimate Effects Pedal/Stompbox Buyer’s Guide first appeared on My New Microphone and is written by Arthur Fox.

For guitarists and bassists enthusiastic about hardware effects, the stompbox/pedal collection can get rather large. Choosing the right effects pedals and the order of such stompboxes is one thing, but keeping them all organized and easily transportable is another ordeal. This is where pedalboards come into play.

Though there are plenty of multi-effects and all-in-one modeling pedals out there, many musicians choose the more modular route of accumulating individual pedals. A proper pedalboard, having the appropriate size, durability, and, in some cases, power is often a requirement for easy transportation, set up and overall performance.

It's perfectly reasonable, then, to see so many brands offering pedalboards on the market. Among all the options, I've compiled what I believe to be the top 11.

Though obviously subjective and prone to biases, I’ve done my best to list out these brands based on the following metrics (in no particular order):

• Company reputation
• Variety of pedalboard options
• Performance of the pedalboard
• Accessibility of the pedalboard (how easy are they to find?)
• The company must currently be in operation

With all that being said, let’s list out the brands.

The Top 11 Best Pedalboard Brands Are:

1. Pedaltrain
2. Temple Audio
3. Gator
4. Friedman
5. Voodoo Lab
6. Ruach
7. Ultimate Support
8. RockBoard
9. Boss
10. Emerson Custom
11. Mono

Let’s get into each of these brands in greater detail and explain why they belong in the top 11 best pedalboard brands. I’ll share their country of origin, a bit of history, an example of a notable set of strings, and a link to their official website.

Click here to return to My New Microphone’s articles on musical equipment brands/manufacturers.

Pedaltrain

John Chandler founded Pedaltrain in 1999 in Nashville, Tennessee, where it still holds its headquarters. The idea for the company popped into his head after being on the road for many years as a guitar tech with famous acts.

What was revolutionary about Pedaltrain was the hollow aluminum frame with the inner “pocket” to install your power supply underneath an inclined design.

This allowed players to save space on the top, maximizing surface footprint to add more pedals.

It all started as one man’s vision and turned into a worldwide phenomenon that is easily spotted in the biggest stages around the world. Pedaltrain is a synonym with the highest-quality craftsmanship and reliability. You can learn more about it in this interview.

Notable pedalboard: Terra TCW 42″ x 14.5″

This is Pedaltrain’s biggest model. Although it looks like a spaceship, the frame is only 6.1 lbs (less than 3kg). This version of the Terra comes with a tour-proof wheeled tour case, but it is also possible to get it in its soft-case version for domestic gigs.

The Terra also comes with an assortment of zip ties to attach the pedals to the aircraft-grade aluminum frame. The new, modified rail frame can accommodate newer, smaller pedals, ensuring optimum adhesion and support.

If you want the best for your pedal collection, this might be it.

Temple Audio

Temple Audio is the creation of Ryan Dyck. It all started in 2009 when he was requested to build a custom pedalboard for an artist while abroad and with limited resources. Need took him to use unconventional materials, and the result was nothing short of astonishing.

This was the seed that, with hard work and relentless dedication, Ryan turned into a world-class company shipping pedalboards around the world. The leverage and knowledge that the road gave him opened the door to ultimate creativity in the service of music.

Temple Audio employs revolutionary thinking to solve modern-day musician problems; you must check them out before buying any other brand.

Notable pedalboard: TRIO 28 Templeboard Kit

This lightweight aluminum board requires no Velcro to guarantee the pedals will be steady during the gig or transit situations. Also, it is the perfect DIY canvas to design your dream pedalboard since there are endless possible combinations for its surface.

Among the revolutionary add-ons found in this pedalboard, you’ll find a 4-way jack patch mini-module to plug everything and achieve mono or stereo configurations. Also, a switching IEC micro module that works wonders interfacing with any power supply in the market.

Finally, it comes with a road-ready soft case to carry it anywhere.

Temple Audio came up with a solution to everyday problems; it is high time you give it a try.

Gator

Gator Cases was born in the year 2000 as a father and daughter endeavour in Tampa, Florida. After a successful first NAMM appearance that year, the company grew its line to over 1,000 solutions for all audio and video-related professionals.

After a meteoric rise, the steady volume of sales and the purchase of other bag and case companies took Gator to a new facility of over 180,000 square feet where all production is centralized.

Nowadays, besides being one of the biggest OEM case manufacturers on the planet, Gator's lines of bags and cases can be found in most music stores around the world.

If you want to work with the best in the business, you have to give Gator a chance.

Notable pedalboard: G-Tour Pedalboard-XLGW

This pedalboard with a wheeled flight case can fit up to 25 pedals inside a 34×17” removable surface. The case's interior is fitted with EVA foam and features industrial-grade Dual Lock Hook 3M locks and a loop fastener for a secure pedal installation.

Also, the spring-loaded rubber grip handles in red offer uncanny lifting and carrying aid while staying out of the way the rest of the time. Finally, the protective ball corners cover all vulnerable points the case might have.

Rolling with the best is rolling with a Gator G-Tour pedalboard. Here’s a video to see it up close.

Friedman

Dave Friedman is the man responsible for some of the most sought-after tones in the history of music. He has been an active amplifier builder and modifier for figures the size of Eddie Van Halen and Jerry Cantrel (Alice in Chains), and countless others.

The company started in sunny California after 25 years of amplifier modding wizardry with one head, the BE-100 that can be found fueling the Foo Fighters or Joe Bonamassa’s live performances.

Soon, Friedman’s notoriety grew so much that it branched toward guitars, effects pedals, and pedalboards.

Following the same motto of excellence that took the company to the pinnacle of amplification, all Friedman-stamped products are road-tested and possess three decades of know-how applied to every bolt.

Dave Friedman has been building pedalboards for rockstars for almost 30 years; you owe them a try.

Notable pedalboard: Tour Pro 1530 15″x30″

This pedalboard by Friedman doesn’t look like any other you might have seen so far. To begin with, it is a hybrid design with a slanted top tier and a flat bottom tier. This allows for easy access to the bottom and upper row without touching any dials with your heels.

Furthermore, the bottom tier features two risers to accommodate expression or wah pedals that can be moved horizontally so left-handed players can use the foot they feel the most comfortable with.

Finally, the bag is among the best you can find in the market.

This revolutionary approach to pedalboards could be the answer to your everyday pedal problems; see it in action in this video.

Voodoo Lab

From day one, Voodoo Lab was a company conceived from musicians to musicians that built a reputation for making sturdy, road-ready, and reliable products.

Their famous pedal series, capable of some of the purest, richest analog tones in the market that could also survive the hardship of nineties rage, put the company on the map for musicians worldwide.

Nowadays, after more than three decades of restless innovation and seeing countless stages all over the planet, Voodoo Lab owns the know-how to make some of the best pedalboards you can stomp on. Try them before making any decisions.

Notable pedalboard: Dingbat 22″ x 13.5″

Entirely made out of superior 6061-T6 aircraft-grade aluminum in Sonoma, California, this patent-pending design is perfect for laying out pedals and tucking cables out of sight.

Moreover, the road-ready gig bag is among the sturdiest in the market, and the platform it contains can fit 6 to 10 effects pedals. The pedalboard also comes with zip ties, loop tape, and 4-way tie mounts to make sure the cabling underneath is secure and tight.

Finally, up to two different power supplies can fit underneath your pedals for optimum performance.

Ruach

Stephen Henderson started his company in 2011 when he was only 16 years old. The spark that lit that flame came from a Cajon at a friend’s house during a jam session. He couldn't afford one, so he built himself the first product of what would become his dream company.

After a ton of hard work and, with the help of word of mouth, demand grew so dramatically that he had to hire a team and branch out to manufacture other musical instruments and accessories. Thus, Ruach pedalboards were born.

Because of Stephen’s drive, passion for innovation, and wizardry with wood, Ruach pedalboards are sturdy, lightweight, and feature a plethora of benefits that granted a growing number of fans.

From dream to reality, from Ireland to your feet, you have to check Ruach pedalboards out.

Notable pedalboard: Infinity Series 4

Made of a mixture of aluminum bars and wooden profiles, this Ruach Infinity Series pedalboard not only works perfectly for life on the stage but looks amazing, too.

To begin with, it comes complete with all the Velcro you need to install at least 18 Boss-type pedals comfortably on its surface. Secondly, it features a road-ready gig bag. Finally, the entire structure weighs only 2 kilograms. Plus, it can be expanded if your collection grows.

Although this company is new to the market, it managed to create a product that can compete with the best, most experienced brands out there.

Ultimate Support

In their own words, the company strives to be in a constant “patent pending” state; in other words, continually innovating. Although they have been in the market making stands for the Oscars and the Grammys for over 40 years, they have no intention of slowing down.

The heart and soul of the project is musician, entrepreneur, and inventor Darrell Schoenig, who started making speaker stands as far back as 1977.

After more than four decades of relentless dedication to innovating, the quality of Ultimate Support’s pedalboards is second to none. You can certainly trust the trajectory that took a man’s dream all the way to the top of the crop to put your pedals on.

Notable pedalboard: UPD-2416-B

This is the biggest size available for the new UPD series of pedalboards by Ultimate Support. It is entirely made of lightweight aluminum and features a road-ready gig bag with a big pocket to put away cables safely.

On the bottom of the pedalboard, you can find a tray to which you attach your power supply and then bolt it to the structure securely. You won’t use any footprint to power your pedals or worry about it falling off ever again.

This no-frills approach to pedalboard building separates Ultimate Support’s UPD series from many of the rest of the best pedalboards in the market. Try them out before you make any decisions.

You can learn more about the series in this video.

RockBoard

RockBoard is a division of Warwick, a German company founded in 1982 by Hans-Peter Wilfer, which is famous for building basses played by legends like Adam Clayton (U2), Robert Trujillo (Metallica), and many others.

Working with legends of that size gave the company a privileged peek into the demanding size of stardom. Thus, they learned how to make products that could perform even at the most challenging stages in the world.

Their pedalboard line is no exception to their commitment to excellence and could bring your rig to the next level.

Notable pedalboard: Cinque 5.4

This is one of the biggest models available in the market and can fit up to 30 pedals, depending on their size. It comes complete in three versions: with a soft bag, an ABS case, or a flight case.

The RockBoard Cinque 5.4 is entirely made out of a single cold-rolled aluminum sheet and features U-shaped support braces to add rigidity. Also, its surface is angled by ten degrees and features no wielding under the robust black powder coating.

Finally, it comes complete with a self-adhesive hook, loop tape, and cable ties.

Whichever is the size of the gig you’re playing, you can’t go wrong with a RockBoard Cinque at your feet.

Boss

If you have ever owned any pedal, you might know that Boss is the benchmark by which all others are measured. Moreover, most pedalboards use the quintessential “Boss pedal size” to manufacture their platforms.

As a part of the Roland Corporation, this Japanese company was founded in 1973. It was in 1976 that it released to the world the utterly famous CE-1 Chorus Ensemble pedal, which not only shaped the sound of a decade but also defined what an effects pedal should be.

Furthermore, it can still be found in the pedalboard of legends like John Frusciante.

Thanks to its status as a go-to brand for effects lovers worldwide for decades, Boss gained the necessary knowledge to design and manufacture some of the best accessories to go with them, including pedalboards.

Notable pedalboard: BCB-1000 Deluxe

With the size of a carry-on suitcase, complete with a handle and a set of wheels, this pedalboard by Boss is one of the most comfortable in the market for musicians on the go.

The outer structure is rugged and can take the abuse of the road, including being thrown around by airport staff.

Once laid on solid ground, though, the interior aluminum frame can be detached, and it features a built-in junction box so you can plug straight into the pedalboard and be ready in less than a minute.

This pedalboard features the quality and dependability you would expect from a company the size of Boss and then some. If you are on the road a lot, this could be the pedalboard you were looking for. You can check the entire line in this video.

Emerson Custom

For those in search of boutique-grade craftsmanship and attention to detail, this family-owned business created in Bixby, Oklahoma, in 2009 might be the perfect match.

They started making hand-wired pedals and guitar components such as pickups and pre-wired kits. Because of the critical acclaim and a meteoric rise in demand, they also branched out to the pedalboard market.

Nowadays, the family still manufactures products in-house and ships them around the world to a growing network of over 100 dealers.

No other company in this list features this level of attention to detail and craftsmanship. If that is your cup of tea, you need to check Emerson Custom before buying your next pedalboard.

Notable pedalboard: Megaboard 32″ x 18″

This huge board is made of a lightweight aluminum frame with dual cherry wood end caps. The specially designed frame includes multiple holes and spaces to Velcro your pedals down with the included yard of Dual Lock fastening material and arranges your cables in a tidy, almost invisible way.

Underneath the aluminum frame, you’ll also find space to mount your power supply without taking up any space on the surface. This is a 100% road-ready companion that will withstand your hardest gigs and remain firm at your feet.

Mono

Names like The Red Hot Chili Peppers, Black Sabbath, The Rolling Stones, and Death Cab For Cutie are just some of the many in Mono Creators’ clients’ list.

Indeed, this San Francisco-based bag brand founded by Daniel Kushner in 2007 gained uncanny notoriety in a very short time for being the best-designed, most innovative bags in the market.

Moreover, they won the Industrial Designer Society of America Award (IDSA). Although BandLab acquired the company on September 8th, 2016, Dave is still its CEO.

The fine line dividing design, comfort, and performance doesn’t seem to exist for this brand, and their pedalboards can be seen in the hands of the most famous musicians in the world. If you truly want to experience this revolution, it is high time you give MONO a try.

Notable pedalboard: Pedalboard Large 32″ x 16″

Cut from a single sheet of anodized aluminum and accompanied by a military-grade luggage bag, this gig bag is road-ready, lightweight, and easy to equip.

To begin with, the single sheet of aluminum from which the entire pedalboard is crafted allows a no-wield structure that will withstand any and all scenarios.

Also, the bag comes with plastic-reinforced hybrid shells that allow for a minimum weight and maximum protection. Speaking of which, the plush top panels protect knobs and switches like no other brand.

If you are ready to take on the world with your music, this MONO pedalboard can be the best vessel to get to the top.

The post Top 11 Best Pedalboard Brands On The Market first appeared on My New Microphone and is written by Arthur Fox.

Modulation effects (and modulation in general) are powerful tools when it comes to processing audio. There are plenty of distinct effects that fall into the great category of modulation that we should understand and have at our disposal when mixing audio or sculpting the perfect tone in our instrument.

What are audio modulation effects? Audio modulation effects manipulate the input audio over time via the control of a carrier signal. The input audio is referred to as the modulator signal, which technically controls the carrier signal, which is generally produced via an oscillator generator or signal detector.

This quick definition is broad at best. In this article, we'll get into the details of how modulation works. We'll also dive into the different audio effects that utilize modulation, from flangers and phasers to ring modulators and vocoders) to develop our understanding of this awesome effect category.

Table Of Contents

• What Is Modulation?
• The Modulator
• The Carrier
  • Oscillator
  • Envelope
  • Secondary Input Signal
  • Expression Controller
  • Sequencer
• Standard Modulation Effects
  • Tremolo
  • Vibrato
  • Chorus
  • Flanger
  • Phaser
  • Auto-Pan
  • Ring Modulation
• Other Effects That Use Modulation
  • Vocoder
  • Wah-Wah
  • Auto-Wah/Envelope Filter
  • Octavers
• Other Uses Of Modulation In Audio

Jump ahead to the section titled Standard Modulation Effects to skip the discussion on modulation, modulator signals and carrier signals and get straight to the effects.

What Is Modulation?

What is modulation? Modulation, in regards to audio, is not an effect by itself. Rather, it's a process in which one signal (the modulator) controls one or more parameters of another signal (the carrier). Modulation is used by several audio effects known collectively as “modulation effects”.

Some “modulation effects” will often show up in other categories (instruments, spectral effects, etc.) but are technically modulation effects (in addition to being parts of other categories). In this article, we'll touch on them all.

So, with a modulation effect, we have a modulator signal that will modulate a carrier signal. When it comes to audio effects, the modulator will nearly always be the input audio signal. The carrier, then, will be one of the following:

• Oscillator generated by the effect
• Input-generated signal (envelope or octave)
• Separate input signal
• Expression controller
• Sequencer

For the typical modulation effects (chorus, flanger, phaser, tremolo and vibrato), the carrier is an LFO (low-frequency oscillator). However, to truly understand modulation, we will look at all the other carrier types.

Before we get into our discussion on the modulator and carrier signals, I'll reiterate the term modulation: Modulation simply means that one signal is being controlled by another signal. The factors that can be controlled are plentiful and different effects will have different modulated parameters.

The Modulator

What is the modulator signal? The modulator signal is the signal in a modulation effect that will modulate (manipulate one or more parameters) the carrier signal).

The modulator signal is simply the input signal. This can be any audio signal that is processed by the modulation effect.

Oftentimes the modulator will be an instrument signal through an effects unit or vocal. Of course, it can be any audio signal that the modulation effect can effectively process.

Note that modulation effects can be designed to accept instrument, mic and/or line level signals. They can also be software effects that process audio within a computer or digital audio workstation. When we discuss the types of modulation effects, I'll be sure to offer examples of the various effect unit formats.

The Carrier

What is the carrier signal? The carrier signal is the signal in a modulation effect that will be modulated (have one or more of its parameters manipulated) by the modulator signal.

As we've discussed, the carrier is the signal that will be modulated and is generally either created by or detected by the effects unit itself.

The terminology can be confusing here, as we generally imagine a modulation effect as “modulating” the signal we input into it. However, technically speaking, the input signal is the “modulator”.

Of course, this is only the terminology. When actually using these effects, it's more about the sound than the names. That being said, it's important that, for this article, we get the housekeeping out of the way.

Okay, so we have a few different types of carrier signals to discuss:

• Oscillator
• Envelope
• Secondary Input Signal
• Expression Controller
• Sequencer

Oscillator

What is an oscillator? An oscillator is a periodic, oscillating signal that moves between a minimum and maximum value. Oscillators often have a sine or square waveform but can have any repeating waveform. Oscillators will also have a fundamental frequency and, potentially, a harmonic profile.

Let's have a look at a graphic representation of the 4 most basic oscillator waveforms (notice that each waveform repeats twice in the following graphic and that the waveforms are named after their appearance):

• Sine wave: green
• Square wave: blue
• Triangle wave: red
• Sawtooth wave: orange

In the majority of the modulation effects that utilize oscillators, the carrier will be a sine wave, though that's not always the case. Some units will offer alternate waveforms. For the rest of the article, let's assume that the oscillator is a sine wave unless otherwise noted.

An oscillator is generally defined by its amplitude (whether that's in volts or decibels of some sort) and its frequency (cycles/second). Have a look at the following photo to get an idea of the basics of a sine wave:

We can see that a modulation effect can modulate a sound parameter up and down in a repeated pattern with an oscillator. This parameter can be:

• Amplitude of the input signal (tremolo and ring modulation)
• Delay time of a delay circuit (vibrato, chorus and flanger)
• Corner frequency of cascading all-pass filters (phaser)
• Pan position of the signal (auto-pan)

We'll get to these effects shortly (click the links to jump ahead to any of the mentioned effects.

The oscillator(s) in these effects units will typically be produced by the effects units themselves. In some cases, the oscillator may be inputted from another source if that's what is required.

The oscillator frequency (the rate at which a full period is completed) is also important when it comes to oscillator carrier signals. Frequency is measured in Hertz (Hz), which means cycles or periods per second. Note that the audible range of human hearing is in the frequency range of 20 Hz to 20,000 Hz.

When it comes to modulation effects, low-frequency oscillators (LFOs) are the most common carrier oscillators. LFOs are loosely defined as oscillators with frequencies below the audible threshold of 20 Hz, though they are often well below 20 Hz.

LFOs are used in tremolo, vibrato, chorus, flanger, phaser and auto-pan modulation effects.

In the audible frequency range, oscillators are used as audio sources in synthesizers but can also be used as carrier signals in the ring modulation effect. Oscillators within this range are also used in frequency modulation (FM) synthesis to modulate other oscillators, some of which may be outputted as audio.

Though not useful for audible modulation effects per se, it's important to mention carrier wave oscillators with very high or ultra-high frequencies. These carriers are used in AM (amplitude modulation) radio transmission, which is in the range of 550 to 1720 kHz, FM (frequency-modulation) radio transmission, which is in the range of 88 to 108 MHz, and other processes.

Envelope

What is an envelope? In regards to audio, an envelope is a description of how a sound or audio signal changes over time. Envelopes often refer to the amplitude of a signal/sound. Still, they may also refer to any other parameter that either naturally changes over time or is modulated by an envelope generator to change over time.

The “carrier” may be an envelope. This can certainly be the case with synthesizers, samplers and other electronic instruments that often rely on envelope generators to modulate various parameters of the synth's signal(s).

Envelope generators typically have four stages which also apply to natural envelopes. They are the ADSR stages (attack, decay, sustain, release):

• Attack: the time taken for the initial increase from zero to the peak of the envelope.
• Decay: the time taken for the subsequent decrease from the peak to the sustain level of the envelope.
• Sustain: the level during the main sequence while the envelope is engaged (generally as the key of the synthesizer is pressed).
• Release: the time taken for the level to decay from the sustain level to zero after the envelope is disengaged (the key is released).

Though envelope generators are used in synths to modulate all sorts of parameters, they're not overly common in modulation effects themselves. That being said, it's good to know about ADSR to grasp the idea of an envelope better.

An envelope can also be used in a modulation-type effect unit. This is the case with the auto-wah/envelope filter effect, which effectively detects the envelope of the input signal and uses that envelope information/signal to control a filter of some sort.

The input signal's amplitude can be detected and analyzed to produce an envelope that can then be used to control/modulate another parameter. As mentioned, the envelope filter effect uses this info to modulate a filter.

Secondary Input Signal

Some modulation-style units can take in two different signals and use one to modulate the other. This is the case when an oscillator generator is plugged into a unit. It's also the case with the vocoder. Perhaps a vocoder isn't technically a “modulation effect,” but rather it's its own instrument. That being said, it's an awesome use of modulation in audio and source. More on vocoders later.

The point here is that any signal can modulate any other signal. Of course, some signals make for better modulators, and others make for better carriers. It's also true that not all parameters can be modulated to achieve a practical effect.

That being said, carrier waves could be more than just oscillators or envelopes. They could be their very own audio signals.

Expression Controller

What is an expression controller? In the context of audio signals, an expression controller is any control that can modulate the parameters of an effect or instrument.

This is where things get tricky. Is a volume fader a modulation effect? What about a gain knob? Both these controls can expressively alter the amplitude of a signal, so where do we draw the line?

Well, the truth is that expression controllers, whether they're expression pedals, modulation wheels, faders or otherwise, can certainly be linked to modulate certain parameters, but that doesn't necessarily make any particular link a “modulation effect”.

More on this in the upcoming section Standard Modulation Effects.

One expression effect worth mentioning is wah-wah, which uses an expression controller (typically an expression pedal) to achieve spectral glide in a signal's frequency response, thereby modulating the EQ/filters of the signal to cause a distinctive “wah-wah” sound. Some people, particularly in the world of guitar, would consider wah-wah, then, to be a
modulation effect”.

I'll discuss modulation controllers in more detail at the end of this article.

Standard Modulation Effects

So far, we've discovered what modulation is and the various ways it shows up in audio. We know by now that not all modulation is to be considered a “modulation effect”.

There are countless ways in which modulation can be used practically, but only a few dedicated modulation effects stand out as distinct audio effects. Most modulation, whether in a synthesizer, sampler, digital audio workstation or otherwise, is awesome but not necessarily an “effect”.

The main distinction, I suppose, between general modulation and standard modulation effect is that the effect will have its own carrier signal and will act upon an audio signal at the input.

By that definition, all standard modulation effects will have the oscillator-type carrier signal. This is the case if you even look at your DAW's modulation effects category; browse “modulation effects units” at your local or online shop (hardware and software), or read any other articles on the subject.

So then, the definitive list of modulation effects would be:

• Tremolo
• Vibrato
• Chorus
• Flanger
• Phaser
• Auto-Pan
• Ring Modulation

I'll discuss the other common effects that utilize modulation in the section titled Other Effects That Use Modulation. I'll also touch on other uses of modulation in audio in the section Other Uses Of Modulation In Audio. However, before that, let's get to the main part of this article and discuss the various modulation effects.

Tremolo

What is tremolo? Tremolo is defined by a fast variation in amplitude. Tremolo is similar to vibrato, except that it acts on amplitude/level rather than pitch.

Why is tremolo a modulation effect? Tremolo is a modulation effect because the amplitude of the input signal is modulated via an LFO. Tremolo is a type of amplitude modulation where the carrier signal is a low-frequency oscillator.

I've decided to start with tremolo since it's perhaps the easiest to understand and visualize (at least for me, it is). If we can grasp the tremolo effect first, we'll have an easier time understanding the other modulation effect types.

So, as I've mentioned, tremolo is amplitude modulation at the rate of an LFO. Because of this relatively slow modulation, we are able to hear a distinct modulation in the signal's amplitude. The volume/amplitude of the signal can be perceived as rising and falling according to the LFO modulation.

The tremolo effects will often use an LFO with a frequency between 2 and 12 Hz. The LFO is often a sine wave but can also be other waveforms as well, including triangle and square.

The speed/rate control of a tremolo pedal affects the frequency of the LFO. The amplitude of the LFO will control the amount/depth of the tremolo's attenuation of the guitar/bass/instrument audio signal.

Tremolo can be visualized in the following image, where:

• Top: input signal “modulator”
• Middle: LFO “carrier”
• Bottom: Output

In the image above, we can clearly see the effect of amplitude modulation and modulation more generally. The middle waveform controls/modulates the amplitude of the first waveform to produce the third waveform.

Common tremolo effect controls include:

• Depth/Intensity: adjusts the amount of amplitude variation the tremolo effect will cause.
• Rate/Speed: adjusts the rate of the tremolo effect by changing. the frequency of the LFO.
• Shape: alters the waveform of the LFO.
• Tap Tempo: allows users to tap in a tempo and the LFO frequency to the tempo.
• Ratio: adjusts the rate according to the tapped tempo by way of a rhythmic selection (quarter notes, quarter note triplets, dotted eighth notes, etc.).
• Level: controls the overall output level of the effect unit.

Let's have a look at a few examples of tremolo effects units:

• Notable 500 Series tremolo unit: JHS Kodiak 500
• Notable 19″ rack mount tremolo unit: Rocktron Big Surf
• Notable tremolo effect pedal: Voodoo Lab Tremolo
• Notable tremolo plugin: Soundtoys Tremolator

The tremolo effect can be achieved in other ways besides electrical modulation. Let's look at a few examples:

• Naturally modulating the amplitude of your voice.
• Tremolo picking on stringed instruments (rapid reiteration).
• Riding a volume control up and down.

Related articles:
• What Are Tremolo Guitar Effects Pedals & How Do They Work?
• Top 11 Best Tremolo Pedals For Guitar & Bass
• Top 11 Best Tremolo Modulation Plugins For Your DAW

A note for guitarists: The “tremolo arm” (aka whammy bar) on a guitar is actually designed to provide an effect similar to vibrato (called a glissando, since it's smooth and is not linked to time), not tremolo.

Vibrato

What is vibrato? Vibrato is defined as a fast but slight up-and-down variation in pitch. Vibrato is used in signing and in instruments to add character and improve tone.

