What Are Reverb Pedals (Guitar Effects) & How Do They Work?


Reverb is one of the most popular effects for guitarists to have in a pedal. In fact, it’s one of the most common effects in music, period. We can find reverb units on pedalboards around the world.

What are reverb pedals and how do they work? Reverb pedals are [typically] digital and are designed to emulate the effects of reverberation. They affect the incoming guitar/instrument signal with pre-delay, decay and other parameters to mimic real acoustic reverb. The effected signal is then combined with the direct signal at the output.

In this article, we’ll discuss reverb pedals in much more detail, getting into each type of reverb; how reverb pedals work, and what they sound like. I’ll share a few pedal examples along the way and tips on how to get more out of your reverb pedal.


Table Of Contents


What Is The Reverb Effect?

Before we get into this article, let’s first discuss the reverb effect (in more words than the opening answer paragraph).

Reverb, as an audio effect, aims to recreate the effect of natural acoustic reverberation in an audio signal. As we’ll discuss shortly, reverb effects are achieved by different means, including springs, plates, analog BBD circuits, digital circuits, and the clever use of playback and microphones in physical space.

This reverb-effected signal is then often mixed back in with the original “dry” signal to give a greater sense of space to the overall audio signal.

Reverb, as an audio effect, sounds great on practically all sound sources because it’s rooted in the real natural world.

To really understand the reverb effect, which can be overly complicated when discussing digital signal processing, let’s look to comprehend reverberation as a natural occurrence in the world.

Reverberation, in acoustics and psychoacoustics, is defined as the persistence of sound in the environment after the sound has been produced by its source.

How does this happen?

Well, sound is made of mechanical waves that propagate through a medium. Most of the time, we humans will experience sound waves in air with frequencies between 20 Hz and 20,000 Hz.

These waves will travel outward from the source that created them. In an acoustic environment, these same waves will eventually reach a surface, at which point they’ll be partially absorbed by and partically refelected by the surface. The reflected waves will often hit another surface and perhaps even several more. This depends on the wave strength and the location and material of the surfaces.

Sound waves travel fast. The speed of sound is 343 m/s (1,125 ft/s) in air at 20 °C (68 °F). As we can imagine, in most diffuse-field environments, there will be plenty of reflections. Many of these reflections will come right back to our ear and are heard as reverb!

Reverb is often defined loosely by initial reflections that are heard within 50 milliseconds of the original source. This is in contrast to echoes, which are typically heard distinctly when more than 50 milliseconds after the original sound.

Eventually, and this typically happens rather quickly, the reflections will decay to zero amplitude and the reverb tail will have finished (assuming no more sound is coming from the source).

The reflections will not only lose acoustic power and amplitude as they travel through the medium but they will also be absorbed more and more by each surface they encounter.

Note that higher frequencies are more easily absorbed by surfaces and so reverb tends to be frequency-specific with the body (and tail) getting darker and darker as it approached zero.

Larger rooms/environments will typically have longer initial reflection times reverb decay times. Environments with surfaces that are more reflective will often have longer decay times, especially in the high-end.

Let’s have a look at an illustration of a reverberant sound to further our understanding:

Let’s quickly define the four distinct sections of the reverb effect:

  • Source: the sound that is being affected by the reverb. With pedals, this is typically the guitar/instrument signal.
  • Early reflections: the starting of the reverb effect that is typically delayed 1 – 50 milliseconds after the source signal.
  • Reverb body: the reverb effect when all the reflections/delayed signals interact with each other to produce the “reverb effect” This typically starts around 25 and will last as long as the decay time control allows it to.
  • Reverb tail: the reverb tail is defined as the end of the reverb once the effect drops 60 dB below the source signal level.

The reverb effect, in audio, aims to emulate this acoustic experience. Reverb, like delay, is a time-based acoustic reaction that has been co-opted into the realm of audio effects!

Related article: What Are Delay Pedals (Guitar Effects) & How Do They Work?

Of course, the rever audio effect can be manipulated much more than the natural acoustic reflections of the real world.

We’ll get to this later but the main four parameters of any reverb effect, which allow us to dial in and manipulate the effect, are as follows:

  • Effect level: the relative amplitude of the reverb-effected “wet” signal, often in relation to the dry/input signal.
  • Pre-delay: the amount of time between the initial signal and the beginning of the reverb-effectec signal. This mimics the initiall reflections of the real world environment.
  • Decay time: the length of time it takes for the reverb signal to reach zero amplitude relative to the time it began (at the pre-delay set point). This mimic the size and material of the real world environment.
  • Damping: the rate at which higher frequencies decay relative to the main decay time. This mimics the various reflective materials available in the real world environment

The reverb effect can be set to recreate space in the real world. It can also be used to give other-worldly and experimental effects that go beyond what any real-world environment could sound like.