Why is vibrato a modulation effect? Vibrato is a pitch modulation effect because the delay time parameter of the delay line is modulated via an LFO. As the delay time is modulated, the audio is time-compressed and time-expanded in real-time, producing a variation in perceived pitch.

Vibrato effects units utilize modulation in an attempt to mimic the natural vibrato of vocals and stringed instruments.

This modulation effect modulates the pitch of the signal.

Vibrato, like chorus and flanger (we'll get to those shortly), is technically a modulated delay effect. These effects work by sending the input signal through a delay line and modulating the delay time with an LFO.

With vibrato, the output signal is only from the delay line. A basic vibrato signal path would look like this:

How does modulating the delay time affect pitch? As the delay time is shortened, the waveform is slightly compressed, causing an increase in pitch/frequency. Conversely, as the delay time is lengthened, the waveform is slightly stretched, causing a decrease in pitch/frequency.

The same thing happens with the time-compression and time-expansion of samples. Stretching an audio sample out will lower its pitch, while compressing the time of an audio sample will increase its pitch.

Because an LFO modulates the delay time, we can hear the distinct pitch-altering effect of vibrato. The frequency of the LFO determines the rate of the vibrato effect, and the amplitude of the LFO determines the amount of pitch-shift that will take place.

To reduce any audible lag, the delay time is kept as close to 0 milliseconds as possible and is modulated from there.

Common vibrato effect controls include:

• Depth: controls the amount of pitch variation by adjusting the amplitude of the LFO.
• Speed/Rate: controls the speed of the vibrato effect by adjusting the frequency of the LFO.
• Rise Time/Ramp: controls the initial onset of the vibrato effect once the effect is engaged by adjusting the attack of the LFO envelope.

Let's have a look at a few examples of vibrato effects units:

• Notable 500 Series vibrato unit: JHS Emperor 500
• Notable 19″ rack mount vibrato unit: Matchless TV-1
• Notable vibrato effect pedal: Boss VB-2W Waza Craft
• Notable vibrato plugin: MeldaProduction MVibratoMB

The tremolo effect can be achieved in other ways besides electrical modulation. Let's look at a few examples:

• Naturally modulating the pitch of your voice.
• Bending on stringed instruments.
• Using a pitch-shifter.

Related articles:
• Top 8 Best Vibrato Pedals For Guitar & Bass
• What Are Vibrato Guitar Effects Pedals & How Do They Work?

I'll just reiterate here that vibrato is different than tremolo.

Chorus

What is chorus? Chorus is an effect that produces copies of a signal (the original signal and each of its copies has its own “voice”) and detunes each voice to produce a widening and thickening of the sound. Each voice interacts with the other voices to produce slight modulation and an overall larger-than-life sound.

Why is chorus a modulation effect? Chorus is a modulation effect because the delay time parameter of the delay line is modulated via an LFO. As delay time is modulated, the audio is time-compressed and expanded in real-time, producing a variation in pitch. The delayed signal(s) is then mixed back in with the dry signal.

The chorus effect is named after the use of chorus in music. That is, a group of people singing or playing the same note in unison. Naturally, there will be some slight pitch variation in the voices that make up the chorus. This slight detuning varies across time.

The effect is rich, adding depth and width to the sound.

Chorus modulation is achieved similarly to how vibrato is achieved: by modulating the delay time in a delay circuit. However, with chorus, the dry signal is mixed back in at the output.

So with chorus, we have the dry, unprocessed signal and one or more copies/delays of the signal that are modulated, so their pitch varies over time.

A simplified chorus unit signal path would look like this:

By modulating the delay time with an LFO, we effectively shift the phase of the delayed signal back and forth. This causes pitch variation and also causes some amount of phase-shift-induced filtering in the signal.

Combining the modulated phase-shift signal with the dry signal causes the time-varying detuned effect known as chorus.

The delay time is generally in the range of 18-24 milliseconds. This is too short to be heard as a distinct delay but also long enough so that excessive comb filtering does not occur (that's the realm of flanger effects).

Common chorus effect controls include:

• Speed/Rate: controls the frequency of the LFO and, therefore, the speed at which the pitch-variation happens in the wet signal.
• Depth/Intensity: controls the amplitude of the LFO and, therefore, the range of delay times the delay circuit will oscillate between.
• Mix: adjusts the mix between the dry (unprocessed) signal and the wet (delay-modulated) signal.
• Low-Cut Filter: a high-pass filter control that filters out modulation in the low-end that could potentially cause issues, especially in stereo chorus effects.

Let's have a look at a few examples of chorus effects units:

• Notable 500 Series chorus unit: TB Audio TBDD Stereo Chorus
• Notable 19″ rack mount chorus unit: TC Electronic 1210
• Notable chorus effect pedal: TC Electronic Stereo Chorus +
• Notable chorus Eurorack module: Feedback 106 Chorus
• Notable chorus plugin: Eventide TriceraChorus

Related articles:
• Top 11 Best Chorus Pedals For Guitar & Bass
• Top 11 Best Chorus Modulation Plugins For Your DAW
• What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work?

Flanger

What is flanger? Flanger is a modulation audio effect whereby a signal is duplicated, and the phase of one copy is continuously being shifted. This changing phase causes a sweeping comb filter effect where peaks and notches are produced in the frequency spectrum or the signal's EQ.

Why is flanger a modulation effect? Flanger is a modulation effect because the delay time parameter of the delay line is modulated via an LFO. The delayed signal is fed back into itself and mixed with the dry signal, causing a comb-filtering effect that is swept across the frequency response. This is the flanger effect.

The flanger effect was first heard by playing two identical tapes in parallel and pressing down on the flange of one of the tapes to cause a comb filter sweep across the combined output as one tape fell out of sync (became more and more delayed relative to the other).

This phase-shifting effect is easily distinguishable by its “jet plane swoosh” or “drainpipe” sounding effect.

Like vibrato and chorus, flanger is achieved by modulating the delay time of a delay line with an LFO. By modulating the delay time, the delayed signal is phase-shifted back and forth.

But instead of having the effect of pitch variation or thickening like vibrato and chorus, respectively, the flanger effect is much more of a filter-like effect.

To get the flanger effect, the delay time of the delay line must be relatively short. This will minimize the effect of adding an additional voice to the sound and maximize the phase interactions between the dry and delayed signals.

In general, we don't want to go over 20 ms, but ideally, we want the delay time to be much shorter than that to maintain a tight enough phase-shift and comb filter effect.

To understand flanger, let's quickly have a look at what phase means.

Phase applies to waveforms. In particular, it is the location of a point within a wave cycle of a repetitive waveform. A repetitive wave will go through 360º as it completes one period (one cycle). At this point, we can say the phase is 360º or 0º.

This can be shown with a simple sine wave:

A phase shift of 90 degrees can be achieved by delaying a secondary signal (like what happens with the flanger's delay path):

At 180º, mixing the two waves together will cause them to cancel each other out:

Note that each frequency has its own wavelength and period (the time it takes to complete one cycle). Therefore, a set delay time will cause some frequencies to cancel out while others will get boosted.

What we're left with is a comb filter, which gets its name from its comb-like appearance.

For example, with a 1 ms phase shift between two identical signals, we'd have the resulting comb filter across the frequency spectrum:

Now, if we were to modulate the delay time, we could sweep this comb filter across the frequency spectrum. That is, in essence, the flanger effect.

By allowing the delay path to feedback in on itself, we can further intensify the effect by producing resonant peaks in the comb filter sweep. This can be visualized below:

To end things off with flanger, I'll add a simplified signal path of a typical flanger circuit:

Common flanger effect controls include:

• Speed/Rate: controls the frequency of the LFO and, therefore, the speed at which the pitch-variation happens in the wet signal.
• Depth/Intensity/Width: controls the amplitude of the LFO and, therefore, the range of delay times the delay circuit will oscillate between.
• Delay Time: controls the set point about which the LFO will modulate about.
• Resonance/Feedback: adjusts the amount of the delayed signal that is fed back into the delay line, thereby adjusting the resonance peaks of the resulting comb filter.
• Mix: adjusts the mix between the dry (unprocessed) signal and the wet (delay-modulated) signal.

Let's have a look at a few examples of flanger effects units:

• Notable 500 Series flanger unit: Bel BF-20-500
• Notable 19″ rack mount flanger unit: MXR-126 Flanger Doubler
• Notable flanger effect pedal: Electro-Harmonix Stereo Electric Mistress
• Notable flanger Eurorack module: Doepfer A-188-1 BBD
• Notable flanger plugin: D16 Group Antresol

Related articles:
• Top 11 Best Flanger Pedals For Guitar & Bass
• Top 9 Best Flanger Modulation Plugins For Your DAW
• What Are Flanger Pedals (Guitar/Bass FX) & How Do They Work?

Phaser

What is phaser? Phaser is a modulation audio effect whereby a series of peaks and troughs are produced across the frequency spectrum of the signal's EQ. These peaks and troughs vary over time, typically controlled by an LFO, to create a sweeping effect known as phaser.

Why is phaser a modulation effect? Phaser is a modulation effect because an LFO modulates the corner frequencies of the cascaded all-pass filters (poles). As the LFO modulates the poles, the notches within the frequency response move up and down, causing the phase-shift sound of phaser.

The phaser effect causes a series of notch filters to sweep across the frequency response, creating a unique effect. It's perhaps the trickiest modulation effect to explain, but I'll do my best to explain it simply.

Rather than modulating a delay circuit, a phaser's LFO is set to modulate a series of all-pass filters. We'll get to that in a second.

The effect the phaser has on a sound is similar to flanger, except the comb filter isn't technically a comb filter. It's actually a series of notch filters that move in unison as the phaser is modulated.

Generally, the phaser's notches are fewer in number and spaced a bit differently. This is why phasers and flangers sound kind of similar but are certainly distinguishable.

Okay, let's get to the part about understanding how phasers work.

Let's begin with the all-pass filter. This is a filter that passes all frequencies but alters the phase of the frequencies across the frequency spectrum.

An all-pass filter is made of a low-pass filter and a high-pass filter that smoothly crossover at a corner frequency. They are set up so that all frequencies pass and no EQ boosts or cuts take place. However, the high-pass filter acts upon a phase-inverted signal so that the frequencies slowly change phase across the spectrum.

The corner frequency, then, is at 90º. Let's have a look at a few images to help illustrate.

Now let's string a bunch of all-pass filters together in cascade (each one feed into the next):

In the case above, we have 4 all-pass filters (also known as poles).

Let's have a look at the phase-shift graph for 1, 2, 3 and 4 pole setups:

Focusing on the 4-pole line, we see that we go 180º (completely out-of-phase) twice. This happens in the low-mid frequencies and again in the mid-ranges.

The 4-pole frequency response would look something like this, where the 180º out-of-phase frequencies show up, effectively, as notch filters.:

The more poles, the more notches (at a two-to-one ratio).

If we were to modulate the corner frequency of each stage/pole upward and downward within the audible frequency spectrum, we would sweep these notches and have ourselves a phaser effect!

Feeding the final all-pass filter output back into the first all-pass filter input will further intensify the effect by producing resonances:

And there we have, as concise and simple as I can make it. Here's an illustration of a simplified phaser signal path.

Common phaser effect controls include:

• Speed/Rate: controls the frequency of the LFO, which, in turn, controls the speed at which the comb-type filter will sweep across the signal’s EQ.
• Width: controls increase or decrease the amplitude of the LFO and, thereby, increase the range of frequencies the phaser will affect.
• Feedback/Resonance: adjusts the amount of the affected signal that is fed back through the phaser circuit, thereby increasing the resonance of each peak within the comb filter and increasing the intensity of the phaser effect.
• Stages/Poles: changes the number of poles (and therefore notches) in the phaser circuit/effect.
• Mix: adjusts the mix between the dry (unprocessed) signal and the wet (phase-shifted) signal.

Let's have a look at a few examples of phaser effects units:

• Notable 19″ rack mount phaser unit: Roland PH-830
• Notable phaser effect pedal: MXR Phase 90
• Notable phaser Eurorack module: Doepfer A-125 VC Phaser
• Notable phaser plugin: Eventide Instant Phaser Mk II

Related articles:
• Top 11 Best Phaser Pedals For Guitar & Bass
• What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?
• Top 9 Best Phaser Modulation Plugins For Your DAW

Note that uni-vibe is based on the same design principles as phaser.

What is the rotary effect in audio? The rotary effect (aka Leslie effect) was initially produced by the famous Leslie speaker, a unit with a rotating speaker. As the speaker rotates, three separate effects are produced in the [stationary] listener's ears. Those effects are tremolo, the Doppler effect (vibrato) and Phasing.

The rotary effect can be produced by a rotating speaker or with an effects unit. These effects units are essentially phasers.

Let's have a look at a few examples of rotary effects units:

• Notable 19″ rack mount rotary effect unit: Dynacord CLS-222
• Notable rotary effect pedal: Leslie Cream Simulator
• Notable rotary effect plugin: Eventide Rotary Mod

Auto-Pan

What is auto-pan? Auto-pan is a modulation effect that moves the audio signal back and forth between two positional points in the mix panorama and can be done in stereo or multi-channel mixes.

Why is auto-pan a modulation effect? Auto-pan is a modulation effect because the panning of the signal is modulated via an LFO that moves the signal between two points in the stereo (or multi-channel) image.

Common auto-pan effect controls include:

• Width: controls the variation in panning from side to side by altering the amplitude of the LFO.
• Offset: adjusts the centre point about which the auto-pan modulates.
• Rate: adjusts the speed at which the panning changes by altering the frequency of the LFO.

Let's have a look at an example of an auto-pan effects unit:

Notable auto-pan effect plugin: Soundtoys PanMan

Ring Modulation

What is the ring modulation effect in audio? Ring modulation is an amplitude modulation effect where two signals (an input/modulator signal and a carrier signal) are summed together to create two brand new frequencies, which are the sum and difference of the input and carrier signals. The carrier is typically a simple wave selected by the effects unit, while the modulator signal is the input signal.

Why is ring modulation a modulation effect? Ring modulation is effectively a type of amplitude modulation where the carrier signal has a fundamental frequency in/near the audible range (20 – 20,000 Hz). The carrier is modulated by the input to produce sidebands at the output, which are the sum and difference of the two signal frequencies.

Ring modulation is another somewhat tricky effect to explain. Let's get into it by first describing the result of the ring modulation effect.

As we'd expect, ring modulation, at its simplest, has a modulator and a carrier signal. These signals are waveforms and have frequency content. The output of the ring modulator is made of the sidebands of the modulator and carrier. That is the sum and difference of their frequencies.

The effect is most easily shown by using two sine waves. Let's say we have a 1 kHz (1,000 Hz) sine wave as the modulator:

Let's say the carrier is a 900 Hz sine wave. In this case, the ring modulator would output two new frequencies (sidebands):

• 1,000 Hz – 900 Hz = 100 Hz
• 1,000 Hz + 900 Hz = 1,900 Hz

However, most audio signals aren't sine waves and are made up of many different frequencies and harmonics. This can get rather complex, and all the sidebands are produced.

When the carrier wave is a sine wave, things remain relatively tame. Each frequency (and even the noise) of the modulator will only be split into two bands.

Things get really wild when the carrier is not a sine wave and, therefore, has harmonics. Each harmonic of the carrier will produce its own 2 sidebands from each frequency in the modulator signal.

Without getting too far down that rabbit hole, allow me to provide another illustrated example.

This time we'll look at a 100 Hz triangle wave modulator signal with only the first 4 harmonics.

Let's use a 50 Hz sine wave carrier signal in this example. The sidebands of the triangle and sine wave would be produced at each harmonic:

• 100 Hz fundamental would become:
  • 100 – 50 = 50 Hz
  • 100 + 50 = 150 Hz
• 300 Hz first harmonic would become:
  • 300 – 50 = 250 Hz
  • 300 + 50 = 350 Hz
• 500 Hz second harmonic would become:
  • 500 – 50 = 450 Hz
  • 500 + 50 = 550 Hz
• 700 Hz third harmonic would become:
  • 700 – 50 = 650 Hz
  • 700 + 50 = 750 Hz
• 900 Hz fourth harmonic would become:
  • 900 – 50 = 850 Hz
  • 900 + 50 = 950 Hz

The ring modulator output, in this example, would resemble the following:

Now let's move on to the modulation aspect.

Ring modulation is nearly identical to amplitude modulation (like the tremolo effect we discussed earlier) except for one key difference.

With ring modulation, the resulting product of the modulator and carrier flips phase as the carrier becomes negative. With amplitude modulation, there is no such phase flip. This can be visualized in the following image:

This makes it so that neither the modulator nor the carrier signals are heard at the output. It's only the sidebands. Some ring modulators offer a mix control to mix in the input/modulator signal to the output.

Relating to the tremolo effect, it's important to note that the carrier oscillator is not an LFO. It must have a much higher frequency (in the audible range) to effectively produce audible sidebands.

The actual circuit diagram of the ring modulator is where the effect gets its name since it looks like a ring. I'll add that below:

Common ring modulation effect controls include:

• Carrier Frequency: adjusts the frequency of the carrier signal.
• Wave: alters the waveform of the carrier signal.
• Low-Pass Filter: ring modulation can get rather harsh in the high-end. Some ring modulators have an LPF to deal with this.
• Mix: Mixes the dry signal in with the sidebands (the dry signal is not outputted by default with ring modulation).
• LFO Section: some ring mods have an additional LFO to control other parameters, furthering the modulation aspects of the effect.

Let's have a look at a few examples of ring modulation effects units:

• Notable 500 Series ring modulator: Meris Ottobit
• Notable 19″ rack mount ring modulator: TC Electronic FireworX
• Notable ring modulation effect pedal: Fairfield Circuitry Randy’s Revenge
• Notable ring modulation Eurorack module: Random*Source Ring
• Notable ring modulation plugin: KiloHearts Ring Mod Snapin

Related article:
• Top 8 Best Ring Modulation Pedals For Guitar & Bass
• What Are Ring Modulation Effects Pedals & How Do They Work?

Other Effects That Use Modulation

Alright, so now that we've covered the typical modulation effects, let's talk about the other effects that use modulation.

Again, these are standard effects that will have hardware and/or software dedicated to producing the effect. These effects won't generally show up in “modulation effects” categories, though modulation is required, in one way or another, to achieve the desired results.

The other effects that use modulation are:

• Vocoder
• Wah-Wah
• Auto-Wah/Envelope Filter
• Octavers

Vocoder

What is vocoding in audio? Vocoding is the process of analyzing and synthesizing the human voice (or another modulator signal) for audio transformation. A vocoder splits the modulator signal into frequency bands, and a carrier signal is filtered according to the level of the modulator in each of these frequency bands.

Why is vocoding a modulation effect? The vocoder is a modulation effect for this reason: it analyzes a modulator signal, divides it into frequency bands and applies a band-pass filter to each band. The carrier signal is split into the same bands and filters, which are raised/lowered according to the amplitude of the modulator signal.

The term vocoder is a portmanteau of voice and encoder. Vocoders are a bit of a stand-out in this article since they're better classified as an instrument than an effect. They work by analyzing and synthesizing voice signals to modulate or otherwise control other parameters.

Vocoders have plenty of applications, including, of course, being an electronic musical instrument. So, briefly, how do vocoders work?

In the case of the vocoder, we have two defined inputs. The modulator signal will be the vocal/voice audio, and the carrier signal will be a musical instrument signal (often a keyboard-based synthesizer).

A vocoder works by analyzing the modulator (the vocal/voice) signal. It does so by measuring the amplitudes of the signal within a defined set of frequency bands. These bands are largely defined by band-pass filters, though the first and last band may be defined by a low-pass and high-pass filter, respectively.

A sort of amplitude envelope is generated for each band. Each modulated band's energy (voltage in analog vocoder) is then sent to an identical set of bands/filters that govern the carrier signal. The level at which each of the carrier signal bands is outputted from the vocoder is modulated by the energy/voltage of the corresponding modulator band.

Let's have a look at a vocoder diagram to help with our explanation (note that this is an analog vocoder with voltage-controlled amplifiers, but the general design is universal):

In the above vocoder diagram, we have 10 bands. Each band/filter is doubled to achieve matching pairs of bands.

The modulator signal is sent through each of the 10 bands in parallel. Each band will analyze a specified frequency range of the signal.

The carrier signal is sent through each of its 10 bands in parallel as well.

The amplitude/voltage of each modulator band is used to control the VCA (voltage-controlled amplifier) of each matching carrier band. This means that the amplitude of the modulator bands controls the output level of the carrier bands.

So if the modulator was a single tone/sine wave that fit into only one band, the output would only contain that band's worth of the carrier signal.

By using vocal/voice signals as the modulator and some sort of synth patch as the carrier, we can modulate the synth to take on a characteristic frequency output of a vocal/voice signal while maintaining the character of the patch itself.

Noise generators can be used to help maintain some of the non-harmonic characteristics of the vocal/voice signal (sibilance, plosives, etc.) since noise is more closely related to these speech factors.

There's a lot more to know about vocoders, including the many controls, which we'll discuss shortly. However, this section should give you a solid idea of how vocoders work as modulation-based instruments.

Common vocoder controls include:

• Number of Bands: adjusts the resolution of the modulator by changing the number of frequency bands into which the modulator is split.
• Frequency Range: adjusts the limits of the carrier signal similar to a band-pass filter.
• Bandwidth: adjusts the width of each band and filter.
• Formant: shifts the frequencies (up or down) that are covered by the filters.
• Depth: the amount by which the modulator will affect the carrier.
• Unvoiced: a setting that allows sibilance, plosives and other non-harmonic voice content to more effectively modulate the carrier by adding noise to the carrier, allowing for a more intelligible vocoder effect.
• Mix: mixes the dry (unprocessed) and wet (vocoder output) together at the output.

Let's have a look at a few examples of vocoders:

• Notable vocoder: Korg microKorg
• Notable 19″ rack mount vocoder unit: Roland SVC-350
• Notable vocoder effect pedal: Boss VO-1
• Notable vocoder Eurorack module: L-1 Vocoder
• Notable vocoder plugin: Image-Line Vocodex

Wah-Wah

What is the audio wah effect? Wah (or Wah-Wah) is a filtering effect that is common on guitars and keyboard instruments. Wah is achieved by sweeping one or more boosts in EQ up and down in frequency, thereby mimicking the human vowel sound of “wah”.

Why is wah-wah a modulation effect? Wah-wah is a modulation effect because the user modulates the formant-like EQ boosts, typically with the treadle-type pedal.

Wah effects aim to achieve the same spectral glide as the human voice saying “wah” forward and backward. The modulation of the EQ peaks caused by the effect is designed to resemble the movement of formants in the natural response of the human voice.

Formants are distinctive frequencies that help define a vowel (or consonant) sound. They are particular sensitivities (increases in amplitude) at certain frequency bands. Each vowel will have its own formants, which have a bit more energy than the other frequencies in the sound wave.

Here is a graph that plots the vowel sounds according to their first and second formants.

The wah effect mimics the sound “wah-wah” by modulating a resonant peak across the frequency response of the effect's output. The modulation is controlled by a variable resistor (potentiometer) or another type of expression control. The actual filter of a swept wah effect could look something like this:

The image above shows that the resonant peak is modulated from one extreme (represented by the yellow line) to another (represented by the blue line).

Common wah effect unit controls include:

• Expression Controller: the modulation control, be it a mod wheel, expression pedal, aftertouch, etc.
• Q Controls: adjusts the width of the resonant peak.
• Range: adjusts the frequency range in which the peak will be modulated between.
• EQ (Bass, Mids, Treble): an addition tone control.
• Level: the overall output of the effect unit.

Let's have a look at a few examples of wah-wah effects units:

• Notable 19″ rack mount wah unit: Dunlop Cry Baby DCR1SR
• Notable wah effect pedal: Dunlop Cry Baby GCB-95
• Notable wah Eurorack module: D&D Modules Lord Of The Wah
• Notable wah plugin: Native Instruments Guitar Rig (as an effect)

Related articles:
• Top 14 Best Wah Pedals For Guitar & Bass
• What Are Wah-Wah Guitar Effects Pedals & How Do They Work?

Auto-Wah/Envelope Filter

What is auto-wah or envelope filtering? Auto-wah/envelope filtering is an effect in which the filter of the signal is modulated by the envelope/transients of a signal. These filters, therefore, act according to the dynamic rise and fall of a signal and are most often used on bass, guitar and synthesizer instruments.

Why is auto-wah/envelope filtering a modulation effect? Auto-wah/enveloping filtering is a modulation effect because the filter is modulated/controlled by the envelope of the signal.

As the name “envelope filter” would suggest, this modulation effect uses the envelope of the input signal's amplitude to control a filter cutoff frequency the effectively filters the output signal.

This style of modulated filtering is similar to the wah-wah effect mentioned above, except that the modulation is caused automatically by the inherent envelope of the input rather than via an expression pedal, hence the name
“auto-wah”.

An envelope filter effect unit will detect the amplitude of the input signal and generate an appropriate envelope. We can visualize this with the following image, where the black line represents the audio signal, and the red line represents the detected envelope:

This envelope will modulate the filter of the effect unit. A low-pass envelope filter will look something like the following (notice how the minimum and maximum envelope markers match up):

The filter will generally have a resonance peak at the cutoff frequency to achieve the wah-like spectral glide, as depicted above.

Envelope filters can utilize band-pass, high-pass or low-pass filters, which can be swept upward or downward for various effects.

Common envelope filter controls include:

• Filter Type: low-pass, band-pass or high-pass.
• Response/Attack: adjusts the attack time of the generated envelope.
• Speed/Decay: adjusts the decay time of the generated envelope.
• Sensitivity: adjusts the amount of amplitude needed to achieve the same amount of filtering.
• Range: adjusts the range of the filter movement across the envelope.
• Q/Peak: adjusts the resonance peak at the cutoff frequency.
• Sweep Direction (Up/Down): changes the direction of the sweep.
• Mix: mixes the dry (unfiltered) and wet (envelope filtered) signals together at the output.

Let's have a look at a few examples of envelope filter effects units:

• Notable 500 Series envelope filter unit: Moog The Ladder Envelope Filter
• Notable 19″ rack mount envelope filter unit: Mutronics Mutator
• Notable envelope filter effect pedal: Mu-Tron Micro-Tron IV
• Notable envelope filter plugin: Kuassa Efektor WF3607

Related articles:
• Top 13 Best Envelope Filter Pedals For Guitar & Bass
• What Are Envelope Filter Effects Pedals & How Do They Work?

Octavers

What is the octaver effect? The octaver/octave effect is an audio effect that effectively adds one or more octaves (below or above) to the signal.

Why is the octave effect a modulation effect? Some octave effect effects utilize amplitude modulation with generated square wave carrier signal(s) that are octave(s) from the input fundamental. These carriers then affect copies of the input signal to raise or drop the signal by one or more octaves, resulting in a less “synthy” sound.

Note that simple monophonic octave generation can be achieved with modulation, though pitch-shifting and harmonization effects cannot. These effects require sampling and DSP to work efficiently in real-time. Today, the vast majority of octave effects also use more accurate DSP technology.

Let's have a look at an example of an octave effects unit:

• Notable modulation-style octaver effect pedal: Boss OC-5

However, if you're interested in learning about pitch-shift and harmonization effects, check out my articles:
• Top 9 Pitch-Shifting & Harmonizer Pedals For Guitar & Bass
• What Are Pitch-Shifting Guitar Pedals & How Do They Work?

Other Uses Of Modulation In Audio

Though this article isn't necessarily about modulation in general, I thought it would be nice to finish with a few more examples of modulation in the context of audio.

We've discussed the effect. Now let's briefly mention a few other ways in which modulation is used.

Voice modulation refers to any variation in the strength, tone, or pitch of someone's voice. We can see how similar this natural effect is to many of the audio effects discussed above.

To modulate, in music theory, is to change keys within a piece of music.

Though getting into each and every possible modulation scheme for the wireless transfer of audio would take a while, I should mention some of the main ways in which modulation can be used for wireless audio (note that there are different modulation types within the following styles of wireless transmission):

• AM (Amplitude Modulation) Radio
• FM (Frequency Modulation) Radio
• Wireless Audio Transmission Via Radio Waves
• Bluetooth Wireless Audio Transmission

Related articles:
• How Do Wireless Headphones Work? + Bluetooth & True Wireless
• How Do Wireless Microphones Work?
• How To Connect A Wireless Microphone To A Computer (+ Bluetooth Mics)

As we've briefly discussed, synthesizer instruments utilize modulation in all sorts of ways to shape the output audio signal. Here are a few ways in which modulation is used in synths:

• FM (Frequency Modulation) Synthesis
• Synthesizer Modulation Controls
  • LFOs
  • Envelope Generators
  • Modulation Wheels
  • Aftertouch
  • Step Sequencers
  • Knobs/Faders
  • Expression Pedals

A Special Note On FM Synthesis

I figured I couldn't discuss vocoders without discussing FM synthesis since they're both instruments. Let's end this article by briefly discussing FM synthesis.

What is FM synthesis? Frequency modulation synthesis is a type of sound/audio synthesis that utilizes modulating oscillators to modulate the frequency of the audio/carrier waveform. Many complex harmonic and inharmonic sounds are possible with this type of synthesis.

Isn't frequency modulation synthesis just vibrato, then? Absolutely not!

Remember that the vibrato effect actually modulates the delay time in a delay signal. It achieves its pitch variation by compressing and expanding the period of the waveform.

FM synthesis uses its modulator signals to alter the frequency of the carrier itself, making it a completely different type of modulation.

That being said, we can use the pitch-varying effect to help us understand the nature of FM synthesis.

The first thing to note is that vibrato uses an LFO modulator. The variations in pitch, then, are easily perceived.

If the modulator oscillator in an FM synth had a low enough frequency (in the LFO range), we would also hear a variation in the pitch of the synth output.

But what happens as we increase the modulator frequency? The modulation of pitch begins to quicken until it becomes unnoticeable. Around the 20 Hz cutoff point, we begin hearing an increasing modulator frequency as a change in timbre rather than a quickening of pitch variation.

The higher the modulation frequency, the more complex the synthesized output waveform.

So by modulating the frequency of a waveform with an oscillator in the “audible frequency range”, we actually alter the tonality of the waveform and, thereby, synthesize new audio signals and sounds.

This is, of course, an oversimplification, but it's a good start to understanding the basics of FM synthesis.

Choosing the best audio plugins for your DAW can be a challenging task. For this reason, I've created My New Microphone's Comprehensive Audio Plugins Buyer's Guide. Check it out for help in determining your next audio plugin purchases.

Building out your 500 Series system can be a challenging task. For this reason, I've created My New Microphone's Comprehensive 500 Series Buyer's Guide. Check it out for help in determining your next 500 Series purchases.

The post Complete Guide To Audio Modulation Effects (With Examples) first appeared on My New Microphone and is written by Arthur Fox.

Ring modulation is one of the weirdest effects a guitarist could add to their pedalboard. The intriguingly odd sounds we can get out of a ring mod pedal have likely sparked your interest and inspired you to check out this article, where you'll learn how they work.

What are ring modulation pedals, and how do they work? Ring Modulation pedals are stompbox units designed for guitar and/or bass. They modulate the amplitude of the input signal with a carrier signal (typically a sine or square wave) in order to produce/output new frequencies, which are the sum and difference (sidebands) of the input and carrier signals.

The resulting output signal from a ring modulator can be wildly different from the input signal. These pedals are quite experimental by nature and can be very exciting to use (and talk about).

In this article, we’ll further our understanding of ring modulation and the pedals that produce this strange effect. I’ll share a few pedal examples along the way and tips on how to get more out of your ring mod pedals.

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use
• Top Best Ring Modulation Pedals For Guitar & Bass

Table Of Contents

• What Is Ring Modulation?
• What Are Ring Modulation Pedals & How Do They Work?
• The Control Parameters Of Ring Modulation Pedals
• Tips On Using Ring Mod Pedals
• Where Should A Ring Modulation Pedal Go In The Signal Chain?
• Other Amplitude-Modulation Effects
• Related Questions

What Is Ring Modulation?

Ring modulation is a type of amplitude modulation signal processing function. It utilizes a carrier wave and a modulator wave and produces multiple frequencies from these two signals. The frequencies produced are the sidebands (the sums and differences of the frequencies of the carrier and modulator signals).

To put it more straightforwardly, ring modulation multiplies two input signals together to create two brand-new frequencies, which are the sum and difference of the input frequencies.

Ring modulation utilizes two input signals: the modulator and the carrier. The modulator is nearly always the instrument input signal, and the carrier is a signal produced by the ring modulator.

A device capable of ring modulation is referred to as a ring modulator. These electronic devices are most often seen with synthesizer units or modules. As the title of this article suggests, they are also designed in the form of guitar pedals.

The label of “ring modulation” is derived from the analog circuit that produces the effect. This circuit utilizes several diodes in the shape of a ring, as is shown below:

The diodes in the circuit either face clockwise or counter-clockwise, depending on the schematic.

As we can see from the basic diagram above, we have an “input” modulator signal and another “carrier” input signal.

In the case of guitars (and other instruments), the modulator (labelled “input” in the picture above) signal will be the instrument signal, and the carrier signal will be a waveform provided by the ring modulator. The carrier signal is typically a basic waveform (a sine, triangle, square, sawtooth or similar).

Basic Waveforms & Their Harmonic Content

As an aside, each basic waveform has its own harmonic characteristics. A harmonic is an integer multiple of the wave/signal/sound's fundamental frequency (note value). These harmonic characteristics will help us to understand ring modulation better and can be summed up in the following:

• Sine waves (green) have a single frequency (the fundamental).
• Square waves (blue) have infinite odd-order harmonics (3x, 5x, 7x,.. the fundamental frequency) and each successive harmonic has less amplitude.
• Triangle waves (red) also only have odd-order harmonics though the amplitude reduction of each successive harmonic is much greater.
• Sawtooth waves (orange) have infinite even and odd-order harmonics (2x, 3x, 4x, 5x,.. the fundamental frequency) and each successive harmonic has less amplitude.

Once again, the carrier signal is produced by the ring modulator itself.

You may have trouble with the terminology difference between modulator and carrier. I certainly did when I first got into ring modulators. I remember it this way: the carrier is ever-present in the ring mod unit, and the guitar/instrument input signal is modulating the ever-present carrier.

As we'll discuss shortly, the effect of ring modulation doesn't discriminate between modulator and carrier. However, to be technically correct, the carrier is the signal produced by the ring mod unit.

The Ring Modulation Effect

The ring modulator's output is made of the sum and difference frequencies of the modulator and carrier waves. This is the same as with amplitude modulation, except that ring modulation does not output the carrier signal, nor does it output the modulator signal.

Note that some ring modulator pedals will have a wet/dry mix, which can re-introduce the dry/direct (carrier) signal. However, the ring mod circuit itself does not output the carrier (or the modulator) signals.

The easiest explanation is possible with a sine wave modulator and a sine wave carrier. Let's say the modulator has a frequency (f_m) of 1,500 Hz, and the carrier has a frequency (f_c) of 700 Hz. Remember that sine waves only have a single frequency.

The output of the ring modulator would have two new frequencies that are the sum and difference (sidebands) of the two input signals. They would be:

• f₁ = f_m + f_c = 1,500 + 700 = 2,200 Hz
• f₂ = f_m + f_c = 1,500 – 700 = 800 Hz

Before we get too into it, it's important to note that the audible range of frequencies is 20 Hz – 20,000 Hz. Any sidebands outside this range are typically filtered out of a ring mod unit since we cannot hear them, anyway! This helps free up headroom and prevents clipping.

Let's further our understanding of the ring modulation effect by looking at a few other examples.

Let's start with sine wave carriers and modulators since they are easy to visualize.

In our first illustrated example, let's have a 1 kHz sine wave modulator. The frequency response is shown below:

What happens if we send this modulator wave through a ring modulation circuit with a carrier wave also set as a 1 kHz sine wave? Remember that the output would be the sum and difference of the signals' frequencies. Therefore, we'd have:

• 1 kHz – 1 kHz = 0 Hz (no signal)
• 1 kHz + 1 kHz = 2 kHz

The first sideband is 0 Hz, and so the output will only have one frequency.

Note that the original 1 kHz modulator wave and the 1 kHz carrier are not present in the output signal. Rather, the 1 kHz modulator is simply outlined to represent the “instrument” input in the following graphs:

What happens if we use a 500 Hz sine wave as the carrier for our 1 kHz (1,000 Hz) modulator? We'd have:

• 1,000 Hz – 500 Hz = 500 Hz
• 1,000 Hz + 500 Hz = 1,500 Hz

In this case, the ring modulator acts as it's supposed to, creating two new frequencies within the audible range, as shown below:

As another example, let's see how a 900 Hz sine wave carrier signal will affect our 1 kHz (1,000 Hz) modulator:

• 1,000 Hz – 900 Hz = 100 Hz
• 1,000 Hz + 900 Hz = 1,900 Hz

That's all good, but guitar signals are not sine waves. They have a rather complex harmonic structure with different transient/envelope information for each harmonic (each harmonic will begin at a different amplitude and decay at a different rate). How would this work as a modulator signal?

We'll get into the harmonic character of guitars later in this article.

For now, in order to get the basic idea, let's look at a simpler wave: the triangle wave. Recall that the triangle wave has only odd harmonics, and each successive harmonic has less amplitude than the last.

To keep things clean in this example, let's limit the number of harmonics to 4.

We'll use a 100 Hz triangle wave with only 4 harmonics as our modulator. The harmonics are at 300, 500, 700 and 900 Hz. The following frequency graph represents this triangle wave:

Let's now look at how a ring modulator would affect this 100 Hz triangle modulator wave with a 50 Hz sine wave carrier.

Sidebands would be produced at each harmonic:

• 100 Hz fundamental would become:
  • 100 – 50 = 50 Hz
  • 100 + 50 = 150 Hz
• 300 Hz first harmonic would become:
  • 300 – 50 = 250 Hz
  • 300 + 50 = 350 Hz
• 500 Hz second harmonic would become:
  • 500 – 50 = 450 Hz
  • 500 + 50 = 550 Hz
• 700 Hz third harmonic would become:
  • 700 – 50 = 650 Hz
  • 700 + 50 = 750 Hz
• 900 Hz fourth harmonic would become:
  • 900 – 50 = 850 Hz
  • 900 + 50 = 950 Hz

An 80 Hz sine wave carrier would cause the following:

• 100 Hz fundamental would become:
  • 100 – 80 = 20 Hz
  • 100 + 80 = 180 Hz
• 300 Hz first harmonic would become:
  • 300 – 80 = 220 Hz
  • 300 + 80 = 380 Hz
• 500 Hz second harmonic would become:
  • 500 – 80 = 420 Hz
  • 500 + 80 = 580 Hz
• 700 Hz third harmonic would become:
  • 700 – 80 = 620 Hz
  • 700 + 80 = 780 Hz
• 900 Hz fourth harmonic would become:
  • 900 – 80 = 820 Hz
  • 900 + 80 = 980 Hz

Something interesting happens with a 100 Hz sine wave carrier. The upper sideband of one triangle wave frequency matches with the lower sideband of the following frequency. We could say that this ring modulator is “tuned”. It would look something like this:

• 100 Hz fundamental would become:
  • 100 – 100 = 0 Hz (no audio)
  • 100 + 100 = 200 Hz
• 300 Hz first harmonic would become:
  • 300 – 100 = 200 Hz
  • 300 + 100 = 400 Hz
• 500 Hz second harmonic would become:
  • 500 – 100 = 400 Hz
  • 500 + 100 = 600 Hz
• 700 Hz third harmonic would become:
  • 700 – 100 = 600 Hz
  • 700 + 100 = 800 Hz
• 900 Hz fourth harmonic would become:
  • 900 – 100 = 800 Hz
  • 900 + 100 = 1,000 Hz

Ring modulators may sound very “harmonic” when the carrier and modulator signals are harmonically related and work together to boost harmonic partials of the input signal. Of course, the output frequency response will be different than either input. However, it may very well be similar, harmonically speaking.

The effect will produce an inharmonic output when the carrier and modulator frequencies are not harmonically related (which is often the case with a guitar ring mod pedal). This is what gives the ring modulator its characteristic bell-like/metallic/strange sound.

If we brought the carrier sine wave up to 1,000 Hz to ring-modulate our 100 Hz triangle modulator wave, we might be thinking, by our previous calculations, that we'd have negative output frequencies (100 – 1,000 = –900, for example).

This is a perfect opportunity to discuss a key part of ring modulation: it doesn't matter which signal is the carrier and which is the modulator when it comes to frequency splitting. That being said, in a ring mod pedal, the guitar signal is always the modulator, and the internally generated signal is the carrier.

The main point I want to make is that, to the ring mod (and to our ears), a “negative frequency” will perform just like a “positive frequency”. As we move a sideband across the 0 Hz threshold into the negative, the sideband will actually begin creeping up, and once it passes the 20 Hz threshold or “–20 Hz”, we'll begin hearing it again.

So, then we should look at the sidebands of the sine wave carrier and each of the modulator harmonics to get a better picture of what's actually happening:

• 1,000 Hz carrier and 100 Hz modulator fundamental sidebands:
  • 1,000 – 100 = 900 Hz
  • 1,000 + 100 = 1,100 Hz
• 1,000 Hz carrier and 300 Hz modulator 1st harmonic sidebands:
  • 1,000 – 300 = 700 Hz
  • 1,000 – 300 = 1,300 Hz
• 1,000 Hz carrier and 500 Hz modulator 2nd harmonic sidebands:
  • 1,000 – 500 = 500 Hz
  • 1,000 + 500 = 1,500 Hz
• 1,000 Hz carrier and 700 Hz modulator 3rd harmonic sidebands:
  • 1,000 – 700 = 300 Hz
  • 1,000 + 700 = 1,700 Hz
• 1,000 Hz carrier and 900 Hz modulator 4th harmonic sidebands:
  • 1,000 – 900 = 100 Hz
  • 1,000 + 900 = 1,900 Hz

So rather than having this:

The ring modulator will output this:

So a ring modulator will take each and every harmonic of the carrier signal and output the sidebands produced from every harmonic of the modulator signal.

This is relatively simple to visualize with a single-frequency sine wave as the carrier but gets more difficult to imagine with multi-frequency carriers.

Many ring modulators will utilize a sine wave as their carrier signal. However, some will utilize other waveforms. This can get tricky. Let's say the carrier is a square wave (with infinite odd-order harmonics). Each harmonic will cause its own sideband.

We can utilize the basic concept of additive synthesis to help us understand the effect of ring modulation more clearly.

With additive synthesis, each harmonic of a synthesized sound is produced by its own sine wave, dedicated to that frequency. So then, a more complex signal, like that of a guitar signal modulator or a square wave carrier, can be thought of as a collection of individual sine waves at different frequencies.

In this context, each individual frequency/sine wave of one signal (modulator or carrier) is affected by every frequency/sine wave of the other signal to produce sidebands. These sidebands, as we've discussed, must be positive (there are no “negative frequencies”), and they should fit within the audible range of human hearing (between 20 Hz and 20,000 Hz).

Modulating, say, a sawtooth wave (infinite even and odd-order harmonics) by a square wave (infinite odd-order harmonics) would yield very involved sidebands and a complex output, indeed.

The purpose of these exercises is to be thorough in our investigation of the ring modulation effect.

Guitar signals have complex harmonic profiles made even more interesting with polyphony (multiple notes at once in a chord) and with overdrive/compression/distortion (which adds harmonics to the signal).

For example, a major triad would have, at the very least, 3 different fundamental frequencies (though some notes may be doubled up in a guitar chord) along with all the harmonics that go along with these fundamentals. Each of these frequencies would be affected by the carrier, and sidebands would be produced from each and every frequency.

Most ring modulators will use a sine wave carrier signal to keep the effect relatively “tame”. However, it's important to understand how a square wave (or another waveform) would act as a carrier signal in a ring modulator.

A Discussion On Ring Modulation Waveforms

Ring modulation can also be visualized in terms of waveforms.

Let's have a look at a sine wave carrier (top) with frequency x; a sine wave modulator (middle) with frequency 16x, and the resulting ring-modulated product (bottom):

Notice how the resulting product flips phase as the carrier becomes negative. This is part of ring modulation and the major difference between ring modulation and “regular” amplitude modulation.

By flipping the phase when the carrier is negative, the ring modulation circuit effectively eliminates the modulator signal from the output. As we'll discuss shortly, this is the main difference between a ring modulation circuit and an amplitude modulation circuit.

Let's now look at a sine wave carrier (top) with frequency x; a square wave modulator (middle) with frequency 16x, and the resulting ring-modulated product (bottom):

This process of “frequency mixing” in ring modulation is known as heterodyning. A heterodyne is a signal frequency that is created by combining or mixing two other frequencies together.

This “splitting” of the signals' frequencies/harmonics is possible to achieve via analog means. Some distortion may occur due to the forward voltage drop of the diodes. However, this multiplication is much easier (and cleaner) in digital systems using rather simple DSP.

By that token, we can have either analog or digital ring modulation pedals. Most ring modulation pedals, though, are analog.

The Electro-Harmonix Frequency Analyzer XO is a great example of an analog ring modulator pedal.

The Strymon Mobius is a digital multi-effect pedal focused on modulation-type effects. It has an awesome ring modulation setting accessed via the AM (amplitude modulation) mode in its Quadrature mod machine type.

Ring Modulator Vs. Voltage Controlled Amplifier

If you happen to be coming from a more synthesizer-based background of understanding, perhaps relating a ring modulator to a VCA could help develop your knowledge of ring modulation.

A VCA allows one signal to pass when another signal is “present”. In the case of a VCA, the control voltage signal (analogous to the “carrier”) is in charge of passing the audio input signal (analogous to the “modulator”).

VCAs are often controlled by envelopes or LFOs (low-frequency oscillators) to shape the amplitude of a synth patch.

If the control voltage/modulator is maxed, the entire carrier is passed through. If either the CV or the input signal is at 0 volts, there will be no output.

If the CV is negative (below 0 volts), no carrier signal shall pass through to the output.

Here's an illustration of a VCA signal flow graph:

VCAs are called 2-quadrant multipliers because they handle both positive and negative voltages/amplitudes in the audio/carrier input, but only positive voltages/amplitudes on the modulation input. This results in no output when the modulator runs at and below 0 volts.

Ring modulators, by contrast, are referred to as 4-quadrant multipliers or “balanced modulators” since they can negative and positive voltages/amplitudes in both the carrier and modulator input signals.

Like the VCA, the ring modulator's carrier signal “allows” the modulator to pass at various amplitudes. However, when the carrier drops to a negative voltage/amplitude, it still passes the modulator.

The catch here is that the phase of the modulator is inverted when the carrier is negative. Remember that we're multiplying signals, and multiplying a negative by a negative yields a positive, while multiplying a negative by a positive yields a negative.

Here's an illustration of a ring modulator signal flow graph:

To further visualize the differences between a VCA and a ring modulator, let's look at illustrations of waveforms.

Below, we have a representation of a VCA to the left and a ring modulator to the right.

The VCA has a sine wave CV with frequency x (top), while the ring modulator has a sine wave carrier with frequency x (top). Each has audio/modulator signals with a frequency of 8x (middle). The difference in output signals (at the bottom) are shown:

As another example, we have a VCA to the left and a ring modulator to the right. This time there is a sine wave CV/carrier with frequency x (top) and a square wave audio/modulator with a frequency 8x (middle). The output signals (at the bottom) are shown:

Ring Modulation Vs. Amplitude Modulation

Another great way of describing ring modulation is to contrast it against straight-up amplitude modulation.

Amplitude modulation is often used to produce a tremolo effect when its carrier signal frequency is in the LFO range (from well below 1 Hz to under 20 Hz). Amplitude modulation is also used in AM radio, where the carrier signal frequency is in the AM radio range (about 550 to 1720 kHz).

Ring modulation and amplitude modulation are similar but not exactly the same.

The key difference in the resulting output between RM and AM is that AM keeps the original modulator signal frequencies in the output. As we've discussed, ring modulation removes the original modulator frequencies from the output, leaving only the sum and difference frequencies of the carrier and modulator.

This happens because a ring modulator's carrier signal will actually go into negative and affect the polarity of the modulator signal.

A regular amplitude modulation carrier will remain positive and acts to modulate the peaks/troughs (amplitude) of the modulator wave. This unipolar carrier (which means the entirety of the signal is above 0 V) is made possible by applying a positive DC offset voltage to the carrier signal.

Below, we have a representation of RM to the left and AM to the right. Each has a sine wave carrier with frequency x (top) and a modulator with a frequency of 8x (middle). The difference in output signals are shown at the bottom:

Notice that the 0 volts line (the horizontal black line) is different from the carrier signal of the AM illustration. This represents the unipolar nature of the AM modulator wave. The entirety of the AM carrier is above 0 V, while the RM carrier is negative half the time.

Here, we have another representation of RM to the left and AM to the right. Each has a sine wave carrier with frequency x (top) and a square wave modulator with a frequency of 8x (middle). The difference in output signals are shown at the bottom:

That was a lot of information. Let's recap to help simplify!

Ring modulation has two inputs and one output.

The first input is called the modulator and is generally the audio signal. This is the case with ring modulation guitar pedals.

The second input is a bipolar waveform generated by the ring mod unit. It's generally a basic waveform (most often a sine wave) and has a frequency in the audible range, most often sweepable in the range of 20 Hz to 4,000 Hz.

The output of the ring modulation circuit is made of the sidebands of these two input signals. Sidebands are made from the sum and difference between each frequency of the modulator and each frequency of the carrier.

A sine wave (single frequency wave) carrier will produce two sidebands with each harmonic/fundamental frequency of the modulator input signal.

A square wave (or another more harmonically complex carrier wave) will produce many sidebands with each harmonic/fundamental frequency of the modulator input signal.

What Are Ring Modulation Pedals & How Do They Work?

Now that we understand what ring modulation is, let's get into ring modulation pedals and how they work.

A ring modulation pedal is simply a ring modulation unit with the form factor of an instrument stompbox. These pedals are typically designed for guitar signals but can also work on other instruments. They also generally have controls to alter their functionality, which we'll get to momentarily.

Once again, the ring modulation circuit gets its name from its basic layout, which looks like a ring of clockwise (or counter-clockwise) diodes.

The basic ring modulation circuit resembles the following:

There are two inputs and one output in the basic ring mod circuit:

• Modulator (input)
• Carrier (input)
• Output

Ring Modulator Input: Modulator

The input signal (also known as the modulator) is the guitar signal.

Ring Modulator Input: Carrier

The input signal produced by the ring modulation pedal is referred to as the carrier. This carrier signal is either produced digitally or via a voltage-controlled oscillator and is typically a sine wave or another basic wave shape.

A ring mod pedal will allow us to alter the frequency on the VCO/carrier signal, and some even allow us to change the sine wave to another waveform (often a square wave).

Like an AM radio signal carrier, this carrier wave is ever-present (when the pedal is turned on). It is ready to be modulated by the modulator (guitar input) signal.

A ring mod pedal will generally offer a large range of possible carrier frequencies. We can typically sweep through this range via a “frequency” knob.

Some ring mod pedals even have a “low” function that drops the carrier frequency down into the LFO (low-frequency oscillator) range, allowing the pedal to double as a sort of tremolo.

Ring Modulator Output

The output of the ring modulation circuit is made of the sidebands (sum and difference) of the input/modulator signal and carrier signal frequencies.

The Harmonic Profile Of A Guitar Signal

As we've discussed, the ring modulation pedals are typically designed for guitar signals. Let's briefly discuss the harmonic content of a guitar signal.

Know that different instruments have different harmonic profiles and frequency responses. These differences give the various instruments unique timbres/tones even when they play the same exact note.

There are plenty of ways to alter a guitar's tone (EQ, wah, compression, distortion, modulation). Any change in signal tone going into the ring modulator will yield a difference in sidebands due to the alteration in the guitar's frequencies.

That all being said, a vibrating guitar string will produce both odd and even-ordered harmonics.

Generally, the first harmonic (an octave above the fundamental) will be the highest in amplitude. The fundamental frequency and second and third harmonic will typically be a bit lower in amplitude but very present in the signal.

Above the third harmonic, each successive harmonic has less amplitude than the one before it. This goes on until about the 16th harmonic, where the following harmonics get a slight boost in amplitude.

Above the 24th harmonic, the amplitudes become so low that they're barely identifiable. Harmonics well before the 24th are largely ignored in analysis though they are responsible for the timbre of the vibrating guitar string.

Even harmonic will have its own amplitude envelope as part of the string's timbre. The higher harmonics will die out much faster than the fundamental and lower harmonics, which sustain as the string vibrates.

Of course, this is just the basics of a vibrating guitar string. Factors such as the guitar body material, string material and tension, note(s) being played, electromagnetic pickup, tone and volume control, patch cable, other effects units, amplifier(s), and others will affect the actual frequency response of the guitar.

A 6-string guitar in standard tuning will have its lowest fundamental frequency at 82 Hz at E₂ (the open low E string). Most pickups will have a frequency response extending to 8 kHz or lower in the high-end. Most amplifiers and cabinets will cut high frequencies even below that.

So if we have a ring modulator pedal with a sine wave carrier, we'll get two sidebands for each of the guitar's partials/harmonics. These harmonics and fundamental frequencies will generally be within the range of 82 Hz to about 8,000 Hz.

A square wave carrier will produce many more sidebands and may cause an overly distorted sound at the output, given a guitar signal's already rich harmonic nature.

The Ring Modulation Circuit

Without getting into the weeds of particular schematics, let's look at the basics of the ring mod circuit. To help us visualize, I'll bring back the circuit illustration for a third time:

The 4 clockwise-facing diodes are effectively set up as 2 pairs. One pair is made of the “top and bottom” diodes, while the other is made of the “left and right” diodes.

As the bipolar (AC) carrier signal alternates between positive and negative current, it will cause, at any given time, one pair of diodes to conduct electricity while reverse-biasing the other pair.

The conducting pair allows the modulator (input) signal to travel from the secondary transformer winding at the input to the primary transformer winding at the output.

When the carrier signal is in the positive part of its waveform, it causes the top/bottom pair of diodes to conduct based on the amplitude of the carrier. This allows the modulator to pass but restricts its amplitude to the waveform of the carrier.

When the carrier signal is in the negative part of its waveform, it causes the left/right pair of diodes to conduct based on the amplitude of the carrier. This allows the modulator to pass with restricted amplitude (based on the amplitude of the carrier) but flips the polarity between the transformers.

Once again, this can be visualized in the following illustration, where the carrier sine wave (top) affects the amplitude and polarity of the modulator square wave (middle) to produce the output (bottom). Notice the polarity shift in the output as the carrier dips below 0:

This causes the ring modulation circuit to eliminate the modulator signal frequencies from the output and effectively splits the frequencies between the modulator and carrier signals at the output.