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What Is A Reverb Pedal?

A reverb pedal, then, is an effects unit that produces audio reverb and is built in the form of a stompbox.

Reverb pedals are often used by guitarists and bassists as well as keyboardists and synth players.

Related articles:
Do Guitar Effects Pedals Work With Bass Guitar?
Do Guitar Pedals Work With Keyboards & Synthesizers?

Reverb pedals are incredibly popular and for good reason. Nearly every musician can benefit from a good reverb pedal. This is true whether it’s used subtly to add depth and space to signal; to create atmospheric cascading guitar tones, or anything in between. This is largely due to the fact that reverb is naturally occurring in acoustic environments everywhere.

Reverb pedals are nearly all digital. Digital signal processing (DSP) has allowed us to effectively emulate many different types of reverb. This is something that analog circuits struggle to do. Springs and plates could be used in pedals but are limited in functionality; large in size, and sound rather unnatural.

With DSP, however, any type of reverb can be emulated. Many reverb pedals will have multiple types of reverb that we can select between.

The market understands this and pretty well every pedal manufacturer has at least one reverb pedal in their product line.

Related article: Full List: Guitar Effects Pedal Brands/Manufacturers

To sum things up, a reverb pedal is a stompbox reverb unit. It is typically designed to be controlled by the player’s feet and will often have the common control parameters, including effect level, pre-delay, decay time and damping. Nearly all reverb pedals are digital and are programmed to emulate one or more types of reverb.

Related article: What Is A Guitar Effects Pedal And How Do Pedals Work?

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Types Of Reverb Effects

So far we’ve discussed reverb as a time-based audio effect that aims to recreate the sound of reverberation. Reverb pedals are reverb units that are designed into a stompbox format and are targeted at guitarists, bassists, synth players and other musicians.

With that basic understanding, we should look to the different methods used to achieve this reverb effect and the various types of reverb pedals we’ll encounter.

The main types of reverb are as follows:

Let’s discuss each to further our comprehension of reverb and reverb pedals.


Acoustic Emulation Reverb

Reverb, as an audio effect to be used in recordings, was originally created with actual reverberant spaces.

Specific rooms were chosen for various reverb sounds. This is the most basic form of reverb.

If producers needed reverb after-the-fact, a loudspeaker would be set up in an actual physical space to play back the sound. A microphone would be placed strategically to pick up the sound waves with reverb.

These physical spaces are often referred to as “echo chambers”. As I’ve listed above, the main categories of echo chambers (defined by typical size) are:

Room

Room reverb refers to the reverb of a small room. Think of a living room or a smaller live studio room (without extensive soundproofing to minimize reflections). This “type” of reverb aims to recreate the intimate sonic nature of being in a room.

Room reverb is defined largely by its fast and relatively loud early reflections (1 – 25 ms is typical) and its short decay times (500 – 800 ms is typical). The damping is typically high, which yields a warmer and darker sound.

1985 brought forth two of the first and only analog reverb pedals. These pedals were the DOD FX45 and the Arion SRV-1. Each pedal utilized bucket-brigade device (BBD) chips (the same analog circuits used in true analog delay pedals).

The DOD FX45 was an analog reverb pedal designed to emulate room reverb through a BBD circuit.

Chamber

Chamber reverb refers to the reverb of a chamber or large room. Think of a well-designed live room in a studio and the characteristic reverberation it produces.

Chamber reverb can be thought of as a larger and more transparent room reverb. The early reflections tend to be quieter and slightly delayed while the reverb body is thicker and the decay time is longer.

Chamber reverbs tend to be the more neutral option in terms of acoustic-type reverbs.

Chamber-type reverbs, in different reverb units, could carry the label of studio.

Hall

Hall reverb refers to the reverb of a concert hall. Any concert hall worth visiting for a performance has been carefully designed to offer a pleasing acoustic environment for the listeners.

Hall reverbs generally have a decent amount of pre-delay (5 – 30 ms is typical) with gentle early reflections and decay tails in the range of 2 seconds or more. The density of the reverb body generally builds up toward the tail end the reverb rather than near the beginning (as it generally does in room and hall reverbs).

Hall-type reverb, in different reverb units, can be labelled as club.

Cathedral

Cathedral reverb refers to the reverb we’d hear in a large church or cathedral. These acoustic spaces are characterized by huge spaces with high ceilings, and highly-reflective surfaces at plenty of different angles.