Note that other ring modulation units may utilize digital signal processing (DSP) to achieve the same effect. Here, the frequencies of the two inputs are detected and used to sum and subtract the two output frequencies mathematically.

Low-pass filters and oversampling are often used in digital ring mods to avoid aliasing and distortion in the output signal.

The Control Parameters Of Ring Modulation Pedals

Let's now turn our sights onto the common control parameters we'll find on a ring modulation pedal. This will give us further insight into how ring modulation pedals are designed and how they function as effects units.

Common ring modulation pedal controls include:

• Carrier Frequency
• High/Low (Speed)
• Wave
• Filter
• Mix
• LFO Section

Carrier Frequency

The carrier frequency control is rarely ever labelled as “carrier frequency”. However, it's always a parameter we can control on a ring modulation pedal.

As the descriptor suggests, the “carrier frequency” control will alter the frequency on the carrier signal (which is either a sine or another basic waveform).

The frequency range of a ring mod carrier is in the audible range of frequencies, typically in the lower range between about 20 Hz to 4,000 Hz (rather than all the way to the upper audible limit of 20,000 Hz).

These controls are often labelled simply as “frequency”. Other pedals offer coarse and fine-tuning adjustments for the carrier frequency.

The Electro-Harmonix Ring Thing offers both coarse and fine-tuning of its carrier frequency.

High/Low (Speed)

In our discussion of general amplitude modulation, we touched on the similarities between tremolo and ring modulation.

To recap, tremolo is essentially ring modulation with a very low carrier frequency. Ring modulation, then, is pretty much the same as tremolo, only with a much faster “LFO”. While we can actually hear the modulation of the amplitude in tremolo, we hear the AM of ring modulation as an alteration of harmonic content.

To improve functionality, some ring mod pedals offer a “tremolo setting” by allowing users to toggle between a “high-frequency” carrier and a “low-frequency” carrier (LFO). Note that each setting will have its own range that we can sweep through with the aforementioned carrier frequency control.

The Fairfield Circuitry Randy's Revenge allows us to toggle between ring modulation carrier frequencies (HI) and tremolo LFO frequencies (LO). The frequency control (FREQ) applies to both.

Wave

As we've discussed, most ring modulation utilizes a simple sine wave as its carrier frequency. These single-frequency waveforms offer a single split of each harmonic/partial of the input (modulator signal).

However, for those ring mod pedals that offer options for the carrier wave, a control will allow us to toggle between the various carrier waveforms.

The frequency can be altered for each carrier waveform.

The Way Huge Ringworm offers a whopping 5 different modes with 3 different carrier waveforms, an envelope and random.

Filter

The frequency multiplying/splitting can get rather convoluted in the high-end of the pedal's output.

Remember that harmonics are integer multiples, but the frequency spectrum is logarithmic. Therefore, the upper octave(s) will have more harmonic content. Sometimes this content is overly harsh and ill-defined. A low-pass filter can effectively rid of this information and clean up the signal.

Note that guitar pickups will often only have a frequency response up to 6 – 8 kHz, so the high-end information is not typically heard anyway. It's okay, then, to filter it out!

Mix

Some ring modulation pedals allow us to mix the dry/direct signal back in with the output of the ring mod circuit. This brings up closer to a typical amplitude modulation output.

LFO Section

Some ring modulation pedals will have a separate low-frequency oscillator (with frequency, waveform and amplitude controls).

This LFO is generally used to modulate the carrier frequency and, therefore, the output frequencies of the ring mod circuit output.

The Moog Moogerfooger MF-102 (now discontinued) has an entire section dedicated to its LFO.

Tips On Using Ring Mod Pedals

Ring modulation pedals are certainly strange. They may even be downright troublesome to get a usable sound out of.

Here are a few tips to get the most out of your ring modulation pedal:

• Set the carrier frequency to match the key
• Double it as a tremolo pedal
• Bring in some direct signal
• Express yourself
• Read the manual
• Play to the pedal

Set The Carrier Frequency To Match The Key

Ring modulation is known for being rather “inharmonic” and “unmusical”. However, we can “tune” these pedals to become somewhat harmonic within a limited range of notes.

We can do so by adjusting the carrier frequency to match the fundamental or lower harmonic of the notes we're playing.

Let's say we're playing in the key of A (the open A string of a guitar has a fundamental frequency of 110 Hz in A₄ = 440 Hz tuning). Setting the ring mod carrier frequency to 110 Hz should give us a harmonic/musical sound so long as we stay within the constraints of A and its first few harmonics.

In the example of A 110 Hz, we'd have the following harmonics:

• Fundamental: 110 Hz (A₂) = root
• 1st harmonic: 220 Hz (A₃) = root
• 2nd harmonic: 330 Hz (E₄ – 2 cents) = perfect fifth
• 3rd harmonic: 440 Hz (A₄) = root
• 4th harmonic: 550 Hz (C#₅ + 14 cents) = major third
• 5th harmonic: 660 Hz (E₅ – 2 cents) = perfect fifth

So long as we stay within the confines of the root, perfect fifth and major third, the output of the ring mod should remain pretty harmonic.

To learn more about the relationships between musical notes and frequencies, check out my article Fundamental Frequencies Of Musical Notes In A=432 & A=440 Hz.

Double It As A Tremolo Pedal

As mentioned, some ring modulation pedals offer a “low-frequency setting” in which their amplitude-modulating circuit becomes a tremolo rather than a ring mod.

It should come as no surprise that ring modulation isn't an effect we typically leave on like, say, a compressor. So then, when we don't need the ring mod effect, we can set the pedal to “tremolo mode” and get a two-in-one effect.

Bring In Some Direct Signal

If the ring mod pedal offers any sort of mix control, we can dial in some of the direct signal.

By dialling in some dry signal, we can effectively hear the actual notes we're playing. This can also make the effect less pronounced in the overall mix, making it more of an accent than the main attraction in your playing.

Express Yourself

If the ring modulation pedal has an expression input, use it!

Being able to control the carrier frequency or LFO of the ring mod pedal can really be a great benefit in getting the most out of the strange effect.

Read The Manual

In all likelihood, the pedal manufacturer's manual will tell you more about the specific ring modulation capabilities of the pedal than this article ever could.

Reading the manual can give you great insight into the pedal and how to get the most out of it. It may even give you the knowledge required to dial in settings exactly how you hear them in your head!

Play To The Pedal

Ring modulation is a strange effect. Sometimes strange effects need strange riffs/lines to reach their full potential.

Wonderwall will likely sound awful through a ring modulator. However, writing something weird could fit perfectly with the ring mod effect.

Playing to the pedal is something I also suggest for synth pedals when Blues licks just don't do the effect justice.

By playing to the pedal, we can open up a whole new realm of creativity centred around our ring mod pedal.

Where Should A Ring Modulation Pedal Go In The Signal Chain?

Ring modulation pedals sound pretty experimental, so my advice is to experiment with the positioning in the pedal chain.

Modulation effects often sound best near the end of the pedal chain just before time-based effects (delay and reverb). However, ring modulation pedals aren't our typical modulation effects pedals (chorus, flanger, phaser, etc.).

I've gotten cool results using a ring mod at the very end of the chain (yes, even running delay into it). I've also got cool results with it at the front of the chain and in the middle.

Chances are that the ring mod pedal will be used sparingly for special effect rather than as a mainstay in your tone. Therefore, it can be fun to experiment with its placement to get the coolest effects possible.

If your ring mod pedal doubles as a tremolo pedal and you plan on using it as both, then perhaps putting it after the dynamic, pitch-shifting, synth and gain-based effects would work best. This still allows for plenty of placement options, especially with larger signal chains.

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other Amplitude-Modulation Effects

Now that we've discussed ring modulation pedals and how they work, essentially, as amplitude modulators. Let's look at other pedals that alter the amplitude of the signal to produce their effects.

Other pedal types that are designed primarily to alter the amplitude of the signal are:

• Tremolo
• Volume

Note that many pedals will have volume/level controls. However, most pedals aren't designed to affect amplitude specifically.

Tremolo Pedals

Tremolo pedals can be thought of as ring modulation pedals with LFOs (low-frequency oscillators) rather than modulation signals in the audible frequency range.

The LFO of a tremolo pedal alters the signal's amplitude, bringing the signal up and down in level. It does so at a rate that is heard as actual amplitude modulation rather than an additional pitch (as is the case with ring modulation).

Technically speaking, even an LFO-range carrier frequency will split the input into two sets of harmonics. However, the frequency difference and sum between the two sets are so small that we don’t hear it as a difference in pitch.

That being said, the effect of tremolo can be heard as altering the amplitude of the signal at a fast rate.

The Electro-Harmonix Stereo Pulsar is an example of a stereo tremolo pedal.

To learn more about tremolo pedals, check out the following My New Microphone article:
• What Are Tremolo Guitar Effects Pedals & How Do They Work?

Volume Pedals

Volume pedals are generally designed as expression pedals (with treadle-type foot controller). They control to volume or amplitude of the signal passing through their circuit.

This volume control is achieved by means of attenuation rather than by applying gain.

Volume pedals are easy to understand. Depending on how the pedal is set up, the expression pedal will allow maximum signal in either toe-down or heel-down position and no signal at the opposite position.

Volume pedals do not only allow for muting, which is great between songs, while tuning, etc. They also allow for volume swells and other changes in dynamics due, in large part, to their continuously variable nature.

The Ernie Ball VP JR. is a popular volume pedal with a relatively small footprint (hence the name “Jr.”).

Related Questions

Is chorus a modulation effect? Chorus is considered to be a part of the modulation category of effects. It utilizes a modulated delay circuit to produce pitch-variation in the wet signal and combines the wet and dry/direct signals at the output to produce a multi-voice “chorus” effect.

What is the difference between chorus and flanger? Chorus and flanger are both based on the same basic design: a modulated delay circuit that causes phase modulation in the output signal (a mix of the wet and dry signals). The chorus effect sounds like multiple voices with slight detuning, while the flanger effect sounds like a whooshing/sweeping of the phase. The major differences in design are:

• Flangers typically only use two voice (wet and dry). Chorus may have multiple wet voices (though a 2-voice effect is also common).
• Flangers have shorter delay times (below 10 ms) while choruses have longer delay times (above 10 ms). There is crossover between these values.
• Flangers utilize a feedback loop in the delay circuit while choruses do not.

To learn more about chorus and flanger pedals, check the following My New Microphone articles:
• What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work?
• What Are Flanger Pedals (Guitar/Bass FX) & How Do They Work?

The post What Are Ring Modulation Effects Pedals & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

No effect brings the funk quite as much as the envelope filter. The wah-wah comes close, but its “automatic” cousin reigns supreme. For both guitar and bass, the magic of the envelope filter can easily be found inside small stompbox effects pedals.

What are envelope filters, and how do they work? An envelope filter pedal (also known as auto-wah) is a stompbox unit that triggers a dynamic filter. This filter can be a low-pass, band-pass, or high-pass and acts according to the amplitude of the input signal. These pedals are typically designed for guitar or bass guitar.

In this article, we’ll develop our knowledge of envelope filters pedals, discussing the inner workings of these pedals and how they affect guitar and bass guitar signals. I’ll share a few envelope filter pedals throughout the article and offer some tips on how to get the most out of your auto-wah pedal(s).

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

Table Of Contents

• What Is An Envelope Filter?
• What Are Envelopes?
• A Look At Different Audio Filters
• What Are Envelope Filter Pedals & How Do They Work?
• Controls On Envelope Filter Pedals
• Tips On Using An Envelope Filter Pedal
• Where Should An Envelope Filter Pedal Go In The Signal Chain?
• Other EQ Modulation Effects
• Related Questions

What Is An Envelope Filter?

An envelope filter can be understood by separating the two words.

The first word is envelope. An envelope, put simply, describes a signal or sound's change over time.

Envelope generators are common in synthesizers and samplers. These are the circuits that produce the framework of a signal's attack, decay, sustain and release.

Envelope generators are often used to define the amplitude of a key when pressed, held and released. They can also be used to affect many other parameters, including, of course, filters.

Envelopes also define acoustic sounds. The initial transient and subsequent sustain of a sound are due to its envelope.

Of course, the envelopes of acoustic sounds are not programmed synthetically. However, with subtractive synthesis, we can use envelope generators to emulate the natural envelope of a sound to produce a synth patch that sounds like an instrument.

The second term is filter. A filter effectively alters the frequency response of a signal by either reducing or removing frequency above/below certain points along the frequency spectrum.

A filter, then, can alter the sound quite dramatically by changing its harmonic character. Filters are a major part of EQ.

To learn more about EQ pedals, check out my article What Are EQ Pedals (Guitar/Bass) & How Do They Work?

An envelope filter is a sort of dynamic EQ. It is a filter controlled by an envelope.

The envelope filter will read its input signal and use it to produce a corresponding envelope. This envelope will then act upon a filter to alter its cutoff frequency/frequencies in order to sweep it across the audible frequency spectrum.

That's the basic definition of an envelope filter: a filter controlled by an envelope.

Let's deepen our understanding by discussing envelopes, filters and, of course, envelope filters in greater detail.

What Are Envelopes?

No, we're not talking about the envelopes at the post office.

In terms of sound and audio, an envelope describes how a sound changes over time. It is typically related to amplitude, though envelopes can also apply to filters, pitch and other effects and parameters of a sound/signal.

This article will focus more on how envelopes can describe/affect the filter of an audio signal.

Envelopes happen naturally in the world and can also be generated via electronics.

Sound sources produce transients: short-duration, high amplitude peaks at the beginning of their waveforms.

Here's an illustration of a sound/audio wave transient:

Notice how that amplitude peaks and quickly comes down. This peak represents the picking, slapping, and even just the touching of a string. The more percussive we play or, the harder we hit the strings, the more pronounced the transient.

These peaks typically contain a great deal of harmonic content that defines the timbre and tone of the sound.

The higher harmonic content loses energy faster than the lower content (the note's fundamental frequency is generally the last to fade).

Combine this with the reduction of overall amplitude as the string vibrations get weaker and weaker, and we have ourselves an envelope.

In fact, if we were to really get into it, we could develop an envelope model for each frequency of a sound. This is how additive synthesis aims to recreate real instruments.

Speaking of synthesis, we can also produce envelopes electronically. Again, these envelope generators are often related to amplitude, though envelopes can also apply to filters, pitch, and other effects and parameters of the signal.

These envelope generators are commonplace in synthesizer and sampler designs. They are also used in envelope filter pedals to control an audio filter.

Like many audio effects, these envelope generators can be either analog or digital and can be built into hardware (analog and digital) or software (digital only).

The typical envelope generator has four parameters: attack, decay, sustain and release. Let's have a look at a simple illustration of ADSR and describe each of the variables.

• Attack: the time the audio takes to go from zero amplitude to peak amplitude as the note is played. This ties in closely with the transient.
• Decay: the time the audio takes for the subsequent run down from the attack level/amplitude to the designated sustain level/amplitude.
• Sustain: the level of the sound/amplitude after the attack and decay, which is maintained until the key is released.
• Release: the time taken for the level to decay from the sustain level to zero after the note is released.

The above graph shows an envelope as it relates to the amplitude of a signal. Envelopes can also be generated to control other parameters.

In the case of an envelope filter circuit, the signal is filtered according to its transient/envelope information.

A Look At Different Audio Filters

Let's have a quick look at a few audio filters to better understand how an envelope filter shapes the sound.

When the term “filter” is used, it generally refers to the elimination of certain frequencies from a signal. In the case of an envelope filter, we generally will see low-pass, high-pass or band-pass filters.

To get the “auto-wah” sound we love out of an envelope filter, the filter must have two characteristics:

• A resonant frequency where the filter EQ peaks, producing a boost of a certain narrow band of frequencies. This mimics the formants natural to speech and gives us that wah-like sound.
• A sweepable centre frequency for the filter that moves according to the signal dynamics. This sweeps the filter and the filter resonance to give us the movement required of a wah/auto-wah.

I write more extensively on vocal formants and their role in wah-wah circuits in my article on wah pedals: What Are Wah-Wah Guitar Effects Pedals & How Do They Work?

There are 5 basic filters we should understand in audio. Envelope filters will typically use [the first] 3 of the following, so I'll give a bit more explanation of the first 3 in the paragraphs below. The 5 filter types are:

• High-pass filter
• Low-pass filter
• Band-pass filter
• Band-reject filter
• All-pass filter

High-Pass Filter

The high-pass filter is perhaps the most commonly-used pass-type filter in mixing.

High-pass filters “pass” the high-frequencies above their cutoff frequency while progressively attenuating frequencies below the cut-off frequency. In other words, high-pass filters remove low-frequency content from an audio signal below a defined cut-off point.

Sweeping a high-pass filter will either remove more or allow more low-end to pass through to the output. Here's another look at a high-pass filter, this time with a resonant frequency at its cutoff. Remember that the resonant peak will produce the formant-like peak required to produce the wah-wah effect:

To learn more about high-pass filters, check out my article Audio EQ: What Is A High-Pass Filter & How Do HPFs Work?

Low-Pass Filter

Low-pass filters are the opposite of high-pass filters. They “pass” the low-frequencies below their cutoff while progressively attenuating frequencies above their cutoff. In other words, low-pass filters remove high-frequency content from an audio signal above a defined cut-off point.

Sweeping a low-pass filter will either remove more or allow more high-end to pass through to the output. Here's another look at a low-pass filter, this time with a resonant frequency at its cutoff. Remember that the resonant peak will produce the formant-like peak required to produce the wah-wah effect:

To learn more about low-pass filters, check out my article Audio EQ: What Is A Low-Pass Filter & How Do LPFs Work?

Band-Pass Filter

A band-pass filter is like a combination of a low-pass and high-pass filter. It passes a band of frequencies (a defined range with a low cutoff and a high cutoff) while progressively attenuating frequencies below the low cutoff and above the high cutoff.

Band-pass filters, then, pass a band of frequencies while removing those on either side.

Sweeping a band-pass filter one way will pass more high-end while removing more low-end. Sweeping it the other way will do the opposite. Here's another look at a band-pass filter, this time with a resonant frequency at its cutoff. Remember that the resonant peak will produce the formant-like peak required to produce the wah-wah effect:

To learn more about band-pass filters, check out my article Audio EQ: What Is A Band-Pass Filter & How Do BPFs Work?

Band-Reject Filter

A band-reject filter, often referred to as a notch filter, is kind of like the opposite of a band-pass filter.

A band-reject filter works by removing frequencies in a specified band within the overall frequency spectrum. It allows frequencies below the low cutoff point to pass along with frequencies above the high cutoff point.

Band-reject filters can be used to great effect in EQ since they can remove problem frequencies within a signal. However, they are not used in envelope filters.

To learn more about band-reject/band-stop filters, check out my article Audio EQ: What Is A Band-Stop Filter & How Do BSFs Work?

All-Pass Filter

All-pass filters are odd. They actually do not filter any frequencies in terms of amplitude. They pass all frequencies.

Rather, they work by affecting the phase of any given sinusoidal component (frequency) according to its frequency.

All-pass filters, in terms of guitar and bass pedal effects, are used in phaser pedals to affect the phase of the copied signal. We’ll discuss phaser pedals and their relation to EQ later in this article.

All-pass filters aren't used in envelope filters or EQ.

What Are Envelope Filter Pedals & How Do They Work?

Envelope filter pedals are stompbox-type units designed to affect bass and guitar signals through they can also be utilized on other instruments.

Their basic circuits include an envelope detector and an adjustable filter.

The envelope detector reads the input signal, which produces a coinciding envelope that closely represents the characteristic attack and sustain of the note(s) being played.

The detector defines the input signal as its average change in voltage over time.

Here's a simple illustration of a dynamic signal and its resulting envelope:

This envelope is then used to control the filter's position (whether it's a high-pass, low-pass or band-pass) across the frequency spectrum.

The Electro-Harmonix Q-Tron+ envelope filter pedal offers options between low-pass (LP), band-pass (BP), high-pass (HP) and a mix (BP + dry signal). The filter type is selectable via the “mode” dial.

When the envelope reaches its peak, the filter will be moved to one extreme of its overall range. As the envelope comes to its minimum value, the filter will be at the other extreme of its overall range.

Let's have another look at that envelope and how it could affect a low-pass-type filter:

The range, envelope detector sensitivity, sweep direction and filter type can often be adjusted within the pedal. We'll get to envelope filter pedal parameters shortly.

As we've discussed briefly in the section on filters, an envelope filter should require a resonant peak to produce a wah-wah-like sound (which is what we typically want out of our envelope filter).

Envelope filters are often referred to as “auto-wahs” since they produce a wah-like effect without the need for an expression pedal. The amplitude envelope of the input signal effectively acts as our expression pedal in this comparison.

We'll discuss wah pedals in more detail in the section Other EQ-Modulation Effects.

So, the basic circuit of an envelope filter would look something like this:

Let's start with the easy part. Some envelope pedals have a mix/blend knob that allows some direct/dry (unaffected/unfiltered) signal to be mixed in at the pedal's output. Other pedals may not allow for this, but it's worth mentioning.

So then, some envelope filters are even simpler, looking something like this:

Next, we have input signal go into an audio filter section and an envelope detector section. The signal simultaneously has an envelope created to represent its amplitude and has a filter applied to it that is controlled by the envelope.

As the envelope amplitude increases and decreases, the filter (along with its resonant frequency) moves up and down in the frequency spectrum.

Therefore, the harder we play, the more intense the effect becomes.

Note that some envelope filters offer 2 directional modes. In this case, the “up” mode is configured so that an increase in the envelope amplitude causes an upward motion in the sweep. Conversely, the “down” mode would be configured so that an increase in the envelope amplitude produces downward motion in the sweep.

The Maxon AF-9 offers adjustable sweeping directions (in the drive control) along with 3 different filter types, range selection, sensitivity, and peak controls.

Note that, in either mode, the filter can still be HP, LP or BP.

Controls On Envelope Filter Pedals

To really comprehend the inner workings of an envelope filter, we should understand the typical parameters we can control.

Common envelope filter pedal controls include:

• Filter Type
• Response/Attack
• Speed/Decay
• Sensitivity
• Range
• Q/Peak
• Sweep Direction (Up/Down)
• Mix

Filter Type

As we've mentioned, envelope filters can be designed with 3 basic filter types: low-pass, band-pass and/or high-pass.

In envelope filters that offer multiple filter types, the choices will be selectable on the pedal. This is typically achieved via a toggle switch.

Once again, here are a few illustrations of the three main envelope filter types (each with a resonance frequency):

Response/Attack

The response or “attack” control will alter the way the envelope detector reacts to an incoming signal.

Increasing the attack/response will slow down the envelope's attack and make the initial sweep slower as a note is struck.

So rather than having this:

We'd have something like this:

Note that controls labelled as “response” may also affect the envelope's decay, which brings us to our next point.

Speed/Decay

The speed control (sometimes referred to as “decay” or “release”) is similar to the attack control, except it acts up the decay of the envelope.

Increasing the decay or decreasing the speed would draw out the decay portion of the pedal's envelope.

So instead of having this:

We'd have something like this:

Attack and decay/release controls can also be seen on compressor pedals and other pedals.

Related article: Dynamic Range Compression: Attack & Release Controls

Sensitivity

Sensitivity refers to how much the incoming signal will affect the envelope and, therefore, the signal filtering.

Lower sensitivity ratings require more input signal (harder playing or a louder guitar/bass) to trigger the same level of filtering. Higher sensitivity ratings will produce the same amount of filtering with less signal strength at the input.

Range

The range parameter refers to the sweeping range of the envelope filter. A larger range typically yields a more noticeable effect as the resonant peak is swept over a wider range of frequencies (at a faster “frequency-shift per time”).

Q/Peak

Q is a dimensionless quantity that refers to the narrowness (or width) of an EQ boost/peak. In the case of an envelope filter, the Q/ determines how sharp or smooth the resonant frequency peak is, though it doesn't alter the overall boost at the resonant frequency.

Peak controls will alter the relative amplitude spike at the resonance frequency/

The Q/peak controls can also be consolidated into a single control labelled as “resonance”.

Here's an illustration of the Q factor that should help us to visualize what Q controls do:

Sweep Direction (Up/Down)

The sweep direction (sometimes referred to as drive) is pretty self-explanatory. It switches the direction of the filter sweep between an upward sweep (the envelope triggers the resonant frequency to increase) and a downward sweep (the envelope triggers the resonant frequency to decrease).

Mix

The mix control is not always featured on an envelope filter.

This control (sometimes referred to as “blend” or “wet/dry”) controls the relative amount of the filtered signal and dry/direct signal at the pedal's output.

The MXR M82 Bass Envelope is one of the best for getting a funky auto-wah on the bass guitar. It features 4 of the 8 parameters we've mentioned (the dry and FX controls both have to do with the mix).

The Mojo Hand Wonder Filter covers the other 4 control parameters mentioned here (filter type, attack, range, sweep direction/drive).

Tips On Using An Envelope Filter Pedal

Envelope filter pedals can produce superb tones when used correctly. Getting the most out of the pedal depends largely on your playing style and dialling in the settings appropriately.

That being said, there are a few tips I should share when using envelope pedals. They are:

• Give it a break
• Spend some time to dial it in
• Play fast and play slow
• Try it after an overdrive or compressor pedal
• Read the manual

Give It A Break

This seems counter-intuitive. However, because envelope filtering is such a noticeable effect (unlike, say, a static EQ or compressor), we can actually get more out of it by using it less.

Save the envelope filter for sections of the song that need it the most. Bringing the effect in and out will make it that much more exciting when it is engaged.

Spend Some Time To Dial It In

From the envelope detector to the filters, these pedals are highly tunable.

The signal going into the pedal will be different from guitar to guitar and bass to bass. It will also be affected by all the other pedals that come before the envelope filter.

Take some time to really tune the pedal to suit your playing.

Play Fast And Play Slow

This ties into the previous point. If you're playing slowly, try adjusting the response (slower attack and speed/delay setting) to suit your playing. Conversely, set response times faster when playing busier sections.

Try It After An Overdrive Or Compressor Pedal

An overdrive or compressor pedal will reduce the dynamic range of the signal going into the envelope filter, which will, in turn, produce a more consistent signal level across all notes on the guitar or bass. This will trigger a more consistent envelope, which may sound better across a wider range of notes.

Overdrive pedals have the advantage of adding extra harmonics to the high-end of the signal, which gives the envelope filter more frequencies to be filtered.

To learn more about overdrive pedals, check out my article Guitar Pedals: Boost Vs. Overdrive Vs. Distortion Vs. Fuzz.

Read The Manual

Hopefully, reading the manual will teach you, in detail, what the pedal does and how to get the sounds you need out of it.

With an envelope filter, it's best to understand the settings that work best for you. These pedals are a bit less experimental since they sound lacklustre when not set up to suit their input signals.

Check out the manual for tips and tricks on your own envelope pedal to get the most out of it.

Where Should An Envelope Filter Pedal Go In The Signal Chain?

Envelope pedals typically sound best when put near the front of the pedal chain since they affect the EQ and tonal characteristics of the signal.

However, if you’re running utility (buffers, tuners), synth, and/or pitch-shifting pedals, an envelope filter will likely perform better when put after these pedals.

It’s also common to put envelope filter pedals after distortion-type pedals (including overdrive and fuzz) to get a fatter tone. However, putting the envelope filter before the distortion may allow increased reactivity and more harmonic content in the high-end.

Envelope filter pedals generally sound better when put before modulation and time-based effects.

That all being said, experiment with the position of your envelope pedal within the pedal chain to find the best spot for your rig.

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other EQ Modulation Effects

Now that we understand envelope filter pedals, let’s have a look at other effects that utilize variations in a signal’s frequency response:

• Wah Pedals
• Phaser Pedals

Wah Pedals

Wah pedals are stompbox-style units with treadle-style expression foot pedals designed to receive guitar, bass or other instrument signals. Their circuits are designed to modulate the formants of the sound by modulating one or more resonance peaks in the signal’s frequency response. Wah pedals do the with the use of filters and EQ.

These pedals work the same way as envelope filters, except the sweeping is done manually via an expression pedal rather than automatically by a tweakable envelope detector.

The Vox V847A wah pedal.

To learn more about wah pedals, check out my article What Are Wah-Wah Guitar Effects Pedals & How Do They Work?

Phaser Pedals

You may be thinking to yourself, “but phaser is a phase-modulating effect”. Well, that’s the category it fits into, and indeed a phaser does modulate the phase of its signal. However, the way it achieves this effect is largely based on modulation EQ.

Phaser pedals produce their distinguished effect by modulating a series of all-pass filters. Yes, all-pass filters are filters that pass all frequencies and do not actually really filter anything. This seems strange, I know.

An all-pass filter works, at least in a phaser, by splitting the input signal in two, phase-inverting one copy, and then sending the dry signal through a low-pass filter and the inverted signal through a high-pass filter (or vice versa).

The result is that all frequencies pass through, but the phase of these frequencies changes. Phasers string multiple all-pass filter “stages” together and modulate the cutoffs of the all-pass filters’ HP and LP filters to produce their effect.

So then, technically speaking, phasers are EQ-modulation pedals, too.

The Electro-Harmonix Small Stone is a simple example of a phaser pedal.

To learn more about phaser pedals, check out My New Microphone's article What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

Related Questions

Do I need a compressor pedal? Compressor pedals help balance out the dynamic of our playing by reducing the dynamic range of the audio signal. They are by no means necessary, though they may help increase perceived loudness; add sustain; improve transients, and make the guitar or bass fit better in the mix.

Related article: What Are Compressor Pedals (Guitar/Bass) & How Do They Work?

Where should I put my preamp pedal in my chain? Preamp pedals will work well anywhere in the signal chain so long as they're before the guitar or bass amp's power amplifier. That being said, they typically work best at the front of the pedal chain, where they can act on a relatively clean and low-level guitar/bass signal.

The post What Are Envelope Filter Effects Pedals & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

Wah is one of the most famous effects for guitar, and wah pedals are among the most expressive to play through. The sound of wah can be heard across many genres and on plenty of records, and wah pedals can be found on pedalboards and jam spaces around the world.

What are wah pedals, and how do they work? Wah pedals are nearly always expression-based pedals (they have a treadle-style control) and work by modulating the EQ of the signal to produce an almost vowel-like “wah” sound in the guitar (or another instrument) signal. Wah achieves this effect by sweeping bell-type peaks across the EQ.

In this article, we'll focus on understanding wah pedals and how they affect our guitar signals. I’ll share a few wah pedals as examples and offer some tips on how to get the most out of your wah pedal(s).

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

Table Of Contents

• What Is The Wah-Wah Effect?
• What Are Wah Pedals & How Do They Work?
• Potential Parameter Controls For Wah Pedals
• Tips On Using A Wah Pedal
• Where Should A Wah Pedal Go In The Signal Chain?
• Other EQ Modulation Effects
• Related Questions

What Is The Wah-Wah Effect?

The wah-wah effect (or simply “wah”) is a frequency-filtering effect for guitar, bass, and other instruments. It provides us with a way of producing a spectral glide in instruments that typically wouldn't be capable of such a thing.

A spectral glide, in music, is loosely defined as the modification of the vowel quality of a tone.

This “vowel quality” is largely defined by the frequency response and overtones of a sound wave (or audio signal). So then, a spectral glide effectively alters the frequency response and overtones of a sound/signal. As it is a glide, these characteristics move continuously from one characteristic vowel quality to another.

This is most obviously heard in human speech.

The sound of each vowel is largely defined by its formants.

Formants are distinctive frequencies that help define a vowel (or consonant) sound. Each vowel will have its own formants, which have more energy than the other frequencies in the sound wave.

As humans, we need to hear these formants to distinguish between different phonemes and understand language.

Here is a chart of IPA (International Phonetic Alphabet) vowels with their typical formants:

What do these vowels sound like? It's often best to use examples to describe the sounds of vowels. However, words are pronounced differently depending on a person's accent. Rather than trying to list out word examples (of which there are none from the English language), I'll share a link to Wikipedia where you can listen to each of the listed vowel sounds, among others.

Here is a graph that plots the vowel sounds according to their first and second formants.

So we can alter the formants of our vocals quite easily by shaping our lips, mouth and tongue. We can effectively produce the wah-wah effect by simply saying “wah-wah”.

Horns can also achieve an acoustic wah-wah effect with the use of a mute. Altering the position of the mute at the bell of the horn will alter the formant characteristics of the sound.

Brass instruments can produce some modification of vowel quality: the larger the mouthpiece, the better in this regard.

The didgeridoo is another notable acoustic instrument capable of producing a variety of different formants.

Woodwind instruments offer a bit of acoustic formant modulation, but it's really not remarkable.

Strings, like those on guitar and bass, are practically incapable of producing vowel-like sounds. Of course, we're talking about acoustics here and the sound produced by the vibration of a string.

This is where the wah-wah effect pedal comes into play. This electronic device can affect the guitar's (or bass's) audio signal to produce a wah-wah effect that would be impossible to produce acoustically.

We'll get to wah pedals and their inner workings in a moment. For now, let's discuss the term “wah-wah”.

The wah-wah effect is named after an onomatopoeia. The effect is simply what it sounds like. That's why I went through the trouble of explaining formants and vowels earlier.

Saying the phrase, “wah-wah” may seem simple. We're only tasked with repeating a single syllable twice. However, if we break it down further, there are plenty of sounds to pass through in the phrase.

“Wah-wah”, when slowed down, could be made to sound like:

“oo”-“wa”-“ah”-“oh”–“ow”-“oo”-“wa”-“ah”-“oh”–“ow”

In IPA, it could be u-w-ɑ-ə-ɒ-æ-oʊ-aʊ-u-w-ɑ-ə-ɒ-æ-oʊ-aʊ (or something along those lines). That's a lot of formant modulation for a relatively simple phrase.

The wah-wah effect, electrically speaking, aims to emulate these formant changes by effectively filtering the signal to produce the resonances required.

Wah extends the magic of the spectral glide to stringed instruments, though i can certainly use used to affect other audio sources as well.

What Are Wah Pedals & How Do They Work?

Now that we have a solid idea of what the wah effect is, let's turn our attention to the main discussion of this article. That is the wah pedal.

Wah pedals are stompbox-style units with treadle-style expression foot pedals designed to receive guitar, bass or other instrument signals. Their circuits are designed to modulate the formants of the sound by modulating one or more resonance peaks in the signal's frequency response. Wah pedals do the with the use of filters and EQ.

Before we dive in, let's have a look at a wah pedal. Pictured below is one of the many famed Cry Baby Wah Pedals from Dunlop. This one, in particular, is the Dunlop Cry Baby GCB-95.

We see that the Cry Baby has a treadle-style foot pedal that allows us to rock back and forth between heel-down and toe-down positions.

At tow-down, there is a footswitch typical of most guitar/bass pedals that, when pressed, turns the pedal on or puts the pedal in bypass mode. Note that most wah pedals will require a bit of extra force to engage their on/bypass switches. This allows the user to rock all the way the pedal all the way to the toe-down position without turning the pedal on and off each time.

The treadle/rocking pedal is connected to a potentiometer that effectively controls the spectral glide of the guitar (or other instrument) signal and produces the wah-wah effect.

The question, then, is how does this all work? Let's get into it without diving into complex circuit analysis (I'll leave that to the electrical engineers).

The most important circuit of a wah pedal, when it comes to the effect itself (really, the entire design is critical to the pedal), is the filter.

The filter is either:

• A bandpass filter.
• An overcoupled lowpass filter that exhibits a resonant peak at its lowpass roll-off frequency.

As the name suggests, a band-pass filter passes a band of frequencies while cutting the frequencies below and above the defined band. It can be thought of as a combination of a high-pass filter and a low-pass filter.

In order to achieve the wah effect, the filter must produce a distinct resonance. This mimics the effect of a formant and gets us close to a vowel-like sound.

A low-pass filter passes low-frequencies while removing high-frequencies above its cutoff point. By over-coupling a LP filter, we can produce a resonance (increase in energy) at its cut-off frequency just before the higher frequencies begin getting cut out.

Turning a wah pedal on engages this band-pass or low-pass circuit (depending on the pedal design).

Here's a simple illustration of a band-pass filter with a resonant frequency :

And here's a simple illustration of an over-damped low-pass filter:

The band-pass filter (or low-pass filter) circuit is typically an LC (inductor-capacitor) circuit with a variable resistor (potentiometer). Of course, it's more complex than that, but this LC circuit is the basic design.

The fixed inductor plays a role in the sonic nature of the pedal. It's partly responsible for determining the smoothness or aggressiveness of the sweep.

The fixed value of the capacitor also plays a tone-shaping role. Smaller capacitors increase the sweeping range while larger capacitors decrease it.

All this talk about sweep brings us to the variable resistor.

The treadle of the wah pedal controls the variable resistance of the potentiometer. As the resistance is altered, the centre point of the filter is shifted upward and downward across the frequency spectrum.

On top of that, the value(s) of the variable resistor shapes the sharpness or resonance of the wah effect. Higher resistance values narrow the resonance (increase Q) to make the peaks sharper while lower resistance values widen the resonance (decrease Q) to make the effect less distinct.

So then, rocking the pedal between heel-down and toe-down positions will sweep a resonant frequency across the frequency spectrum.

As we've discussed in the early parts of this article, resonances sound an awful lot like formants. Sweeping formants in speech give us different vowel sounds. Sweeping resonances in a guitar or bass signal give us the wah-wah effect!

The actual filter of a swept wah pedal would actually look something like this:

The yellow response curve represents the heel-down position, while the dark blue response curve represents the toe-down position. The other curves represent certain instances during the sweep.

As the resonant frequency sweep along the response, it causes a “waaaoooh” sound from heel-to-toe as the resonant frequency glides upward, and a reverse “hooooaaaaw” sound from toe-to-heel as the resonant frequency glides downward.

Some pedals allow us to switch the direction of the pedal's effect on the frequency response.

So all wah pedals are built on the same premise:

• Some sort of filter that has a resonant frequency and that removes high-end content from the signal (typically a band-pass or low-pass).
• This filter is swept up and down the frequency response to create the spectral glide effect known as wah-wah.

The main differences between the various wah pedals on the market have to do with the parameters.

Q or quality factor is a major parameter. This affects the sharpness of the resonant frequency. Higher Q values make the resonant boost narrower and produce a sharper, more aggressive sound. Lower Q values widen the resonant boost and bring up more of the surrounding frequencies, resulting in a smoother sound.

Some pedals offer Q control.

The Xotic XW-1 is a great example of a wah pedal with adjustable Q.

The other big parameters include the sweeping range or how far the resonant frequency can be swept (from the lowest possible frequency to the highest) and the type of filter being used (band-pass or low-pass).

Many wah pedal designs utilize a mechanical gear-type connection between the treadle pedal and the potentiometer.

The Vox V847A is a popular wah pedal. We can see its mechanical gear/tooth link underneath the foot pedal in the picture below:

Some other wah pedals, often referred to as “switchless wahs”, utilize optical methods (the use of light) to connect the foot pedal to the potentiometer.

The Morley PWO is an example of such an optical wah:

In a way, a wah pedal could be thought of as a foot-controlled tone knob, like the one (or several) found on your guitar. This comparison works at a surface level. However, wah pedal designs generally have a much more pronounced effect on the signal's frequency response than tone knobs.

Before we move on, I want to address a key point.

In the earlier parts of this article, I discussed the vocal formants for a number of different vowel sounds. Each vowel sound had two distinct formants. These formants represent the high-energy frequencies of whatever the vowel sound may be.

We've likened these formants to the resonant frequencies of wah pedal circuits.

However, as we've discussed, wah pedals only have one resonant frequency or “electronically-produced formant”. Therefore, while the wah pedal sounds similar to a voice saying “wah”, it's technically quite different.

This was worth mentioning to help clear up any confusion.

Potential Parameter Controls For Wah Pedals

Wah pedals, like most effects pedals, have controls to alter their performance.

The most obvious control is the expression pedal. Practically all wah pedals have this control (or an input to connect an external expression pedal). Many wah pedals actually only have this single control.

However, for those that have more, this section will help explain.

Potential parameter controls for wah pedals include:

• Expression Pedal
• Q Controls
• Range
• EQ (Bass, Mids, Treble)
• Level

Expression Pedal

The expression pedal is the treadle/rocking pedal seen on practically all wah pedals.

This pedal controls a potentiometer inside the wah pedal that sweeps the resonant frequency of the wah filter up and down the frequency spectrum. It is the main control of the wah pedal.

Most wah pedals will have their on/bypass button under the toe of the expression pedal. This allows us to effectively turn the pedal on and off by pressing just a bit harder while in tow-down position.

Q Controls

The Q (quality factor) is a dimensionless unit that represents the width of the resonance peak. High Q values produce a narrower, more aggressive boost in the wah pedal's filter, while low Q values produce a wider, more mellow boost in the filter.

Note that the Q doesn't affect the amount of boost at the peak though it does affect the residual boost of nearby frequencies.

The Q is a major determining factor in the wah's overall character.

Range

The range control will affect the overall range of the wah filter's sweep. It could shift the entire sweep up or down the frequency spectrum and/or it could increase or decrease the overall range.

EQ (Bass, Mids, Treble)

Some wah pedals include an additional EQ circuit with static EQ controls. This can help improve the overall mix of the wah pedal by cutting some of the harsh frequencies and/or boosting some frequencies that need to be heard.

The EQ circuit of a wah pedal is typically put after the wah circuit in terms of signal flow in order to help “clean up” any ill effects of the wah.

Level

The level control brings the overall output of the wah pedal up or down in amplitude.

Tips On Using A Wah Pedal

Wah pedals are among the most expressive in the world. These instantly recognizable yet highly versatile pedals can be used in many different ways.

Here are a few tips to get the most out of your wah pedals:

• Give it a break
• Sync up your hands and feet
• Rock to the rhythm
• Keep the pedal toward the front of the pedal chain
• Try it out stationary
• Clean up with EQ after the fact

Give It A Break

As discussed, wah is very noticeable when applied to guitar.

It can be used to a greater effect if we were to only engage it during musical parts that would truly benefit from its effect. It may be counter-intuitive, but we can actually get “more” out of our wah pedal by using it less.

Sync Up Your Hands And Feet

A wah pedal offers plenty of versatility with its treadle-style pedal.

A lot of expression can come from synchronizing the notes your play with the motion of the treadle. Take this tip in whatever way suits you best.

Perhaps you could rock back and forth each time a new note is played; maybe you could rock the pedal one way each note and reset before playing a new note. Find what works best for expressing your playing.

Rock To The Rhythm

Working the pedal to the song's tempo is another great way to get more out of your wah pedal.

This technique sounds awesome when combined with more percussive and funky styles of playing.

Keep The Pedal Toward The Front Of The Pedal Chain

Though I always encourage experimentation when it comes to music, keeping the wah pedal near the front of the pedal chain (but after synth, fuzz, and pitch-shifting pedals) can get you a better sound out of your wah and from your rig overall.

Try It Out Stationary

Parking a wah pedal at a stationary position along its tread can yield an interesting EQ on the signal that can get us a different sound from our instrument. Setting it so that the resonance frequency fills a spot in the mix can be a great way to make the guitar pop out for certain passages of music.

This is yet another way to get more out of your wah. It doesn't always have to be modulating!

Clean Up With EQ After The Fact

Wah pedals are awesome but sometimes they can get a bit piercing as their resonance peak crosses certain frequency bands. Too much energy at any frequency band can cause issues that are unpleasant to the ear.

To counteract these harsh frequencies, we can reduce them after the way pedal with a selective EQ.

To learn more about EQ pedals, check out my article What Are EQ Pedals (Guitar/Bass) & How Do They Work?

Where Should A Wah Pedal Go In The Signal Chain?

Wah pedals typically sound best when put near the front of the pedal chain since they affect the EQ and tonal characteristics of the signal.

However, if you're running utility (buffers, tuners), synth, and/or pitch-shifting pedals, a wah will likely perform better when put after these pedals.

It's also common to put wah pedals after distortion-type pedals (including overdrive and fuzz) to get a fatter tone. However, putting the wah before the distortion may allow for increased wah reactivity and more harmonic content in the high-end.

Wah pedals generally sound better when put before modulation and time-based effects.

That all being said, experiment with the position of your wah pedal within the pedal chain to find the best spot for your rig.

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other EQ Modulation Effects

Now that we understand wah pedals, let’s have a look at other effects that utilize variations in a signal's frequency response:

• Envelope Filters Pedals
• Phaser Pedals

Note that any effect that alters the signal's tone will have some effect on the frequency response. That's in the nature of changing any audio signal in any way.

Modulation effects (chorus, vibrato, flanger, etc.) are effects that effectively produce modulation in the frequency response of the output signal. However, they do not actually achieve the effect through EQ. Phasers are a special caveat to this, as we'll discuss in a moment.

Envelope Filters Pedals

Envelope filter pedals are commonly referred to as “auto-wah” pedals.

This is a dynamic EQ-type effect that alters the EQ of the signal relative to the amplitude of the signal.

A transient is produced when a note is played on a guitar, bass, or any other instrument. The harder/louder the note is played, the larger the transient.

The transient is a fast increase and decrease in amplitude (of a sound wave or audio signal) that contains much of the harmonic content and timbre of the sound/signal.

Here's an illustration of a waveform and its transient:

So as transients are produced in the signal, the envelope filter will trigger its EQ filtering. As the signal amplitude drops, the filter will move across the frequency spectrum back toward “rest position”.

The spectral glide (wah effect) caused by an envelope filter, then, is controlled via the envelope (of which the transient is a part) of the signal, hence the name.

The MXR M82 Bass Envelope is a great example of an envelope filter designed for bass guitar.

To learn more about envelope filter pedals, check out my article What Are Envelope Filter Effects Pedals & How Do They Work?

Phaser Pedals

You may be thinking to yourself, “but phaser is a phase-modulating effect”. Well, that's the category it fits into and indeed a phaser does modulate the phase of its signal. However, the way it achieves this effect is largely based on modulation EQ.

Phaser pedals produce their distinguished effect by modulating a series of all-pass filters. Yes, all-pass filters are filters that pass all frequencies and do not actually really filter anything. This seems strange, I know.

The way an all-pass filter works, at least in a phaser, is by splitting the input signal in two. It inverts the phase of one copy and sends the dry signal through a low-pass filter and the inverted signal through a high-pass filter (or vice versa).

The result is that all frequencies pass through, but the phase of these frequencies changes. Phasers string multiple all-pass filter “stages” together and modulate the cutoffs of the all-pass filters' HP and LP filters to produce their effect.

So then, technically speaking, phasers are EQ-modulation pedals, too.

The Electro-Harmonix Small Stone is a simple example of a phaser pedal.

For more in-depth information on phaser pedals, check out My New Microphone's article What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

Related Questions

Should I use the effects loop on my amp? Effects loops effectively put effects units/pedals between the preamp and power amp of the guitar amplifier. If you're running the amp's preamp clean, putting pedals before or after won't make a big difference. If, say, you're using a distortion channel with reverb, you may want to put certain pedal in the loop and other in front.

Do I need a compressor pedal? Compressor pedals help balance out the dynamic of our playing by reducing the dynamic range of the audio signal. They are by no means necessary, though they may help increase perceived loudness; add sustain; improve transients, and make the guitar or bass fit better in the mix.

Related article: What Are Compressor Pedals (Guitar/Bass) & How Do They Work?

The post What Are Wah-Wah Guitar Effects Pedals & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

Flanger is one of the most recognizable effects at a guitarist's disposal, thanks, in large part, to effects pedals. This “jet swoosh” effect has made its way onto countless records and is worth understanding!

What are flanger pedals, and how do they work? Flanger pedals are stompbox-style units that affect audio signals (mainly for guitar or bass) with flanger. Flanger is an effect that copies an input signal and continually shifts the phase of one copy to produce a sweeping comb-filtering effect on the output signal.

In this article, we’ll further our knowledge of the flanger effect and how flanger pedals work. We'll also discuss modulation more generally. I’ll share a few flanger pedals throughout the article and offer some tips on how to get the most out of your flanger pedal(s).

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

Table Of Contents

• What Is The Flanger Effect?
• What Are Flanger Pedals & How Do They Work?
• Flanger Pedal Parameter Controls
• Tips On Using A Flanger Pedal
• Where Should Flanger Pedals Go In The Signal Chain?
• Other Phase-Shifting Effects
• Related Questions

What Is The Flanger Effect?

The flanger effect is defined as a phase-shift modulation effect that produces a sweeping comb filter across a signal's frequency response.

As an audio effect, flanging is often described as sounding like a “jet plane swoosh” or “drainpipe”. It's a tough effect to describe, but once you've heard it and understood it, you'll be able to recognize it again without issue.

A flanger doesn't actually use EQ (equalization) to produce its modulated comb filter effect.

To learn more about actual EQ pedals, check out my article What Are EQ Pedals (Guitar/Bass) & How Do They Work?

Rather, it uses a phase-shifting (delay) circuit to phase-shift a copy of a signal. It then mixes the original and phase-shifted signals together, causing constructive and deconstructive interference that results in a comb filter across the signal's frequency response.

The notches and peaks of the comb filter are modulated to produce the sweeper/whooshing effect of the flanger.

The term “flanger” is reminiscent of the effect's origin.

Flanging was first heard in the days of tape. A recorded track would be duplicated onto two different tapes on two tape machines.

Both machines would be played back in sync, and their playback head outputs would be mixed into a third tape machine that would record them.

Someone would then be tasked with lightly pressing their finger on the flange of one of the reels of one of the playback tape machines. This would slow the speed of one reel, continuously shifting its phase against the untouched reel of the other machine.

This small but gradual shift in phase would cause the comb filtering effect known as flanger.

Of course, after the person would remove their finger from the flange, the two tape machines would be out of sync. Pressing a finger on the second machine could bring them back into sync while producing more flanging (this time sweeping in the opposite direction).

So by pressing on the flange of two in-sync tape machines, we could (and still can) produce the flanger effect, hence its name. Today, it's easier to do it with electronic hardware or software.

Whether analog or digital, flanger circuits will sweep their flanging effect upward and downward in a repeating motion (until they're turned off).

Flanging effects units, including pedals, have additional controls, including resonance, width, and rate controls.

Let's now dive deeper into flanger pedals and discuss how they work.

What Are Flanger Pedals & How Do They Work?

Flanger pedals are stompbox-style units designed to receive guitar, bass or other instrument signals. Their circuits are designed to modulate the phase of the signal and produce the sweeping effect known as flanger.

The basic flanger design has two paths for the input signal to follow:

• A dry/direct path that leaves the signal unaffected.
• A delay circuit path that phase-shifts the signal which is modulated by an LFO (low-frequency oscillator). The output of the phase-shifting path can be fed back into its input.

The two signals are then summed together at the output mixer to produce the flanging effect.

Modulating the delay time of the delay circuit will cause a continuous phase shift between the dry and effect signals. This causes the sweeping comb filter in the output (once the two signals are mixed together).

To really understand flanging, though, let's back-track and begin by understanding phase.

What Is Phase?

Phase applies to waveforms. In particular, it is the location of a point within a wave cycle of a repetitive waveform.

A repetitive wave will go through 360º as it completes one period (one cycle). At this point, we can call the phase 360º or 0º.

Let's have a look at a simple sinusoidal wave with its phase degrees and period marked:

So we see that, with a simple sine wave (which has only one frequency), we have the 0º phase as at wave passes zero amplitude on its way upward; 90º is passed at the positive peak; 180º is the point at which the wave passes across the zero line on its way down; 270º is at the negative peak (trough), and 360º/0º is where we cross zero again on the way up and start the pattern over again.

As we can see, phase is closely related to time in sound waves. Recorded audio waves also have phase closely related to time, particularly during playback.

Of course, audio signals (including those from our guitars and bass guitars) are made of many different frequencies. The simple sine wave is just an easy way of illustrating phase.

Now that we know what phase is, we can look at phase shift. Phase shift is the key mechanic in the flanger effect.

Just as we can define a point within a period of a repeating waveform with phase, we can also define the phase shift between two identical waveforms with phase. Let's look at a few examples:

Here is an illustration of two sine waves with a 90º phase shift:

As the red wave reaches 90º through its period, the blue wave is at 0º of its cycle.

Here is an illustration of two sine waves with a 180º phase shift:

As the red wave reaches 180º through its period, the blue wave is at 0º of its cycle. At this phase shift, the two signals are said to be completely out of phase with one another.

If we were to sum these two waves, we'd have no output. The positive peaks of one wave would cancel the negative peaks of the other and vice versa.

Phase Shifting & Time

Let's now turn our sights toward the relationship between phase and time to further our understanding of phase and phase shifting.

A full period of a sine wave is considered to be one cycle and 360º. The time it takes for the wave to complete one cycle is dependent on the wave's frequency.

Let's take a 1 kHz (kiloHertz) sine wave as an example. 1 Hertz means one cycle per second. A 1 kHz sine wave, then, has 1,000 cycles per second with 1 cycle/period taking up 1 ms (millisecond) of time.

Now let's look at delaying the signal by 1 ms. This would result in a 360º phase-shift, and the shifted signal would be 100% in-phase with the original:

What would happen if we delayed a 500 Hz sine wave by 1 ms? A 500 Hz sine wave has 500 cycles per second, so each cycle would take 2 ms. Delaying the signal by 1 ms would delay it by half its wavelength (180º phase shift), which would put the signals 100% out-of-phase with each other:

The above two instances are the extremes (100% in-phase or out-of-phase). As we approach a 0º phase-shift, two signals become more in-phase. As we approach a 180º phase shift, two signals become more out-of-phase. 90º (along with 270º) is the mid-way way. This is important information to know when learning about flangers.

What if we doubled our 1 kHz frequency rather than halving it? A 2 kHz sine wave has 2,000 cycles per second or one cycle every 0.5 ms. Delaying a 2 kHz signal by 1 ms would put it 100% in-phase with the original.

There's a frequency between 1 and 2 kHz that, when delayed by 1 ms, will become 100% out-of-phase with the original. That frequency is 1.5 kHz, which has a period of 0.666 ms:

To generalize, we have the following equations to represent the 100% in-phase and 100% out-of-phase frequencies of a given sine wave.

\omega=360\frac{t}{p}

where:
ω = phase shift (in degrees)
t = time difference between the original and shifted signal (in seconds)
p = period of the wave being shifted (in seconds)

Remember that if the ω = 360x (x is any integer number), the shifted signal will be 100% in phase.

It the ω = 360x + 180 (x is any integer number), then the shifted signal will be 100% out-of-phase.