Cathedral reverbs generally have quiet early reflections and long decay times reaching upward of 10 seconds and beyond. The density of the reverb increases as the reverb tails out, leading to a thicker sound and a much more noticeable effect.

Cathedral-type reverb is sometimes labelled, in different reverb units, as church, chapel, stairwell, cave, stadium and other names. Some of these presets/modes will have differing settings (notably in the early reflections) but will all tend to produce a Cathedral-like reverb sound.

Ambience

Ambience reverb aims to recreate the sound of reverb in a free-field. That is to say, not much noticeable reverb at all since free-field spaces do not typically have reflective surfaces (except the floor).

Ambience reverb is defined by a very short decay tail (in the range of 500 ms or less) and is reliant on the early reflections to make it noticeable. Ambience reverb, then, tends to sound more like a slapback delay than a reverb, although it certainly is different.

Emulations

Producing these types of reverb effects made for a cool technique. However, it’s practically impossible to use this effect live; it’s difficult to vary the decay time, and it doesn’t come in a stompbox format! Or does it?

Many reverb pedals on the market will offer one or more of the above “acoustic” options. The digital signal processing of modern reverb pedals can accurately mimic the sound of the above-mentioned acoustic spaces.

So, no, a pedal can’t really become a room, chamber, hall, cathedral or free-field ambience space. However, a good digital reverb pedal will be able to emulate each of these different reverbs digitally and effectively alter the audio signal to reflect a real-world reverb.

The Electro-Harmonix Oceans 11 (link to check the price on Amazon) is an awesome example of a digital reverb pedal with various selectable emulations.

It features the following emulations:

  • Hall
  • Spring
  • Plate
  • Reverse
  • Echo (a delay effect sent into the Plate reverb)
  • Tremolo (the Hall reverb sent through a tremolo)
  • Modulation (reverb plus chorus, flanger or both)
  • Dynamic (swell/bloom, gate or duck/side-chaining effects applied to the reverb)
  • Auto-Infinite (an infinite reverb that is retriggered with each new note)
  • Shimmer
  • Polyphonic (a Shimmer reverb with multiple programmable intervals)
Electro-Harmonix Oceans 11

Electro-Harmonix is featured in My New Microphone’s Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.


Spring Reverb

Spring reverb is one of the two types of mechanical reverbs we’ll discuss in this article (the other being the plate reverb).

Spring reverb, as the name suggests, is produced by vibrating a spring and recording the results. One end of the spring is vibrated by an input transducer (that converts the audio signal into physical vibrations). The other end of the spring is connected to an output transducer (that converts the spring vibrations back into audio).

The spring vibration mimics the sound of reverb. It has an input that accepts the dry/unprocessed signal and an output that outputs the reverb-effected signal.

Spring reverb is often described as metallic, bouncy, smooth, unnatural and dark.

Spring reverbs can be designed with short to medium decay times. They nearly all have a very fast and pronounced early reflections and significant damping.

Like acoustic reverb, there is damping in a spring. Higher frequencies have a more difficult time vibrating the spring. However, the damping in spring reverbs is often more detrimental to the high-end of the signal than acoustic verbs.

The key part in understanding a spring reverb is that it’s mechanical and will not emulate the sound of an actual acoustic space.

The Danelectro Spring King (link to check the price on Amazon) is the real deal. It’s a spring reverb with an actual spring built into its design. This design, in a pedal format, is rare indeed.

Danelectro Spring King

As previously mentioned, 1985 brought forth two of the first and only analog reverb pedals (the DOD FX45 and the Arion SRV-1).

The Arion SRV-1 was an analog reverb pedal designed to emulate spring reverb through a BBD circuit.

The Catalinbread Topanga (link to check the price on Amazon) is a fantastic digital reverb pedal aimed at recreating the spring reverb sound.

Catalinbread Topanga

Catalinbread is featured in My New Microphone’s Top 11 Best Boutique Guitar/Bass Pedal Brands To Know & Use.


Plate Reverb

The plate reverb is the other type of mechanical reverb. Like the spring reverb, it is based on a vibrating piece of metal, only this time it’s a thin plate/sheet, similar to a speaker cone.

An input transducer will convert the audio signal into a mechanical vibration to get the plate moving. As the plate vibrates, an output transducer will convert these vibration, which sound like the input signal with reverb, into an electrical audio signal.

Plate reverb is often described as metallic, eerie and unnatural. Their reverb bodies and tails are relatively dark though the initial reflections are often very bright.

Plate reverbs can be designed with short, medium, or long decay times. They nearly all have a very fast and pronounced early reflections.

Again, the key part in understanding a mechanical reverb like the plate reverb is that it will not emulate the sound of an actual acoustic space.