To keep with our example of a 1 ms delay/phase-shift, our in-phase frequencies would be:

• 1 kHz
• 2 kHz
• 3 kHz
• 4 kHz
• 5 kHz, and so on

Our out-of-phase frequencies would be:

• 500 Hz
• 1.5 kHz
• 2.5 kHz
• 3.5 kHz
• 4.5 kHz, and so on

This kind of phase filtering produces what is known as a comb filter. A comb filter is named after its comb-like appearance in a frequency response graph or EQ. A comb filter caused by the aforementioned 1 ms delay can be visualized across the entire frequency spectrum in the illustration below:

Note that, as the frequencies get lower, the period increases. A wave with a longer period is less affected, in terms of phase, by a given phase shift than a wave with a shorter period.

When a signal is mixed in with a phase-shifted version of itself, regularly spaced notches are created along its frequency response. This is the basis of flanging.

Note that the notches seem like they're getting closer and closer as the frequency increases. That's because the frequency scale is logarithmic by nature.

The Design Of A Flanger Pedal

So how are flangers pedals built to produce their effect?

Analog flanger pedals are designed, essentially, as delay pedals with a low-frequency oscillator (LFO) that modulates the delay time of the delay (phase-shifting) circuit.

So while a simplified diagram of an analog delay pedal would look like this:

Here’s an over-simplified signal diagram of a flanger pedal:

The delay circuit effectively shifts the phase of one signal relative to the other to produce the aforementioned comb-filtering effect. To achieve proper comb-filtering, a flanger delay should be kept below 20 ms at the upper range.

To learn about delay pedals, check out my article What Are Delay Pedals (Guitar Effects) & How Do They Work?

As an aside, the chorus effect, which is very similar design-wise to flanger, uses longer delay times.

So we know how the flanger circuit produces the all-important comb filter. However, just having a comb filter would be pretty boring. In fact, it would be like having a bad EQ applied to the signal.

In order to achieve flanging, the comb filter must sweep across the frequency spectrum. This movement is made possible with an LFO (low-frequency oscillator) connected to the delay circuit.

A low-frequency oscillator, as the name suggests, is an oscillator waveform with a low frequency. Generally, an LFO is described as being below 20 Hz. The best flanger sounds typically happen well below 20 Hz and even below 1 Hz (1 cycle per second).

A flanger LFO is generally a simple continuous waveform like a sine or triangle wave.

The LFO will be set to modulate the delay time of the delay circuit. As the delay time is altered, the phase shift between the direct and delayed signal changes. This, in turn, causes the sweeping motion of the resulting comb filter, back and forth across the flanger's frequency response.

As another aside, vibrato and chorus pedals use the same phase-shifting LFO setup to alter pitch and detune their signals. Flangers do the same. However, flanging is often modulated slower than chorus and vibrato, making the pitch-shifting/detuning less pronounced.

So to clarify, the amplitude of the LFO will control the range of delay times and, therefore, the modulation of the phase-shift and the shape of the comb filter. The frequency of the LFO will determine the rate/speed at which the delay time and phase-shift are modulated and, therefore, the speed/rate at which the resulting comb filter will sweep.

To push the intensity of the flanger, a feedback loop is provided for the delay circuit.

We can feed some adjustable amount (amplitude) of the phase-shifted signal back into the phase-shifting circuit with the feedback control.

What does this accomplish? Well, increasing the feedback within the phase-shifting circuit directly affects the resonances of the resulting comb filter. Increasing the feedback will make both the phase-cancelling notches and phase-cohesive peaks more prominent in the output signal.

Note that the mix/blend of the two signals also has an effect on flanger intensity, though it mostly softens the notches. A feedback loop will actually make the filtering more resonant.

Let’s have another look at the aforementioned 1 ms phase-shifted frequency response that did not have any feedback (red line) and compare it to the same circuit with some amount of feedback (blue line).

Like any feedback circuit, too much can produce undesirable run-away effects. Keeping the feedback/resonance control at a safe amount is essential.

And so that's how a flanger pedal works without getting into the nitty-gritty of electrical schematics.

Flanger Pedal Parameter Controls

Flanger is perhaps the most versatile modulation effect. We can get chorus sounds out of a flanger pedal, and flanger pedals will often offer chorus, vibrato, and perhaps even a few other effects.

To help us understand the full extent of a flanger pedal, let's have a look at the common controls we'll have:

• Speed/Rate
• Depth
• Delay Time
• Resonance
• Feedback
• Width
• Manual
• Mix

Speed/Rate

The speed/rate control of a flanger pedal controls the frequency of the LFO and, therefore, the speed of the flanger.

Slower rates are usually better when it comes to flangers, though faster speeds can also be used to great effect.

Depth

The depth control of a flanger pedal controls the amplitude of the LFO and, therefore, the overall frequency range of the sweeping comb filter.

The Electro-Harmonix Stereo Electric Mistress offers a rate control along with a flanger depth control. As we can see, this pedal is a two-in-one flanger/chorus.

Delay Time

The delay time control will either do the same thing as the depth control, or it will set the base delay time for the flanger (which the LFO will modulate about). Remember that, for flanging, it's best to keep the delay times short.

Width

The width control of a flanger pedal is the same thing as the depth control. It controls how wide the sweep of the flanging effect will be.

Manual

The manual control of a flanger pedal will control the base delay time of the phase-shifting circuit and, therefore, the centre point for the comb filter to sweep about.

The Boss BF-3 offers all the controls we've discussed thus far, along with a resonance control, which we'll get to shortly.

Feedback

The feedback control of a flanger pedal affects the level of signal that is fed back into the phase-shifting circuit. As we've mentioned, adding more feedback to the flanger will cause an increase in the resonances of the comb filter and, therefore, the overall intensity of the effect.

Feedback is sometimes labelled as “regeneration or “regen”.

The MXR M117R Flanger labels its feedback control as regen:

Resonance

The resonance control of a flanger pedal also controls the amount of feedback the phase-shiting circuit receives, thereby affecting the resonances of the peaks and notches in the comb filter.

The Source Audio SA240 Mercury Flanger offers depth, speed, resonance and delay (manual) controls.

Mix

The mix/blend control of a flanger pedal controls the amount of the phase-shifted signal that is combined with the dry signal at the output.

If a flanger pedal doesn't have a mix control, the wet/dry blend is typically 50/50, where the most phase cancellation will take place.

Tips On Using A Flanger Pedal

Here are a few points to consider to help you get the most out of your flanger pedal.

• Give it a break
• Keep the signal coming
• Try the stereo output if possible
• Get a chorus effect out of it

Give It A Break

Flanger is a very identifiable effect and can be very attention-grabbing in the context of a mix. Try giving the flanger pedal a break and only use it when it's musically appropriate.

This may be counter-intuitive in getting “more” out of your flanger pedal. However, using it sparingly will really make the effect pop out when it comes time.

Keep The Signal Coming

Flanger modulation is awesome. Like any noticeable modulation, having a consistent reference signal will really allow us to hear the entirety of the sweeping sonic movement.

Even when playing busier riffs, try to keep a decent amount of signal (either by sustaining or playing more percussively) to hear the entire flanger sweep with greater detail.

Try The Stereo Output If Possible

If your flanger pedal has a stereo out, try using it to achieve a wider and wilder effect.

The stereo output will have one output phase-inverted relative to the other, producing an almost super-modulated stereo sound.

Try going stereo in the practice room, studio, or live stage by plugging into two hard-panned inputs or two separate amps.

Get A Chorus Effect Out Of It

Many flangers can double as a chorus effect.

Try it for yourself by ridding of any feedback and increasing the delay time.

Where Should Flanger Pedals Go In The Signal Chain?

Flanger pedals, like most modulation-type effects pedals, work best after the dynamic, pitch-shifting, synth, and gain-based effects and before the time-based effects (delay and reverb).

This often puts them near the end of the pedal chain, mixed in with phasers, choruses, vibrato, uni-vibes, and the like.

Of course, this is just a suggestion. Try out different positions and listen for what sounds best to you when setting up the signal flow of your pedalboard!

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other Phase-Shifting Effects

Now that we understand flanger pedals, let’s have a look at other effects that utilize phase-shifting:

• Chorus
• Phaser
• Vibrato

Note that delay, doubling, Haas effect, and more could be considered phase-shifting effects as well. This is because they use a delayed copy of the direct audio. Any delay could be considered a phase shift (though it could also be thought of as delay or, in the case of mixing, multiple tracks).

Chorus

Chorus is very similar to flanger. In fact, it can be thought of, design-wise, as a flanger without feedback and with longer delay times.

The effect of a chorus is to add another voice to the signal that is slightly out-of-tune. Chorus units achieve this by altering the phase-shift (and, therefore, the pitch) of the “copied” signal and summing the dry and wet signals together at the output.

The result is a widening and thickening of the sound, similar to a chorus (multiple people) singing the same note, hence the name).

The Boss CE-2W Waza Craft is an awesome chorus pedal.

To learn more about chorus pedals, check out my article What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work?

Phaser

The way a phaser works is a bit different than flanger and the other types of phase-shifting pedals mentioned here.

Rather than using (and modulating) a delay circuit, a phaser will utilize a series of all-pass filters to change the phase of certain frequencies in its wet signal. This signal will then be mixed back in with the dry/direct signal, and the phase cancellation will cause the peaks and valleys in the output signal’s frequency response.

The defined frequencies are modulated by an LFO. A feedback loop in the phase-shifting circuit allows for greater resonances in the output signal’s sweeping peaks and helps intensify the phaser's sound.

The Empress Effects Phaser is a superb digital phaser pedal.

For more information on phaser pedals, check out My New Microphone's article What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

Vibrato

A vibrato circuit is effectively a chorus circuit without any direct signal.

In other words, a vibrato circuit is effectively a flanger circuit without the direct signal or feedback loop.

Vibrato is an effect that produces pulsating variations in pitch, raising and lowering the pitch around the desired note. It typically has a more pronounced LFO (an LFO with greater amplitude) than other phase-shifting pedals in order to achieve the pitch-altering effect it is designed to achieve.

The TC Electronic Shaker is a great example of a vibrato pedal.

For more information on vibrato pedals, check out My New Microphone's article What Are Vibrato Guitar Effects Pedals & How Do They Work?

Related Questions

Can you run a bass through a guitar effects pedal? Guitar effects will typically work well with bass guitar signals and vice versa. Some pedals are designed specifically for a certain instrument but will still work with other instruments, though results may vary. The harmonic profiles or guitar and bass signals are similar enough not to cause significant issues in most pedals.

Related article: Do Guitar Effects Pedals Work With Bass Guitar?

Is it bad to plug a guitar into a bass amp? A guitar can plug into a bass amp without overloading it or causing damage in practically all cases. However, because bass amps are designed to amplify bass signals, which have less high-end frequency information, plugging a guitar into a bass amp may result in less treble than we'd want.

The post What Are Flanger Pedals (Guitar/Bass FX) & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

Chorus is perhaps the most popular of all the modulation effects in terms of guitar (and bass) pedals. A nice chorusing effect can make our instruments sound larger than they are and demand the listener's attention without being overly obnoxious.

What are chorus pedals, and how do they work? Chorus pedals are modulation effects units built into stompbox-style housing and are typically designed for guitar/bass. As an effect, chorus produces one (or more) copies of the input signal, modulates the phase of each copy, and outputs all voices to produce a widening/thickening of the sound.

In this article, we’ll further our comprehension of chorus pedals and how they affect guitar and bass guitar signals. We'll discuss modulation more generally; I’ll share a few chorus pedals throughout the article, and I'll offer some tips on how to get the most out of your chorus pedal(s).

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use
• Top 11 Best Chorus Pedals For Guitar & Bass

Table Of Contents

• What Is The Chorus Effect?
• What Are Chorus Pedals & How Do They Work?
• Chorus Pedal Parameter Controls
• Tips On Using A Chorus Pedal
• Where Should Chorus Pedals Go In The Signal Chain?
• Other Phase-Shifting Effects
• Related Questions

What Is The Chorus Effect?

Before we get into chorus pedals and their inner workings, let's discuss what the chorus effect is.

The chorus effect is named after the use of a chorus in music.

No, we're not talking about the catchy singalong section of a pop song.

Rather, we're defining chorus as a group of people singing or playing the same note in unison. Choruses are often found in choirs (along with other choruses singing harmonies) and sections of an orchestra.

The effect, in nature, happens because we're not completely perfect beings. When a group of people sings the same note, there will be slight variations in timing and pitch between each voice and within each voice.

Of course, this is a good thing! We're not robots or synthesizers, after all.

As the different voices produce the same note (with the inevitable variations mentioned above), they all converge and are perceived as one sound. A sound larger and wider than any one voice alone could be (even if the volume is the same).

Of course, no voice should be out of tune. A pleasant chorus effect has slight variations in pitch in the realm of cents rather than semitones. When done correctly, the effect will sound harmonically rich and shimmery and not “out-of-tune”.

To give one more acoustic example, the piano actually has its own chorus. Each key of a piano is attached to a hammer that strikes one or more strings. The higher keys of an acoustic piano strike 3 strings; the middle keys strike 2 strings, and the lower keys strike one string.

Though each string for a given note is tuned to the same note, there will be slight variations in pitch that cause a chorusing effect.

As an aside, the fact that the bass keys only have one string gives us a hint: chorus may be a poor choice for bass and sub-bass notes/frequencies. For the most part, this is true.

The chorus effect is such a powerful and useful technique that it has long been emulated via electronics. There are analog and digital chorus effects units that include software, rack units, and, of course, guitar/bass pedals, among other designs.

The chorus effect fits into the modulation effect category.

Chorus is a phase-shifting/modulation effect that utilizes a delay circuit to shift the phase of a signal and then combines the unaffected and delayed signals together.

Combining the modulated phase-shift signal with the dry signal causes the time-varying detuned effect known as chorus.

What Are Chorus Pedals & How Do They Work?

Chorus pedals are stompbox-style units designed to receive guitar, bass or other instrument signals at their inputs and electronically affect the signal to produce the phase-shifting chorus effect at their outputs.

These pedals work by having two paths for the input signal to travel:

• A dry/direct path that leaves the signal unaffected.
• A delay circuit path that phase-shifts the signal which is modulated by an LFO (low-frequency oscillator).

The two signals are then summed together at the output mixer to produce the chorus effect.

Modulating the delay time of the delay path will cause pitch variation in the signal. As the delay time is shortened, the waveform is slightly compressed, causing an increase in pitch/frequency. As the delay time is lengthened, the waveform is slightly stretched, causing a decrease in pitch/frequency.

The delayed signal only happens once, rather than repeating several times, giving a doubling (phase-shifting) effect rather than a delay effect.

As an aside, a vibrato pedal works the same way, except it doesn't output the dry signal.

Note that stereo choruses will have two outputs but will typically share the same chorus circuit. The output of the chorus circuit (wet signal) will be sent directly to the summing mixer of one output channel (typically the left channel). It will be sent through a phase inverter before reaching the summing mixer of the other channel (typically the right channel).

A stereo chorus pedal can be used in mono by simply connecting to the left/mono output.

Some choruses will have two LFOs act upon their chorus circuit. These are known as bi-mode choruses.

There are other chorus designs, but these are the basic (and indeed the building blocks for more involved chorus designs).

So a chorus pedal will effectively produce a copy of the signal; modulate the copy, and output a blend of the dry and wet signals.

The blending of the dry and modulated signal(s) produces the chorus effect electronically, just like it's the blending of multiple voices that produces the chorus effect in nature.

The Design Of A Chorus Effect Signal Path

So how are chorus pedals built to produce the chorus effect?

Analog chorus pedals are designed, essentially, as delay pedals with no feedback loop and a low-frequency oscillator (LFO) that modulates the delay time of the delay (phase-shifting) circuit.

So while a simplified diagram of an analog delay pedal would look like this:

A chorus circuit will do away with the delay portion's feedback loop so that the delayed signal is not repeated. To simplify the diagram above even further, we'd have:

Note that delay circuits are rather involved. Though beyond the scope of this article, it's worth learning how delay pedals and units work to develop an even deeper understanding of chorus and modulation effects in general.

To learn more about delay pedals, check out my article What Are Delay Pedals (Guitar Effects) & How Do They Work?

For this article, know that a delay circuit delays the affected signal relative to the original signal.

To illustrate the three basic types of chorus pedals mentioned above, I've added the following diagrams:

Here's an over-simplified signal diagram of a mono chorus pedal:

The Electro-Harmonix Bass Clone is a great example of a mono chorus pedal designed for bass guitar.

The Electro-Harmonix Bass Clone is featured in My New Microphone's Top 11 Best Chorus Pedals For Guitar & Bass.

Here's an over-simplified signal diagram of a stereo chorus pedal:

The Boss CE-2W Waza Craft is a popular example of a stereo chorus pedal. It has a mono input and a stereo output (output A and B). Note that, by only plugging into output A, we'd achieve a mono chorus effect.

The Boss CE-2W is also featured in My New Microphone's Top 11 Best Chorus Pedals For Guitar & Bass.

Here's an over-simplified signal diagram of a stereo bi-mode chorus pedal:

The Ibanez BC-9 (now discontinued) is one of the few pedal examples that uses a bi-mode (dual LFO) chorus circuit.

Some digital effects offer more than two voices. This multi-voice chorus effect is popular in synths and other dedicated chorus effects. Here's an over-simplified signal diagram of a stereo multi-voice chorus pedal:

The DigiTech XMC (now discontinued) is a rare example of a multi-voice chorus pedal.

We can tell that typical chorus pedals are made with a single delay circuit modulated by a single LFO with either mono or stereo output options. The fact that the rare examples of bi-mode and multi-voice pedals have been discontinued tells us that there really isn't a market for these more involved designs.

That's good for us. It keeps the price of the pedals down and makes them easier to explain in this article! I just wanted to show you a few different configurations to prime your mind before getting into the inner workings.

Chorus Modulation & The LFO

Now that we know the basic design philosophy of a chorus unit, let's look into how chorus pedals modulate their signals.

As we've discussed, the modulation of a chorus pedal is controlled by an LFO.

A low-frequency oscillator, as the name suggests, is a wave with a low frequency. LFOs have frequencies below the audible range (20 Hz).

The LFOs used in chorus pedals have adjustable frequencies typically between 0.1 Hz to 6 Hz and above. Their waveforms are generally either sines or triangles.

From the previous section, we know that the LFO will modulate the delay circuit of the chorus pedal. What exactly does it modulate? It modulates the delay time parameter of the delay.

As the name suggests, delay time refers to the amount of time the delay circuit will delay the signal. Delay times of chorus pedals tend to be in the 18-24 millisecond range.

As an aside, vibrato and flanger pedals, which also utilize time-modulated delay circuits, have much shorter delay times.

Why does the chorus effect require a modulated delay time? There are two reasons. Let's defer back to the natural chorus of two singers singing the same note to help explain.

The most obvious reason to modulate delay time is to change the amount of delay between the two voices. This happens naturally with a chorus of singers since each singer will not hit the same note at exactly the same time (remember the 18-24 ms range).

However, this modulation is less pronounced in the actual chorusing effect.

The second reason actually affects the sound of a chorus effect the most. This reason is that modulating delay time will modulate pitch.

If you're ever adjusted the delay time of a regular delay pedal as a signal was running through it to an amp, you would have heard a change in pitch.

This pitch-variation/detuning happens because, as the delay time is shortened, the delayed signal wave is experiencing a slight amount of time compression. This time compression shortens the waveform, thereby increasing the frequency (and pitch) of the waveform.

Conversely, as the delay time is being lengthened, the wave of the delayed signal is experiencing a slight amount of time expansion. This time stretching elongates the waveform, thereby decreasing the frequency (and pitch) of the waveform.

This can be thought of as a sort of electronically manipulated Doppler effect.

Note that dedicated “pitch-shifting” pedals use a different method to affect the signal's perceived pitch.

To learn more about pitch-shifting pedals, check out my article What Are Pitch-Shifting Guitar Pedals & How Do They Work?

Going back to the two singers, there will be slight variation/vibrato/detuning in their voices, even when singing a defined note.

By controlling the delay time with an LFO, we effectively turn the delay time knob up and down very quickly. To achieve a subtle chorus, the delay time typically oscillates in the range of 18-24 milliseconds. More intense chorusing effects can be achieved by varying the delay time beyond this range.

When the detuned modulated signal is combined with the direct signal, we get the chorus effect.

Increasing the frequency of the LFO will increase the speed of the chorusing effect. Increasing the amplitude of the LFO will increase the intensity of the chorus effect by increasing the amount of pitch/delay-time variation in the wet signal.

It's important to restate that the chorus effect is a phase-shifting effect (just like phaser, flanger, and vibrato). However, unlike the phaser and flanger, chorus doesn't produce the same comb-filtering effects in the frequency response.

This is because the phase-shifted copy and the original signal are rarely at the same frequency (due to the delay/pitch modulation). This minimizes phase cancellation while still technically utilizing the delay-based phase-shifting technique.

We'll discuss the other phase-shifting effects shortly.

For now, we'll wrap up this section on how a chorus pedal works to give us the chorus effect!

Note that digital chorus pedals utilize digital signal processing (DSP) to achieve the same outcome.

Chorus Pedal Parameter Controls

Speaking of the LFO parameters, let's get into each of the controls we'd typically find on a chorus pedal to help further our understanding of how these pedals work and how we can dial them in to achieve our desired results.

The typical parameters we'll find on a chorus pedal are as follows:

• Speed/Rate
• Depth/Intensity
• Mix
• Low-Cut Filter

Speed/Rate

The speed/rate control of a chorus pedal controls the frequency of the LFO and, therefore, the speed at which the pitch variation happens in the wet signal.

A slower rate will produce a more subtle chorus effect. Increasing the rate will increase the perceived detuning of the effect as the phase-shifting will become more intense.

Depth/Intensity

The depth/intensity control of a chorus pedal controls the amplitude of the LFO and, therefore, the range of delay times the delay circuit will oscillate between.

Increasing the depth will increase the amount of pitch variation (the difference in pitch above or below the original signal) that happens in the wet signal.

Mix

The mix control of a chorus pedal controls the wet signal level that is mixed into the dry signal at the pedal's output.

Low-Cut Filter

A low cut-filter will remove some amount of the low-end from the detuned, phase-shifted signal. Phase shifting in the low-end, especially in stereo, can lead to poor results.

If we recall our discussion on the piano, we'll remember that even acoustic instruments are designed to remove chorus from the low-end.

Tips On Using A Chorus Pedal

Here are a few points to consider to help you get the most out of your chorus pedal.

• Subtlety is often best
• Focus on playing chords
• Let the chords ring
• Use stereo outputs if available

Subtlety Is Often Best

Chorus is one of those effects that sounds awesome when used subtly but can get out of control pretty quickly as the effect is cranked up.

Though the controls of your chorus pedal can certainly be turned all the way up, chorus is often best heard with the controls turned to more moderate levels.

Of course, experiment with your pedal to hear what it sounds like maxed out. Just know that the tone generally won't be overly useful.

Focus On Playing Chords

Like other modulation effects, chorus can really shine when there's plenty of harmonic content in the signal. Chords afford us this harmonic richness.

Let The Chords Ring

Letting the chords (or notes) ring can also help put the listener's attention on the chorus effect. A busy guitar or bass part with lots of notes/chords in quick succession can take away from the chorusing effect.

That being said, perhaps a busy part ran through chorus is exactly what the music needs!

Use Stereo Outputs If Available

Many chorus pedals offer stereo outputs. Use them to widen/thicken the sound of your guitar/bass even further! The stereo outputs will typically invert the phase of one channel to really make the sound of the guitar stand out in the stereo image.

This is easier done in the studio. However, taking two amps on stage can allow us to tap into the stereo awesomeness of chorus!

Where Should Chorus Pedals Go In The Signal Chain?

Chorus pedals, like most modulation-type effects pedals, work best after the dynamic, pitch-shifting, synth and gain-based effects and before the time-based effects (delay and reverb).

This often puts them near the end of the pedal chain, mixed in with vibratos, flangers, phasers, uni-vibes, and the like.

Of course, this is just a suggestion. Try out different positions and listen for what sounds best to you when setting up the signal flow of your pedalboard!

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other Phase-Shifting Effects

Now that we understand chorus pedals, let’s have a look at other effects that utilize phase-shifting:

• Flanger
• Vibrato
• Phaser

Note that delay, doubling, Haas effect, and more could be considered phase-shifting effects as well. This is because they use a delayed copy of the direct audio. Any delay could be considered a phase shift (though it could also be thought of as delay or, in the case of mixing, multiple tracks).

Flanger

Flanger works very similarly to chorus.

It produces a copy of the input signal (only one copy) and sends it through a delay circuit with an LFO-modulated delay time.

The flanger utilizes shorter delay times, resulting in a comb-filtering effect when the wet and dry signals are combined.

A flanger will utilize a feedback path to re-feed the delay circuit input. This increases the resonances of the comb filter.

The well-defined peaks and troughs of the comb filter are then modulated via the LFO that controls the variation of the delay time.

With all that, we have the classic sound of the flanger!

The Source Audio SA240 Mercury Flanger is an awesome flanger pedal with all the basic controls we need.

The Source Audio Mercury Flanger is featured in My New Microphone's Top 11 Best Flanger Pedals For Guitar & Bass.

For more information on flanger pedals, check out My New Microphone's article What Are Flanger Pedals (Guitar/Bass FX) & How Do They Work?

Vibrato

A vibrato circuit is effectively a chorus circuit without any direct signal.

Vibrato is an effect that produces pulsating variations in pitch, raising and lowering the pitch around the desired note.

The input of a vibrato pedal is not copied. Rather, the entire signal is sent through a delay circuit that has its delay time modulated by an LFO.

The TC Electronic Shaker is a great vibrato pedal with the typical controls and a tone knob.

The TC Electronic Shaker is featured in My New Microphone's Top 8 Best Vibrato Pedals For Guitar & Bass.

For more information on vibrato pedals, check out My New Microphone's article What Are Vibrato Guitar Effects Pedals & How Do They Work?

Phaser

The way a phaser works is a bit different than the other types of phase-shifting pedals mentioned here.

Rather than using (and modulating) a delay circuit, a phaser will utilize a series of all-pass filters to change the phase of certain frequencies in its wet signal. This signal will then be mixed back in with the dry/direct signal, and the phase cancellation will cause the peaks and valleys in the output signal's frequency response.

An LFO modulates the defined frequencies. A feedback loop in the phase-shifting circuit allows for greater resonances in the output signal's sweeping peaks and helps intensify the phaser's sound.

The Boss PH-3 Phase Shifter is an excellent example of a phaser pedal with all the typical controls.

The Boss PH-3 is featured in My New Microphone's Top 11 Best Phaser Pedals For Guitar & Bass.

For more information on phaser pedals, check out My New Microphone's article What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

Related Questions

Is it bad to plug a guitar into a bass amp? A guitar can plug into a bass amp without overloading it or causing damage in practically all cases. However, because bass amps are designed to amplify bass signals, which have less high-end frequency information, plugging a guitar into a bass amp may result in less treble than we'd want.

What effects do bass players use? Bass players, like guitarists, do not actually need pedals to sound great. However, common pedals and effects for bassists include:

• Tuner pedals (not an effect)
• Envelope filter pedals
• Compression pedals
• EQ pedals
• Boost pedals
• Overdrive pedals
• Distortion pedals
• Fuzz pedals
• Chorus pedals
• Synth pedals
• Looper pedals

Related article: Do Guitar Effects Pedals Work With Bass Guitar?

The post What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

Phaser is one of the most interesting audio effects in terms of its electronic design and effect on audio signals. Guitarists, bassists and other musicians can benefit greatly from a phaser pedal in their rig/pedalboard.

What are phaser pedals, and how do they work? Phaser pedals are stompbox units designed for guitar and/or bass. Phasers act to modulate the phase of select signal frequencies via a series of all-pass filters swept by an LFO. Phasers combine the direct and effected signals, which causes a series of sweeping peaks and troughs in the EQ.

In this article, we’ll deepen our knowledge of phaser pedals and how they affect guitar and bass guitar signals. We'll also discuss modulation more generally. I’ll share a few phaser pedals throughout the article and offer some tips on how to get the most out of your phaser pedal(s).

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

Table Of Contents

• What Is The Phaser Effect?
• What Are Phaser Pedals & How Do They Work?
• Phaser Pedal Parameter Controls
• Tips On Using A Phaser Pedal
• Where Should Phaser Pedals Go In The Signal Chain?
• Other Phase-Shifting Effects
• Related Questions

What Is The Phaser Effect?

The phaser effect is this cool, sweeping, modulated, filtering, trippy effect that sounds awesome on guitar, bass and pretty much any other instrument.

It's actually quite difficult to explain both as a sonic effect and as an electronic processor.

I've attempted to describe it sonically. Let's try electronically.

The effect achieved by a phaser is the sweeping modulation of a series of peak and notch filters in a signal's frequency response. Phasers produce a series of peaks and notches within a signal's EQ (frequency content), and they sweep these filters up and down within the audible frequency spectrum.

The number of peaks and valleys in a phaser circuit depends on the circuit. Some phasers allow us to adjust the number via the poles/stages control.

The width and rate of the sweeping effect are also adjustable.

We can also adjust both the resonance of the peaks and the attenuation of the notches to define the phaser sound further.

Adjusting these parameters will, of course, alter the sound of the phaser, making the phaser a versatile effect. That being said, the effect, when noticeable, is pretty identifiable as being “the phaser sound”.

Stereo phasers can take things a step further and have the same filtering motion in the left and right channels, only with one channel's modulation being a bit behind the other. Things can get really interesting here.

So, then, is a phaser a stereo equalizer? Well, no.

Perhaps, because it's a modulator (and sounds similar to a flanger), it could be based on a short phase-shifting delay circuit. Again, this isn't the case.

To produce their effect, phasers actually utilize a series of all-pass filters (which pass all frequencies and aren't really filters on the surface level).

The phaser effect is really cool, and I had to do my research for this article. I'm glad to be able to share what I've learned with you. Let's learn about phaser pedals and how they work!

What Are Phaser Pedals & How Do They Work?

Phaser pedals are stompbox-style units designed to receive guitar, bass or other instrument signals and produce the modulation-type phaser effect.

How they do so is rather interesting.

The MXR Phase 90 is one of the most popular phaser pedals ever to be produced and is ultra-simple with its single knob.

Before we get into how phaser pedals (and phaser units in general) work, let's define what phase is.

What Is Phase?

Phase applies to waveforms. In particular, it is the location of a point within a wave cycle of a repetitive waveform.

A repetitive wave will go through 360º as it completes one period (one cycle). At this point, we can call the phase 360º or 0º.

Let's have a look at a simple sinusoidal wave with its phase degrees and period marked:

So we see that, with a simple sine wave (which has only one frequency), we have the 0º phase as at wave passes zero amplitude on its way upward; 90º is passed at the positive peak; 180º is the point at which the wave passes across the zero line on its way down; 270º is at the negative peak (trough), and 360º/0º is where we cross zero again on the way up and start the pattern over again.

As we can see, phase is closely related to time in sound waves. Recorded audio waves also have phase closely related to time, particularly during playback.

Of course, audio signals (including those from our guitars and bass guitars) are made of many different frequencies. The simple sine wave is just an easy way of illustrating phase.

Now that we know what phase is, we can look at phase shift. Phase shift is the key mechanic in the phaser effect.

Just as we can define a point within a period of a repeating waveform with phase, we can also define the phase shift between two identical waveforms with phase. Let's look at a few examples:

Here is an illustration of two sine waves with a 90º phase shift:

As the red wave reaches 90º through its period, the blue wave is at 0º of its cycle.

Here is an illustration of two sine waves with a 180º phase shift:

As the red wave reaches 180º through its period, the blue wave is at 0º of its cycle. At this phase shift, the two signals are said to be completely out of phase with one another.

If we were to sum these two waves, we'd have no output. The positive peaks of one wave would cancel the negative peaks of the other and vice versa.

Phase Shifting & Time

Let's now turn our sights toward the relationship between phase and time to further our understanding of phase and phase shifting.

A full period of a sine wave is considered to be one cycle and 360º. The time it takes for the wave to complete one cycle is dependent on the wave's frequency.

Let's take a 1 kHz (kiloHertz) sine wave as an example. 1 Hertz means one cycle per second. A 1 kHz sine wave, then, has 1,000 cycles per second with 1 cycle/period taking up 1 ms (millisecond) of time.

Now let's look at delaying the signal by 1 ms. This would result in a 360º phase-shift, and the shifted signal would be 100% in-phase with the original:

What would happen if we delayed a 500 Hz sine wave by 1 ms? A 500 Hz sine wave has 500 cycles per second, so each cycle would take 2 ms. Delaying the signal by 1 ms would delay it by half its wavelength (180º phase shift), which would put the signals 100% out-of-phase with each other:

The above two instances are the extremes (100% in-phase or out-of-phase). As we approach a 0º phase-shift, two signals become more in-phase. As we approach a 180º phase shift, two signals become more out-of-phase. This is important information to know when learning about phasers.

What if we doubled our 1 kHz frequency rather than halving it? A 2 kHz sine wave has 2,000 cycles per second or one cycle every 0.5 ms. Delaying a 2 kHz signal by 1 ms would put it 100% in-phase with the original.

There's a frequency between 1 and 2 kHz that, when delayed by 1 ms, will become 100% out-of-phase with the original. That frequency is 1.5 kHz, which has a period of 0.666 ms:

To generalize, we have the following equations to represent the 100% in-phase and 100% out-of-phase frequencies of a given sine wave.

\omega=360\frac{t}{p}

where:
ω = phase shift (in degrees)
t = time difference between the original and shifted signal (in seconds)
p = period of the wave being shifted (in seconds)

Remember that if the ω = 360x (x is any integer number), the shifted signal will be 100% in phase.

It the ω = 360x + 180 (x is any integer number), then the shifted signal will be 100% out-of-phase.

To keep with our example of a 1 ms delay/phase-shift, our in-phase frequencies would be:

• 1 kHz
• 2 kHz
• 3 kHz
• 4 kHz
• 5 kHz, and so on

Our out-of-phase frequencies would be:

• 500 Hz
• 1.5 kHz
• 2.5 kHz
• 3.5 kHz
• 4.5 kHz, and so on

This kind of phase filtering can be visualized across the entire frequency spectrum in the illustration below:

Note that, as the frequencies get lower, the period increases. A wave with a longer period is less affected, in terms of phase, by a given phase shift than a wave with a shorter period.

In the picture above, we see what is referred to as a comb filter.

When a signal is mixed in with a phase-shifted version of itself, regularly spaced notches are created along its frequency response. These notches resemble a comb, hence the name.

Note that the notches seem like they're getting closer and closer as the frequency increases. That's because the frequency scale is logarithmic by nature.

The Way A Phaser Shifts Phase

Flangers and chorus circuits utilize delay to phase-shift copies of their original signal. In fact, a flanger simply modulates the comb filter we've discussed above. We'll get to these effects pedal types later in this article.

A phaser's frequency response is not a true comb filter with equally spaced peaks and valleys. Rather, the phaser defines the number of peaks and valleys in the frequency response.

It does so with phase shifting. However, it does it differently than simply delaying the signal.

As I mentioned earlier, the phaser utilizes a series of all-pass filters to achieve its phase-shifting. The phase-shifted signal must then be combined with the dry/direct signal to produce the phase cancellation required of the phaser effect.

What Is An All-Pass Filter?

On the surface, an all-pass filter seems silly. As its name suggests, it's a filter that allows all the frequencies to pass. That's not much of a filter then, right?

Well, rather than affecting the EQ of a signal as a regular filter would, an all-pass filter affects the phase of specific frequencies within the signal.

To learn more about EQ pedals, check out my article What Are EQ Pedals (Guitar/Bass) & How Do They Work?

An all-pass filter can be visualized in this simplified diagram:

The all-pass filter splits the input signal into two copies.

The copy is run through a phase inverter that puts it 180º or 100% out-of-phase with the original.

The copy is then sent through a high-pass filter while the original is sent through a low-pass filter (or vice versa). The signals are then summed together at the output.

The basic phase-shifting part of a phaser unit (with 4 poles/stages/all-pass filters) could look something like this:

At the low-end, the frequencies will have a 0º phase-shift compared to the original signal. At the high-end, the frequencies will have a 180º phase-shift compared to the original signal.

Frequencies in the middle will be attenuated by different amounts by either of the filters (though the sum of their amplitudes will be equal to the signal's original frequency response). This means that the middle frequencies will have some amount of phase-shift.

The frequency where the phase shift reaches 90º is equally affected by the high and low-pass filters and is known as the “corner frequency”.

The high-pass and low-pass filters are complementary and don't affect the overall frequency response whatsoever once the signals are summed back together.

So then, an all-pass filter allows all frequencies to pass through it but alters the phase of these frequencies.

A single all-pass filter (or “pole” or “stage” as it's often referred to in the context of a phaser) would produce a frequency-dependent phase shift that would look something like this:

So if we were to combine this signal with the dry signal (which is what a phaser does), we would have a sort of low-pass filtering effect. The original signal would be at 0º across its frequency response, and the phase-shifted signal would cancel it out more and more as the frequencies increased.

This result is certainly not conducive to the phaser effect.

To produce its effect properly, a phaser uses not one but a series of all-pass filters.

The Empress Effects Phaser is a digital phaser pedal that allows us to choose between 2, 4 or 3 stages.

Let's have a look at the frequency-dependent phase shifts that would happen as we add more all-pass filters (poles) in cascade:

Okay, so what do we have here? Let's begin with the 2-pole (sky blue) line.

When two all-pass filters are put inline, the phase shift will span from 0º to 360º. That's an entire period! In this case, the low and high end will be perfectly in phase with the original signal and will be heard clearly from the summing mixer.

The 2-pole phase shift passes 180º once, so there will be one notch in the output.

Let's skip the 3-pole line for a moment and focus on the 4-pole phase shift (orange) line.

This phase shift starts at 0º in the low end and ends up at 720º (in phase: 360 + 360 = 720) at the high end. It's also in phase somewhere in the mid-frequencies at 360º.

The 4-pole line crosses 180º and 540º, which means there will be two notches in the frequency response, and we sum the wet and dry signals together.

The 4-pole output would look something like this:

Going back to the 3-pole (pink) line, we see that we run into the same issue as the 1-pole set up with a low-pass filtering effect happening in the high frequencies as the phase-shifted signal approaches 540º (180º).

In order to utilize 3-pole designs, a phaser will run the wet signal through a phase-shift circuit before it reaches the all-pass filters. By shifting the phase, a 3-pole phaser design can achieve a fuller low and high-end (though not perfectly in-phase) along with 2 notches.

Here's an illustration of a 3-pole/3-stage frequency-dependent phase-shift plot with an initial phase offset.

Analog phaser units will generally offer 2 to 12 stages/poles and typically only even number options. Some phasers offer odd-number stages/poles.

Digital phasers can offer many more stages if need be.

A phaser with an even number (n) of stages generally has n/2 notches in the spectrum.

A phaser with an odd number of stages will generally have as many notches as the following even number.

Thus far, we've been under the assumption that the summing amp and output of the phaser would have a 50/50 mix of the direct signal and the phase-shifted signal.

At 50/50, the phaser effect would be the most prominent. This is due to the fact that the filtering effect is caused by phase cancellations between the dry and wet signals. Having too much of either will reduce the amount of cancellation, the depth of the notches and the sonic effect of the phaser.

The TC Electronic Helix has a depth knob to control the mix of the dry and wet signals.

The LFO & Modulation

So far, we've discussed how a phaser's phase-shifting circuit works and the effect that shifted signal has when it is summed together with the dry signal.

But this alteration in the output frequency response would be rather boring and typically wouldn't improve the perceived sound of the signal (think of it as a poorly setup EQ).

To get the phaser effect, we need the notches within the frequency response to move rather than stay stationary.

This is achieved via a variable resistor that affects the corner frequency of each all-pass filter by altering both the high and low-pass filters within the all-pass pole/stage.

Each stage is affected by the same variable resistor.

This variable resistor (potentiometer) is not controlled by a manual knob. Rather it's controlled with a low-frequency oscillator (LFO).

An LFO, as the name suggests, will oscillate at low frequencies. Typically this means below 20 Hz (the lower limit of the audible spectrum).

LFOs are typically a basic waveform. In the case of a phaser, they're often a sine wave or triangle wave.

As the LFO alters the pot's resistance, the corner frequency of each stage/pole is modulated upward and downward within the audible frequency spectrum. This, in turn, sweeps the peaks and notches of the frequency response up and down, creating the phaser effect!

Here is an updated version of the simplified phaser circuit knowing what we know now:

The frequency of the LFO determines the speed/rate of the sweeping effect of the phaser.

The Source Audio Lunar has a speed knob to control the frequency of its LFO and a shape knob to control its waveform.

The Feedback Loop & Phaser Resonance

To complete the phaser unit, we need a feedback loop in the circuitry.

Our completed (over-simplified) phaser diagram looks like this:

We can feed some adjustable amount (amplitude) of the phase-shifted signal back into the phase-shifting circuit with the feedback control.

What does this accomplish?

Well, what happens at the output when we mix the direct and the phase-shifted signal together? We get our phaser-effected signal with the expected number of peaks and valleys sweeping across the frequency response.

We can get a similar “affected” signal to go back into the phase-shifting circuit by combining the feedback signal with the original dry signal. This will produce deeper cuts in the notches of the phase-shifted signal and more noticeable resonances at the peaks of the signal.

This causes more pronounced resonances in the peaks of the output signal and a more distinct “phaser sound”.

Let's have another look at the aforementioned snapshot of a 4-pole phaser frequency response that did not have any feedback (orange line) and compare it to the same circuit with some amount of feedback (blue line).

Like any feedback circuit, too much can produce undesirable run-away effects. Keeping the feedback/resonance control at a safe amount is essential.

Like many other phaser pedals, the Boss PH-3 Phase Shifter has a resonance/feedback control (RES).

Note that the feedback loop is not delayed, and so the LFO will effectively modulate the dry and feedback signals to produce the same notches and peaks in the output signal.

Phaser Pedal Parameter Controls

Many different factors can control the performance of a phaser. Let's discuss the most important and common controls we'll have on a phaser pedal.

Common phaser pedal controls include:

• Speed/Rate
• Depth
• Feedback
• Resonance
• Width
• Stages/Poles
• Mix

Speed/Rate

The speed/rate controls the frequency of the LFO, which, in turn, controls the speed at which the comb-type filter will sweep across the signal's EQ.

A slower rate will be more subtle (with all else being equal).

Depth

Depth typically controls the intensity of the phaser effect.

The phaser effect is most prominent (with the deepest notches) when there is a 50/50 mix of the wet and dry signals, so depth could alter the mix.

It could also increase the amount of feedback within the all-pass cascade loop to increase the resonances of each peak in the phaser effect, thereby making the effect sound “deeper”.

Feedback

The knob labelled “feedback” will control the amount of the effected signal fed back through the phaser circuit. Increased feedback can get out of control. However, when done tastefully, we can increase the resonance of each peak within the comb filter and increase the intensity of the phaser.

Resonance

Resonance controls will simply increase or decrease feedback to affect the resonances of the output signal.

Width

Width controls increase or decrease the amplitude of the LFO and, thereby, increase the range of frequencies the phaser will affect.

Stages/Poles

The number of poles can be adjusted in some phasers. Remember that a phaser will produce 1 notch for every 2 poles. Increasing the number of poles will give a different, and arguably more obvious, phaser sound.

Mix

The mix, blend or amount controls the wet/dry mix of the direct signal and the effected signal.

Remember that the phaser is the most pronounced when the direct and phase-shifted signals are equally represented in the output mix. This is because the effect is based on phasing-out frequencies between two signals.

Read the manual to find out what the mix control actually means. It's often the case that having the control fully clockwise will get you to 50/50 (rather than having 50/50 be at 12 o'clock, as is the case in many other pedals.

Tips On Using A Phaser Pedal

Phaser pedals are a lot of fun to play through and tweak the controls. It's easy to get lost in the sound of a phaser, whether it's a new pedal or one that's been on your board for a while.

Here are just a few tips to help you get the most out of your phaser pedal:

• Give it a break
• Keep the signal coming
• Set the speed/rate to the rhythm of the song
• Try the stereo output if possible

Give It A Break

The phaser effect is awesome. We all know that.

However, having it on everything can get a bit tiresome for the listening after the third or fourth song.

This seems counter-intuitive, but you'll actually get more impact out of your phaser pedal if you reserve it for parts that could truly benefit from it. In other words, try not to overdo it or use your phaser simply for the sake of using your phaser!

Keep The Signal Coming

Phaser sounds awesome on long chords.

It can also sound really cool on more percussive-style playing. When throwing down some funkier chords, try hitting some muted strums between chord changes and listen to the phaser continuously modulate.

The point I'm making here is that if the phaser is steadily outputting some amount of signal, we'll be able to really tune our ear into the effect it's having.

Set The Speed/Rate To The Rhythm Of The Song

Try setting the speed or rate of the phaser to the song you're playing. This is made easier with digital phasers that have a tap tempo function.

Doing this can help to further lock in your playing the greater good of the song.

Try The Stereo Output If Possible

If the phaser has a stereo output and you have an extra guitar amplifier or preamp in your mixing console, try taking advantage of it.

Many stereo phasers will have two identical phasers modulated by a quadrature signal to put the left and right channel outputs a quarter-wave (90º) out-of-phase from one another.

This can yield an awesome phaser effect and take your tone to the next level!

Where Should Phaser Pedals Go In The Signal Chain?

Phaser pedals, like most modulation-type effects pedals, work best after the dynamic, pitch-shifting, synth and gain-based effects and before the time-based effects (delay and reverb).

This often puts them near the end of the pedal chain, mixed in with vibratos, flangers, choruses, uni-vibes, and the like.

Of course, this is just a suggestion. Try out different positions and listen for what sounds best to you when setting up the signal flow of your pedalboard!

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other Phase-Shifting Effects

Now that we understand phaser pedals, let's have a look at other effects that utilize phase-shifting:

• Chorus
• Flanger
• Vibrato

Note that delay, doubling, Haas effect, and more could be considered phase-shifting effects as well. This is because they use a delayed copy of the direct audio. Any delay could be considered a phase shift (though it could also be thought of as delay or, in the case of mixing, multiple tracks).

For more information on delay pedals, check out my article What Are Delay Pedals (Guitar Effects) & How Do They Work?

Chorus

Chorus is a modulation effect that produces a copy (or multiple copies) of the input signal and delays the phase of each copy relative to the original.

This is done with delay circuits (yes, just like on a typical delay pedal).

The copied signal is sent through a delay circuit, and an LFO alters the delay time. Altering the delay time will also alter the pitch as the waveform gets slightly stretched (as the delay time is increased) or slightly compressed (as the delay time is decreased).

What we get is a sort of vibrato effect on the wet signal(s). Combining the phase-modulated copy/copies back with the dry signal produces the chorus effect.

Chorus produces a widening/thickening of the sound similar to if a chorus of people were singing the note (hence the name). Not everyone would be perfectly on pitch the entire time (in typical circumstances), and the chorus effect emulates this electronically.

The Hartke HC33 is a great example of a chorus pedal that sounds great on bass guitar.

To learn more about chorus pedals, check out My New Microphone's article What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work?

Flanger

Flanger works very similarly to chorus.

It produces a copy of the input signal (only one copy) and sends it through a delay circuit with an LFO-modulated delay time.

The flanger utilizes shorter delay times, resulting in a comb-filtering effect when the wet and dry signals are combined.

A flanger will utilize a feedback path to re-feed the delay circuit input. This increases the resonances of the comb filter.

The well-defined peaks and troughs of the comb filter are then modulated via the LFO that controls the variation of the delay time.

With all that, we have the classic sound of the flanger!

The TC Electronic Vortex is an awesome flanger pedal with all the basic controls we need.

For more information on flanger pedals, check out My New Microphone's article What Are Flanger Pedals (Guitar/Bass FX) & How Do They Work?

Vibrato

Vibrato is an effect that produces pulsating variations in pitch, raising and lowering the pitch around the desired note.

A vibrato circuit is effectively a chorus circuit without any direct signal.

The input of a vibrato pedal is not copied. Rather, the entire signal is sent through a delay circuit that has its delay time modulated by an LFO.

The TC Electronic Shaker is a great example of a vibrato pedal.

For more information on vibrato pedals, check out My New Microphone's article What Are Vibrato Guitar Effects Pedals & How Do They Work?

Related Questions

Can you use guitar effects pedals for bass? Effects pedals are often designed for guitar but will universally work with bass guitar as well so long as the connection is correct (typically a 1/4″ patch cable). Some pedals may have difficulty tracking the lower octave of the bass guitar, but all pedals can work with bass guitar.

Related article: Do Guitar Effects Pedals Work With Bass Guitar?

Where do fuzz pedals go in a pedal chain? Fuzz pedals typically work best at the very beginning of the pedal chain because they fundamentally alter the waveform of the guitar signal. Not only do fuzz pedals affect clean guitar/bass signals better than modulated/time-varied signals, but the pedals after the fuzz (modulation and time-based effects) will sound better as well with fuzz before them (rather than after).

Related article: Guitar Pedals: Boost Vs. Overdrive Vs. Distortion Vs. Fuzz

The post What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

Tremolo is an awesome effect that has the potential to really give a guitar or bass that extra character it deserves in a mix. This modulation/dynamic sort of hybrid effect can be easily accessed via a pedal.

What are tremolo guitar effects pedals, and how do they work? Tremolo pedals are stompbox units designed for guitar and/or bass (though they work with other electric instruments) that produce the amplitude-varying tremolo effect. Tremolo is a modulation effect that varies a signal's amplitude over time and is defined by the rate and depth of its modulation.

In this article, we’ll further our understanding of tremolo and tremolo pedals along with the other effects types that vary signal amplitude in one manner or another. I’ll share a few pedal examples along the way and tips on how to get more out of your tremolo pedals.

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

Table Of Contents

• What Is Tremolo?
• What Are Tremolo Pedals & How Do They Work?
• Tremolo Pedal Parameter Controls
• Tips On Using A Tremolo Pedal
• Where Should Tremolo Pedals Go In The Signal Chain?
• Other Amplitude Modulation Pedals
• Related Questions

What Is Tremolo?

Tremolo, in music, is broadly defined as a trembling effect. This effect is largely achieved through variations in the amplitude of a sound source.

This wide definition can be divided into two main types of tremolo, though both vary the amplitude rapidly.

The first type of tremolo is that of “rapid reiteration”. Think of tremolo picking (alternating upward and downward picking at a fast rate), for example.

The rapid reiteration style of tremolo achieves the effect thanks to the nature of transients. In the majority of cases, producing a note on an acoustic instrument, synthesizer or with our voice will produce transient information.

Transients are the high amplitude, short-duration peaks in the sound wave (or audio wave) at the beginning of a waveform. They hold much of the character of the sound source.

Rapidly playing a musical note will produce transients at a fast rate. Just as the transient of the wave falls, the next transient is produced. This yields a sort of tremolo (rapid amplitude varying) effect.

This isn't how tremolo pedals go about things. However, this type of effect is achievable by playing technique (tremolo picking, for example).

The second type of tremolo, which is how tremolo pedals are designed, is amplitude variation. Think of the vocal tremolo technique while a single, long note is being held.

This type of amplitude modulation tremolo can be relatively easy to produce as an audio effect.

Guitarists, I should go beyond the explanation above to state that tremolo is not vibrato and vibrato is not tremolo. Don’t let Fender fool you!

Vibrato is a rather fast modulation of a signal’s “pitch”. Tremolo, as we've discussed, is a rather fast modulation of a signal’s amplitude.

The “vibrato” effect built into some amplifiers (you, the one that varies the signal's amplitude) is really tremolo.

The “tremolo arm” (sometimes referred to as the whammy bar) that affects the guitar's pitch is really vibrato.

Labelling of tremolo and vibrato can become tricky in the world of guitar. It’s important, then, to not only know the true definitions of the two effects but also that you’ll likely run into improperly labelled units during your lifetime.

For more information on vibrato pedals, check out the following My New Microphone article:
• What Are Vibrato Guitar Effects Pedals & How Do They Work?

What Are Tremolo Pedals & How Do They Work?

Tremolo pedals are stompbox-style units designed to receive guitar, bass, or other instrument signals and produce a tremolo effect by rapidly altering the audio signal's amplitude.

These pedals work by effectively reducing the amplitude of the input signal and bringing it back up to unity at a very fast rate.

In terms of audio electronics, we can think of tremolo as turning the volume knob up and down very fast. The rate of a tremolo unit reflects the frequency at which we turn the volume up and down. The depth of a tremolo unit reflects the amount we turn the volume down before bringing it back up.

Tremolo pedals (and tremolo circuits within guitar amplifiers) are designed in one of two ways:

• Signal modulation tremolo (common)
• Bias modulation tremolo (rare)

Each of these methods utilizes an LFO (low-frequency oscillator) at the heart of the design.

Low-frequency oscillators, as their name suggests, oscillate at low frequencies. Typically this means below 20 Hz (the lower limit of the audible spectrum).

The speed/rate control of a tremolo pedal affects the frequency of the LFO. The amplitude of the LFO will control the amount/depth of the tremolo's attenuation of the guitar/bass/instrument audio signal.

A typical tremolo LFO frequency range is between 3 – 10 Hertz (cycles per second). The typical waveform of a tremolo LFO is a sine wave. Of course, these generalities are simply generalities and are not always the case.

Now that we know what an LFO is, let's move on to the two types of tremolo units.

Signal Modulation Tremolo

The signal modulation tremolo circuit uses its LFO to control an opto-isolator (aka optical assembly).

An opto-isolator is an electrical component with 4 legs: two for an internal lamp (yes, one that produces light) and two for a light-dependent resistor (LDR).

LDRs are interesting. They're typically made of cadmium sulphide or a similar photo-resistor placed inside an enclosure. A lens in the enclosure will allow light to reach the photo-resistive material.

When there's no light shining on the photo-resistor, its resistance is very high. When there is light shining on the photo-resistor, its resistance drops to very low levels.

The LFO, in this case, sends a varying voltage to the lamps of the opto-isolator. As the voltage varies, the brightness of the lamps varies. As the brightness of the lamps varies, the resistance of the LDR varies.

The LDR, then, is a variable resistor, which allows more or less voltage to pass through the tremolo circuit. Resistance and voltage have a linear inverse relationship. As resistance increases in a circuit, the voltage decreases and vice versa.

Since the analog audio signal amplitude is defined by voltage, this oscillating resistance causes an oscillating amplitude.