The Catalinbread Talisman (link to check the price on Amazon) is a digital reverb pedal designed to emulate the sound of a vintage 7′ x 4′ plate reverb.

Catalinbread Talisman

A Note On Digital Reverbs

We’ve discussed physical spaces and mechanical reverbs. We’ll begin our discussion of digital reverbs with the convolution reverb in a moment.

First, though, it’s important to note that with digital emulation we can achieve any of the reverbs listed above with digital signal processing (DSP). As we’ve discussed, practically all reverb effects pedals use DSP to produce their reverb effect.

DSP is easily programmable and can get us to the sound we need. Parameters can also be adjusted to get us to the exact sound we want.

Not only is DSP awesome but achieving reverb in a pedal any other way will lead to rather lacklustre results.

  • Analog circuits (often based on bucket-brigade devices) are limited in decay time and are rather noisy and distorted. They struggle to produce reverb.
  • Springs and plates are clunky and limited in functionality. They also take up space which is a concern for stompbox pedals.
  • It’s physically impossible to put an actual acoustic recording environment into a pedal.

So then, digital reigns supreme when it comes to reverb pedals!

The main point to note is that, although we’re getting into a discussion about digital-type reverbs, the above-listed types are also available in digital pedals due to DSP.

The Strymon Big Sky (link to check the price on Amazon) 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)
Strymon Big Sky

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


Convolution Reverb

Convolution reverb is achievable through a rather involved process. A physical acoustic space is recorded, sampled and analyzed thoroughly. Profiles are made for the initial reflections, decay time and frequency damping. An algortihm is then created to simulate that physical space.

Convolution reverbs paved the way for digital reverbs. Today we can emulate space without any samples so convolution verbs are rarely ever used.


Bloom Reverb

Bloom reverb, as the name suggests, blooms into fruition as the reverb evolves.

This reverb type is exceptionally unnatural. It has very quiet initial reflections that continuously increase in amplitude until a certain point where the reverb tail is kicked in.


Shimmer Reverb

Shimmer effects in reverb and delay are essentially a time-based effect (reverb or delay) combined with a pitch-shifting effect.

Shimmer reverb, then is an effect that pitches up the wet reverb signal (typically by an octave) relative to the dry/direct signal.

This effect gives the overall sound a “shimmering effect” hence its name.


Gated Reverb

Gated reverb combines reverb and a noise gate into a single effect. Of course, like shimmer, this could also be achieved with two separate effects.

That being said, gated reverb takes a reverb type (often room or chamber) and cuts off the decay once the reverb body drops below a certain amplitude.

That’s effectively what a noise gate is designed to do: to mute the signal as soon as it drop below a set amplitude threshold. Applying this to reverb offers an abrupt cut off of the reverb at certain amplitude threshold.

Gated verb works well on transient signals. It’s perhaps most famously heard on snare drums from 1980’s recordings.


Reverse Reverb

Reverse reverb isn’t really an effect we’ll find on a reverb unit. Rather, it’s a mixing effect that takes a recording of a reverb tail and reverses it.

This effect can often be heard in film scoring (particularly in horror and sci-fi) as well as in experimental and EDM music.

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Controls Of Reverb Pedals

If we think of acoustic spaces, there are plenty of parameters that can change the sound and reverberation of the environment. Reverb pedals will generally have controls similar to these parameters and perhaps even a few others.

Here are the controls we’ll most often find on reverb pedals:

Mode/Type/Model

As we’ve discussed, the overwhelming majority of reverb pedals are made with digital circuits designed to emulate the sound of real reverberation. The great thing about digital circuits is that so much information and processing can be included.

For many reverb pedals, there are different modes (sometimes referred to as types, models, or some variation of the word) that are selectable by the user.

These modes generally refer to any of the reverb types listed above. To reiterate, they are:

Some pedals have other special modes to select from.

Mix (Effect Level)

This control blends the direct “dry” signal level with the reverberant “wet” signal level at the output mixer.

Pre-Delay

Pre-delay, in the real world, is the time between the source sound and the onset of reverberation.

Reverb pedals emulate this with a pre-delay control that adjusts the time between the dry signal and the onset of the wet reverb-effected signal in the pedal’s output.

Longer pre-delay times represent a larger environment with surfaces that are further from the source.

Decay Time

The decay time control alters the time it takes for the reverb reflections to die away in the signal.

This control is sometimes labelled simply as “time”.

Damping

Damping (sometimes labelled to as “tone”) controls the reduction of the high-frequency content in the wet reverb signal.

In nature, high frequencies are more easily absorbed by surfaces and so damping is naturally occurring. The damp control on a pedal aims to define this parameter.

Increasing daming will help to free up the high-end in a mix and promote a warmer guitar sound.

Preset Recall

Some more involved reverb pedals will be capable of saving and recalling use-defined presets. This is similar to aforementioned mode control except that we get to define the different settings.

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Tips On Using A Reverb Pedal

There’s a lot you can do with a seemingly simple reverb pedal.

Here are some tips to help get the most out of your reverb pedal.

Give It A Break

Sure, this isn’t really get more out of the pedal. In fact it’s quite the opposite. That being said, sometimes less is more.

By bypassing the reverb pedal during a performance, we can get a greater, more dynamic effect when we finally engage it.

Of course, having a reverb on the entire time can really give a strong sense of space in the mix. However, we can get a much more noticeable effect out of our reverb pedal(s) by engaging and disengaging them at certain points in the performance.

Max Out The Mix

This is a mixing trick I like to use from time to time. It can also be done with a reverb pedal for special effect in live and studio settings.

Maxing out the mix will leave nothing but the reverb-affected signal. Having only the initial reflections, reverb body and reverb tail can yield interesting results.

Try turning the other controls all the way up or all the way down while the mix is at 100%. I bet you’ll find something strange and, possibly, creatively inspiring.

Modulate The Decay Time While Playing

Modulating the decay time while playing will give this weird pitch-bending effect.

Think Of Time And Space

To get the most out of your reverb pedal, think of it as a tool to put your guitar (or other instrument) into a physical space.

Where do you want to be playing? A well or a coat closet?

Where are the other instruments playing? Are they in the same room?

Do you want to play in the same reverberant space as everyone else or should you stand out during the performance.

Ask yourself these types of questions and adjust your reverb pedal to the answers you come up with.

Produce Ambience

Ambience can add production quality to your music, sound design and scoring.

There’s a ton of scenarios for ambience.

Awe-inspiring ambiences can be produced with a reverb pedal by turning up many of the controls.

Having long decay times and plenty of mix will produce larger-than-life ambiences.

Err On The Side Of Shorter Decay Times In A Mix

On the slip side of ambience, it’s often best to keep reverb subtle.

If you’re playing in a band with lots of moving parts (ie: anything other than ambient music), then it’s like best to keep reverb settings modest for most of the time.

Overdoing it on reverb can quickly drown out your instrument or the instruments of others and can really ruin a mix quickly.

Utilize Stereo Outputs And Direct Outputs

Many reverb pedals have either stereo outputs; direct and effected outputs, or both.

Try sending each output to its separate amplifier or to its own preamp in the studio. This can yield awesome stereo effects and give us more control over our reverberant tone.

Try Putting The Reverb Pedal Before Other Effects Pedals

As we’ll discuss in the next section, reverb sounds best at the end of the pedalboard signal chain. This is because it’s a time-based effect that alters the dimension of the signal. It’s much easier for pedals to read and effect dry (no reverb) signals.

That being said, putting reverb before another pedal or several pedals could yield interesting results. A personal favourite is running a reverb pedal into a tremolo pedal.

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Where Should Reverb Pedals Go In The Signal Chain?

Reverb is a time-based effect and, therefore, works best near the end of a signal chain or, rather, after the utility, gain-based and modulation pedals (which pretty well sum up all pedals except delay and reverb).

By having the reverb pedal at or near the end of the signal chain (just before the amplifier), the reverb circuit will have a strong “dry” signal to effect.

It also means that the pedals before the reverb pedal will not be tasked with effecting a “wet” reverberant signal. Most pedals will perform better when shaping the tone of a dry signal than when trying to give space to a signal with reverb.

Of course, experimentation is also a fun exercise and putting reverb pedals earlier in a signal chain can yield interesting and usable sounds as well!

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

To learn about all pedal types, check out my article The Full List & Description Of Guitar Pedal Types.

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Can you use a guitar reverb pedal for vocals? Reverb pedal can absolutely be used to affect vocals. Vocal signals can be routed through pedals in live, recording and practice situations. The vocal signal can be routed from a preamp or an output of a device with vocals prerecorded. A vocal mic should have a preamp/impedance converter (and phantom power supply, if required) put in line between it and the pedal if plugging “directly”.

Can you plug a microphone into a guitar pedal? Microphones can be plugged into guitar pedals with a few tweaks and components in-line between the two devices. A mic preamp should be used to raise the mic signal level and impedance to properly drive the pedal. A phantom power supply will be needed if the mic needs +48V. Finally, we need some way to convert the XLR output of the mix into a 1/4″ TS cable for the mic input (typically achievable via the preamp).

Related article: How To Plug A Microphone Into A Guitar Or Bass Amp

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