A second variable resistor is put in series after the LDR. This potentiometer is not controlled by an LFO, but it does work to increase or decrease the overall resistance of the circuit.

This potentiometer controls the intensity of the vibrato. By increasing the pot's resistance, we reduce the overall effect of the LDR on the signal and, therefore, reduce the intensity of the tremolo.

So a simplified diagram of a signal modulation tremolo would look something like this:

The frequency of the LFO controls the speed/rate of the vibrato. The amount of resistance of the potentiometer controls the intensity (with inverse proportionality).

The Electro-Harmonix Stereo Pulsar is a classic tremolo pedal that utilizes signal modulation to produce its effect. It also has a stereo output that, when utilized, outputs two different tremolo signals: one with the LFO in-phase and the other with the LFO out-of-phase.

Bias Modulation Tremolo

Bias modulation tremolo is far less common in both tremolo pedals and the tremolo circuits of guitar amplifiers.

In this design, the LFO varies the bias voltage going to a triode vacuum tube or output preamp. These tubes have been used and are still used as audio signal amplifiers. “Output preamps”, as I'll refer to them here, are typically n-channel JFETs (junction-gate field-effect transistors) that mimic the workings of a triode but are based on transistor technology.

Of course, we're not looking to amplify the input signal to drive a speaker. However, we can still use a tube/preamp to alter the signal's amplitude and cause tremolo.

Here's a simple illustration of a triode vacuum tube:

• A: anode
• G: grid
• K: cathode
• H: heater

Here's a simple illustration of a JFET:

• S: source
• G: gate
• D: drain

Though these are two very different devices, they work similarly. The tube's anode, cathode and grid are somewhat analogous to the JFET's source, drain and gate, respectively. This is not fully true, but it is a good way to envision how they serve the same purpose in a tremolo pedal.

The bias voltage is a DC voltage applied to the grid of a tube in order to set a baseline current through the tube (between the anode and cathode). The AC voltage of the input audio signal is then superimposed on the DC bias to control the “output” of the tube (between the anode and cathode).

By bringing the bias voltage down, we effectively drop the output voltage. Bringing the bias voltage back up will bring the output voltage us as well.

When heated and by itself, a tube will typically have a fixed bias and a steady output current. Applying an [often lower amplitude] AC audio signal at the gate will control this [often higher amplitude] output signal. That's essentially how a tube works as an amplifier.

However, if we're sending an audio signal to the gate and oscillating the bias voltage, we can “amplify” the audio signal while also producing the tremolo effect.

To cause the oscillation necessary for tremolo, there must be an RC network (basically a resistor and capacitor in series) between the grid (input) and anode (output) of the tube.

The LFO will control the resistance of the variable resistor, which will change the capacitor's charge time, which in turn changes the rate of the tremolo. More resistance means slower charging, which results in slower tremolo.

Another variable resistor (this time a potentiometer) is put between the RC network and the grid (in series). Increasing the resistance of this resistor reduces the intensity of the tremolo. Reducing the resistance increased intensity.

The basics of this circuit are very similar to the signal modulation circuit in that they both have a variable resistor for speed control followed by a potentiometer for intensity control.

Note that if the bias voltage is too negative, the tubes will cut off. Conversely, if the voltage is too positive, the tube may overheat and burn up in a relatively short amount of time.

The Origin Effects Revival TREM is a bias modulation tremolo pedal that utilizes discrete transistor-based (JFET) circuitry to replicate the tube sound. Its tube-amp style signal path is designed using all-analog components (only minus the tubes).

A Note On Digital Tremolo Pedals

Tremolo pedals can also be digital and have chips that emulate either of the methods discussed above.

Digital pedals that offer tremolo often offer it as an additional effect to other modulation-type effects. These pedals will typically have extra functionality over analog tremolo pedals such as clock syncing, tap tempo, and ratio/rhythm controls.

The Seymour Duncan Shape Shifter is an awesome example of a digital tremolo pedal.

Tremolo Pedal Parameter Controls

As we’ve discussed, tremolo is largely defined by the speed and depth of the amplitude oscillation. The speed is controlled by the frequency of the LFO, while an additional variable-resistance potentiometer controls the depth. Let’s look at these parameters along with the other controls we’ll commonly find on a tremolo pedal:

• Depth/Intensity
• Rate/Speed
• Shape
• Tap Tempo
• Ratio
• Level

Depth/Intensity

Depth/intensity refers to the amount of amplitude variation a tremolo will cause.

A deeper tremolo means a larger difference between the high and low signal amplitudes outputted by the pedal. The effect will be more noticeable.

A shallower tremolo will cause less variation in the output amplitude, and the effect will be more subtle.

Rate/Speed

The rate or speed control affects the rate at which the tremolo circuit will drop the amplitude and bring it back up again. It's defined by the frequency of the LFO and can be thought of as how many times the tremolo completes one cycle of amplitude variation per second.

Shape

Shape controls are available on some tremolo pedals. They will effectively alter the waveform of the LFO.

Typically a tremolo will work with a sine wave LFO. However, we can change the waveform to achieve different styles of tremolo. Other common basic LFO waveforms include the square, triangle and even the sawtooth wave.

Sometimes this control can be discrete, and other times it can be continuous. It may also be labelled as “slope”.

Tap Tempo

Tap tempo allows users to tap a footswitch in order to establish a set tempo for the tremolo effect.

Ratio

Ratio is very similar to speed/rate.

Using the set tempo, the ratio control will alter the speed of the LFO to match some subdivision of the tempo (quarter note, eighth note, dotted eighth note, triplet quarter note, etc.).

Level

The level parameter of a pedal controls the output level of the signal. Tremolo has a tendency to lower the natural transients of the guitar signal, so a bit of added level can be great to remove any perceived drop in loudness as the tremolo pedal is turned on.

Tips On Using A Tremolo Pedal

Here are a few points to consider to help you get the most out of your tremolo pedal.

• Subtlety is often best
• Max out the intensity and speed for an “underwater” effect
• Sync up the speed
• Play with the rhythm of tremolo in relation to a delay pedal
• Try a tremolo pedal after a reverb pedal

Subtlety Is Often Best

We may want to really show off our new tremolo pedal and the great effect it can have on our sound and tone. However, subtlety often yields the best results with tremolo. Try using slower rates and less intensity to find a sound that adds character without being overbearing.

Max Out The Intensity And Speed For An “Underwater” Effect

This is the opposite of the last tip. Cranking the controls on a tremolo pedal can yield an awesome “underwater” effect. Try it out for yourself!

Sync Up The Speed

This can be done rather easily with the digital tremolo pedals that offer tap tempo.

If you're using an analog pedal (or a digital pedal without a tempo control), take some time to learn the sound of the various speed/rate positions. Set these manually to match the tempo of the song.

Play With The Rhythm Of Tremolo In Relation To A Delay Pedal

Tremolo and delay together can yield very dynamic results. We can set it up so that some delay repeats are dropped in level compared to their successors rather than the typical gradual drop-off of repeats.

Try putting the tremolo before the delay in the pedal chain and vice versa. We can find lots of cool rhythmic patterns by combining delay and trem.

To learn more about delay pedals, check out my article What Are Delay Pedals (Guitar Effects) & How Do They Work?

Try A Tremolo Pedal After A Reverb Pedal

Some guitar amplifiers have tremolo circuits built into their design (sometimes mislabelled as “vibrato”, as we've touched on earlier in the article). These circuits are often put after the reverb circuit (if the amp has both).

We can emulate that effect by putting a vibrato pedal after a reverb pedal in our pedal chain.

To learn more about reverb pedals, check out my article What Are Reverb Pedals (Guitar Effects) & How Do They Work?

Where Should Tremolo Pedals Go In The Signal Chain?

Tremolo is an amplitude modulation effect and will likely perform best among other modulation-type effects. That is, after dynamic, pitch-shifting, synth and gain-based effects.

Alternatively, try adding tremolo after time-based effects (reverb and delay). Some guitar amps that offer tremolo have it after their reverb, which can sound really nice.

Of course, these are just suggestions; take some time to experiment and listen for what sounds best to you when setting up the order of the pedals in your rig!

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

Other Amplitude Modulation Pedals

Before we wrap up the article, I'd like to discuss a few other effects pedals that work by affecting the amplitude of the signal.

More specifically, let's go over the following pedals that alter signal amplitude:

• Volume Pedals
• Ring Modulation Pedals

Volume Pedals

Volume pedals are generally designed as expression pedals (with treadle-type foot controller). They control to volume or amplitude of the signal passing through their circuit.

This volume control is achieved by means of attenuation rather than by applying gain.

Volume pedals are easy to understand. Depending on how the pedal is set up, the expression pedal will allow maximum signal in either toe-down or heel-down position and no signal at the opposite position.

Volume pedals do not only allow for muting, which is great between songs, while tuning, etc. They also allow for volume swells and other changes in dynamics due, in large part, to their continuously variable nature.

The Ernie Ball VP JR. is a popular volume pedal with a relatively small footprint (hence the name “Jr.”). This expression pedal will effectively control the volume of the guitar or bass signal.

Ring Modulation Pedals

Ring modulation is a bit more tricky to understand. Let me break down the effect in relation to tremolo.

I like to think of it this way: ring modulation is to tremolo what frequency modulation synthesis is to vibrato. It's not a perfect analogy, but it works for me.

So with tremolo, we have an LFO that modulates the amplitude of the signal. Ring modulation is a similar kind of amplitude modulation effect, only with faster oscillation.

What happens when we speed up the oscillation of a signal’s “tremolo”?

Eventually, as we increase the oscillator into the audible range, there will be less of a noticeable tremolo effect and more of an effect on the signal's waveform.

At this point, the modulator signal (what would be the LFO) begins to shape the carrier signal (the audio) into a new waveform with different harmonic content.

Ring modulation effectively summed the carrier and modulator signals together to create two brand new frequencies: the sum and difference of the two signals. The modulator wave is typically a simple wave selected by the effects unit, while the carrier signal is the guitar/bass/audio signal at the input.

So with a ring modulation pedal, we have our input signal (the complex waveform from the guitar), and we have a modular signal (often a sine or square wave produced within the pedal).

The modulator signal acts to modulate the amplitude of the input signal. This results in a modulated signal consisting of the sidebands from the sum and difference frequencies (similar to how amplitude modulation works).

The Fairfield Circuitry Randy's Revenge is a great example of a ring modulator pedal. We can control the frequency of the modulator signal and its waveform (between a square and a sine wave).

This pedal also has a “hi” and “lo” switch, which makes it fitting for an article focused on tremolo. The high mode takes the modulator frequency into the audible range and causes a ring mod effect. The low mode puts the modulator frequency into LFO territory, and the pedal effectively becomes a tremolo unit!

To learn more about ring modulation pedals, check out My New Microphone's article What Are Ring Modulation Effects Pedals & How Do They Work?

Related Questions

What is the difference between tremolo and vibrato? Tremolo and vibrato are both time-varying modulation effects. The difference is that the tremolo effect modulates the amplitude (volume) of the signal, while the vibrato effect modulates the frequency (pitch) of the signal. A “tremolo bar” on a guitar is confusing because it actually produces a vibrato effect.

What does a phaser pedal do? A phaser pedal is a stompbox unit that affects the input signal with a phaser circuit (analog or digital). The phaser effect utilizes an LFO to modulate multiple all-pass filters in series to sweep the phase of frequencies within the signal (or DSP that mimics this) to produce the phase-shifting effect known as phaser.

For more information on phaser pedals, check out My New Microphone's article What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

The post What Are Tremolo Guitar Effects Pedals & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.

Vibrato is an incredible technique for a guitarist, bassist, vocalist (and many other instrumentalists) to have in their arsenal. This natural technique can be achieved in both natural and unnatural ways via electronics in a vibrato pedal.

What are vibrato guitar effects pedals, and how do they work? Vibrato pedals are stompbox-style effects units designed mainly for guitar and bass that electrically (via analog and/or digital means) produce vibrato in the audio signal. Vibrato is an audible variation in pitch of a musical note over time, defined by the speed and depth of the variation.

In this article, we’ll further our understanding of vibrato and vibrato pedals along with the other effects types that utilize pitch-variation in one manner or another. I’ll share a few pedal examples along the way and tips on how to get more out of your vibrato pedals.

Related My New Microphone articles:
• The Ultimate Effects Pedal/Stompbox Buyer’s Guide
• Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use

Table Of Contents

• What Is Vibrato?
• What Are Vibrato Pedals & How Do They Work?
• Vibrato Pedal Parameter Controls
• Tips On Using A Vibrato Pedal
• Where Should Vibrato Pedals Go In The Signal Chain?
• A Note On Pitch-Shifting Pedals
• A Quick Discussion Of Frequency Modulation Synthesis
• Related Questions

What Is Vibrato?

Vibrato is a musical effect, often produced by vocalists and players of tuned instruments. The effect is that of regular pulsating variations in pitch, raising and lowering the pitch around the desired note.

Vibrato is used to give expression and character to melody lines and is largely determined by two factors:

• The amount of pitch variation, or “depth”.
• The speed at which the vibrato happens, or “rate”.

Singers can create vibrato via larynx control. String players can bend strings or bow the necks of their instrument (at the risk of going out of tuning or breaking something)! Brass and woodwind players can also achieve vibrato in various ways.

The above instances of vibrato are acoustic.

The vibrato effect can also be produced via electrical means. This is where vibrato pedals come into play.

I should note here that pitch is a subjective/perceptual property of sound (that translates into audio). The electronics (whether analog or digital) found in vibrato pedals, however, act objectively. This discrepancy is worth noting before we begin.

Musical pitch is a perceptual property of sound that allows listeners to qualify different sounds as higher or lower in musical notation. This auditory sensation allows us to relate the positions of different notes within the context of a musical melody.

Musical pitch and notation are related to frequency, though not entirely linked. The fundamental frequency (the lowest frequency of a note played by a tuned instrument) is generally the most linked to musical pitch.

A note with a higher fundamental frequency will be higher in pitch. A note with a lower fundamental frequency will be lower in pitch.

The exact note value of a given pitch (with its fundamental frequency) is largely determined by the tuning system used.

In western music, the two most common tuning systems are 12-tone equal temperament with A₄ = 440 Hz or A₄ = 432 Hz

I’ve written about the relationship between pitch and frequency in my article Fundamental Frequencies Of Musical Notes In A=432 & A=440 Hz if you’d like to check that out.

Guitarists, I should go beyond the explanation above to state that vibrato is not tremolo, and tremolo is not vibrato. Don't let Fender fool you!

Tremolo is a rather fast modulation of a signal's amplitude. As we've discussed, vibrato is a rather fast modulation of a signal's “pitch”.

The “vibrato” effect built into some amplifiers (the one that varies the signal's amplitude) is really tremolo.

The “tremolo arm” (sometimes referred to as the whammy bar) that affects the guitar's pitch is really vibrato.

Labelling of tremolo and vibrato can become tricky in the world of guitar. It's important, then, to not only know the true definitions of the two effects but also that you'll likely run into improperly labelled units during your lifetime.

To learn more about tremolo pedals, check out the following My New Microphone article:
• What Are Tremolo Guitar Effects Pedals & How Do They Work?

What Are Vibrato Pedals & How Do They Work?

Vibrato pedals are stompbox-style units designed to receive guitar, bass or other instrument signals and emulate the vibrato effect by altering the characteristics of the audio signal.

These pedals work by modulating the frequency content of the audio signal in order to affect the perceived pitch of the signal when it is transduced into sound.

It's important to note that, electrically speaking, vibrato pedals fit into the modulation category of pedals even though the audible effect is that of pitch-shifting. Pitch-shifting pedals are a bit different, as we'll discuss later in this article.

The vast majority of analog vibrato pedals are designed essentially as delay pedals with no dry signal at the output, no feedback loop, and a low-frequency oscillator (LFO) that modulates the delay time of the delay circuit.

So while a simplified diagram of an analog delay pedal would look like this:

A vibrato circuit will do away with the delay's feedback loop so that the delayed signal is not repeated.

…A simplified diagram of an analog vibrato pedal would look like this:

Of course, there's much more to an analog delay (and, therefore, an analog vibrato) pedal than this general overview, but this is a great starting point. Their bucket-brigade device delay chips and the signal conditioning circuits are worth knowing about.

To learn more about delay pedals, check out my article What Are Delay Pedals (Guitar Effects) & How Do They Work?

How does a delay circuit act to affect pitch and cause vibrato? If you've ever adjusted the delay time of an activated delay pedal, you've heard how a delay circuit can alter the pitch.

By modulating the delay time of a delay circuit, we can alter the perceived pitch of the audio signal. Think of this as a sort of electrical Doppler effect.

The amount of delay the input signal experiences in a vibrato pedal is modulated via a low-frequency oscillator (LFO). This causes variation in the wavelength and, therefore, frequency/harmonic content of the signal.

As the delay time slows down, the signal is effectively time-stretched, lowering its frequency content and dropping its pitch.

Conversely, as the delay time speeds up, the signal is effectively time-compressed, raising its frequency content and increasing its pitch.

Imagine modulating the delay speed back and forth very quickly but subtly. This is what an LFO does. Together, this system yields the vibrato effect!

Note that, in the system, there will be some amount of latency (actual delay) between the input signal and the output signal as the delay circuit processes the signal. Remember that the vibrato circuit is like a modulated delay without the dry signal.

Actually, if we dig a little deeper, we see that a vibrato circuit is actually a chorus circuit with a single copy and without a direct output.

Chorus pedals delay one or more copies of the direct signal and vary the delay times to produce one or more voices with slight vibrato. The voices are then mixed in with the dry/direct signal at the output.

Digital vibrato pedals emulate this same basic design with digital delay and DSP (digital signal processing).

Note that uni-vibe pedals, which offer chorus and vibrato settings, are actually multi-stage phaser pedals. However, they work with the same “vibrato = wet signal only” and “chorus = dry + wet signal” design.

To learn more about chorus pedals, check out my article What Are Chorus Pedals (Guitar/Bass FX) & How Do They Work?

Vibrato Pedal Parameter Controls

As we've discussed, vibrato is largely defined by the speed and depth of the pitch oscillation. Let's look at these parameters along with the other controls we'll commonly find on a vibrato pedal:

• Depth
• Speed/Rate
• Rise Time/Ramp
• Mode
• Tone

Depth

Depth is the amount of pitch changing the vibrato effect will produce.

In other words, it determines the extent to which the LFO will control the change in delay time within the delay circuit.

Speed/Rate

The speed or rate parameter controls the frequency of the LFO and, therefore, the speed of the perceived pitch alterations.

Rise Time/Ramp

Rise time or ramp controls the initial onset of the vibrato effect once the pedal is engaged by ramping up the level of the LFO.

Mode

Mode can mean a few things.

Most often, it refers to the functionality of the pedal's footswitch or, in other words, what the role of the footswitch will be for the pedal.

The Boss VB-2W Waza Craft has rate, depth, rise time, and mode controls. Its mode knob controls the functionality of the footswitch between latch, bypass and unlatch modes.

Latch mode means the pedal will be turned on with one click and bypassed with the next.

Unlatch mode means the pedal will be engaged when we step on the switch and bypassed as we step off.

Bypass mode is just like the latch mode except for one major difference: When the pedal is bypassed, the signal will bypass the analog BBD delay chip and only run through the pedals' buffered bypass circuit.

The EarthQuaker Devices Aqueduct Vibrato has rate and depth controls. Its mode control alters the shape of the LFO rather than the functionality of the footswitch.

Tone

Tone has little to do with the vibrato effect itself and instead activates either an EQ circuit, a boost, overdrive or distortion circuit, or some combination thereof.

The TC Electronic Shaker has the 4 controls mentioned above with the addition of a tone knob.

Tips On Using A Vibrato Pedal

Here are a few points to consider to help you get the most out of your vibrato pedal.

• Subtlety is often best
• Emulate tape warble
• Rise time can be your best friend
• Combine it with chorus and tremolo

Subtlety Is Often Best

Vibrato is one of those effects that can get pretty wild pretty quickly. Unless you're trying to make cartoon effects or something of the like, it's likely best to keep the settings low.

That being said, in the practice room, I definitely recommend cranking the knobs to hear what happens. Perhaps you'll find an awesome use for extreme vibrato!

Emulate Tape Warble

Combining vibrato with any type of lo-fi effect can yield some awesome effects. Keep the rate low and adjust the depth by ear.

Rise Time Can Be Your Best Friend

Natural vibrato is practically impossible to maintain consistently with acoustic instruments (including the voice).

Though we've largely become accustomed to the electronic vibrato effect, it can be to our benefit to make our vibrato pedals sound more “natural”.

Having a rise time will help us achieve this by offsetting the amount of vibrato the pedal will produce as we engage the pedal. This may require some clever pedal work (try using unlatched modes to get the most out of this technique).

Combine It With Tremolo

Combining vibrato with tremolo can add even more character to your sound by modulation both pitch and amplitude. Try it out for yourself with different rates between the two effects.

Where Should Vibrato Pedals Go In The Signal Chain?

Vibrato pedals, like most modulation-type effects pedals, work best after the dynamic, pitch-shifting, synth and gain-based effects and before the time-based effects (delay and reverb).

This often puts them near the end of the pedal chain, mixed in with phasers, flangers, choruses, uni-vibes, and the like.

Of course, this is just a suggestion. Try out different positions and listen for what sounds best to you when setting up the signal flow of your pedalboard!

To learn more about ordering pedals in the signal chain, check out my article How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide).

A Note On Pitch-Shifting Pedals

Although vibrato circuits have the effect of shifting the signal's pitch up and down, they are actually a type of modulation pedal at the core of their design.

Pitch-shifting pedals, which are all digital, actually sample the signal and move its frequency content to a new “note”.

Older analog “pitch-shifters” are limited to monophonic octave addition.

Let's now have a look at a few actual pitch-shifting pedal types:

• Pitch-bending
• Transposition
• Detune
• Octaves
• Harmonization
• Shimmer delay/reverb
• Synth-like

Pitch-Bending Effect

Pitch-bending pedals bring time into the equation and can gradually shift the pitch of a note from one pitch to another. This can be done via an envelope, as we’ll see with the Boss PS-6, or via an expression pedal, as we’ll see with the DigiTech Whammy 5.

The Boss PS-6 is a harmonizer pedal at its core with octave capabilities along with key control, interval settings (including triads) and minor or major modes. As we’d expect, the pedal also has a mix control to blend the direct and wet signals.

The DigiTech Whammy 5 is the modern version of the legendary Whammy pedal that started it all in terms of pitch-shifting guitar effects.

To learn more about pitch-shifting pedals, check out my article What Are Pitch-Shifting Guitar Pedals & How Do They Work?

Transposition Effect

Transposition-type pedals act to transpose your entire instrument up or down in pitch.

The best example of a “transposition pedal” is the DigiTech Drop.

Detune Effect

Detune is an interesting effect. It is an effect that is sometimes included in pitch-shifting pedals (like the aforementioned DigiTech Whammy 5 and Boss PS-6).

What detune does is it duplicates the signal (as any pitch-shifter does) and alters its pitch by cents of a semitone (rather than by specified intervals).

The result is a thickening of the signal and a sound similar to a chorus pedal.

The DigiTech Bass Whammy has a “shallow” and “deep” detune setting. The extent of the detune is controlled via the built-in expression pedal.

Octaves Effect

As the name suggests, octave pedals produce octaves above and/or below the determined pitch of the input signal.

The TC Electronic Sub ‘N’ Up can produce the following octaves in addition to the direct signal:

• 2 octaves below
• 1 octave below
• dry signal
• 1 octave above

Harmonization Effect

Harmonizer pedals allow for much more than simple octaves above or below the dry signal. These digital pedals will typically offer the choice of several intervals above and/or below the note(s) of the input signal.

The TC Electronic Quintessence is a perfect example of an intelligent and versatile harmonizer pedal with preset and user-defined keys, modes and harmonies to choose from.

Shimmer Delay/Reverb Effect

Shimmer effects can be thought of as a two-effects-in-one deal:

• Shimmer delay is like a delay with a direct out and a wet/delayed signal that is pitched up via a pitch-shifter.
• Shimmer reverb is like a reverb with a direct out and a wet/reverb signal that is pitched up via a pitch-shifter.

The Electro-Harmonix Canyon is a great example of a shimmer delay pedal, combining delay with pitch-shifting.

The Strymon BigSky is a great example of a digital delay pedal with tons of options.

It features the following emulations:

• Room
• Hall
• Plate
• Spring
• Swell (a different take on the bloom-type reverb)
• Bloom
• Cloud (a cathedral-type reverb)
• Chorale (a reverb combined with wah-like filtering)
• Shimmer
• Magneto (a reverb and delay effect emulating tape warble and echo)
• Nonlinear (a non-linear, unnatural and programmable reverb)
• Reflections (focuses on early reflections and sounds similar to a stereo delay)

For more information on delay and reverb pedals, check out the following My New Microphone articles respectively:
• What Are Delay Pedals (Guitar Effects) & How Do They Work?
• What Are Reverb Pedals (Guitar Effects) & How Do They Work?

Synth-Like Effect

True synth pedals are actually designed as synths with built-in oscillators that are controlled by an inputted guitar or bass signal.

However, some pedals are awarded the “synth” description if they simply sound like a synth. Pitch-shifting (particularly octave stacking) can turn a normal guitar signal into a synth-like audio signal. Combining that with other effects and filters can produce a sound that is more closely related to a synthesizer than a guitar.

The Electro-Harmonix POG2 is an example of such a pedal.

To learn more about synth pedals, check out my article What Are Synth Pedals (Guitar/Bass FX) & How Do They Work?

A Quick Discussion Of Frequency Modulation Synthesis

The vibrato effect modulates the frequency content of a signal with an LFO.

Low-frequency oscillators, as their name suggests, oscillate at low frequencies. Typically this means below 20 Hz (the lower limit of the audible spectrum).

What happens when we speed up the oscillation of a signal's “vibrato”?

Well, the pitch oscillations would get faster and faster until we could no longer discern that the pitch was varying. This happens when we pass from the LFO range into the audible range.

At this point, the modulator signal (what would be the LFO) begins to shape the carrier signal (the audio) into a new waveform with different harmonic content.

The modulator still modulates the frequency of the signal, but it alters the waveform rather than altering the perceived pitch.

This is the basis of frequency modulation, which, in the world of audio, is used in the following:

• FM synthesis to create synthesized waveforms (the carrier wave is modulated by a modulator wave, typically in the audible range of frequencies).
• FM radio transmission (where the carrier signal is in the very high frequency “VHF” band).

Here is a simple illustration of how frequency modulation works with sine waves:

Related Questions

What is the difference between tremolo and vibrato? Tremolo and vibrato are both time-varying modulation effects. The difference is that the tremolo effect modulates the amplitude (volume) of the signal, while the vibrato effect modulates the frequency (pitch) of the signal. A “tremolo bar” on a guitar is confusing because it actually produces a vibrato effect.

What does a phaser pedal do? A phaser pedal is a stompbox unit that affects the input signal with a phaser circuit (analog or digital). The phaser effect utilizes an LFO to modulate multiple all-pass filters in series to sweep the phase of frequencies within the signal (or DSP that mimics this) to produce the phase-shifting effect known as phaser.

For more information on phaser pedals, check out My New Microphone's article What Are Phaser Pedals (Guitar/Bass FX) & How Do They Work?

The post What Are Vibrato Guitar Effects Pedals & How Do They Work? first appeared on My New Microphone and is written by Arthur Fox.