If you’re reading this article, chances are you use microphones regularly: on your cellphone, in your computer, etc. But if you want to learn how to optimize your use of more professional microphones for better audio, this is the article for you!
How to use a microphone: To properly use a microphone, we must power it correctly (if it’s active) and connect it to an input that will accept its audio signal (typically a mic preamp). Then, we should strive to position the mic in the best way to capture the intended sound source.
This article will provide with an in-depth guide to using microphones: from connecting the microphone; powering the microphone (if it’s active); positioning the microphone properly; and providing the mic signal with proper gain.
How To Use A Microphone
In the simplest terms, there are 4 key actions when using a microphone:
- Connecting the microphone to the mic preamp input.
- Powering the microphone (if it requires power).
- Positioning the microphone.
- Applying gain to the microphone signal.
Knowing these 4 steps will allow to use any microphone (or at least figure out how to use any microphone). This article will focus on these 4 steps.
However, there are plenty of factors that go into properly using a microphone. Covering them all in one article would be exhaustive (and make for an incredibly long read).
I mention a lot of topics in this article. In order to make this as condensed as I can, I’ve added links to other My New Microphones that go into greater detail about the topics I mention briefly throughout this article. If anything catches your attention, I encourage you to check out the linked article to gather more info before continuing on with this article!
With that out of the way, here is how to use a microphone!
Connecting A Microphone To A Mic Input
Although a microphone by itself could technically work, in order to properly use a microphone, we need to connect it to a device that will effectively use its output signal.
This connection is always made through a mic input. Note that microphones can technically plug into any audio input given the proper connectors, but for the purposes of this article, we’ll talk about mic inputs.
The various devices microphones connect to include:
- Microphone preamps.
- Mixing boards.
- Audio recorders.
- Audio interfaces.
- In-line devices (pads, high-pass filters, phantom power supplies, RFI filters, etc.).
- Cell phones.
The various connectors microphones use to connect to the above devices include:
- XLR (3-pin, 5-pin, 7-pin, or other variant)
- TS (2.5mm, 3.5mm (1/8″), or 1/4″)
- TRS (2.5mm, 3.5mm (1/8″), or 1/4″)
- TRRS (2.5mm, 3.5mm (1/8″), or 1/4″)
- TA3 (mini-XLR)
- Tube PS
Note that most mic inputs are mic preamplifiers, which provide the necessary gain to boost the mic level signal to line level. More on this in the Preamp Gain And Using Microphones With Other Equipment section.
XLR Microphone Connections (And Other Analog Connections)
XLR is the most common connection for professional microphones.
XLR is a 3-pin (3-wire) connector that carries balanced audio:
- Pin 1 acts as a ground wire and electromagnetic shield.
- Pin 2 carries the audio signal in positive polarity.
- Pin 3 carries the audio signal in negative polarity.
Carrying the same audio signal with opposite polarity on pins 2 and 3 means the XLR cable is balanced. At the mic preamp (which we’ll discuss later in this article), a differential amplifier sums the difference in amplitude between pins 2 and 3, creating a signal twice as strong as the audio signal carried on the pins themselves.
This differential amp, at the same time, cancels out any noise that is common on both pins (including EMI, RFI, and even +48V DC phantom power, which isn’t really noise).
Because the XLR cable is balanced, it can also carry phantom power (an equal +48V DC on pins 2 and 3) to microphones that require it. More on phantom power in the next section.
Note that, of the above-listed connectors, the Mini-XLR, TRS, Tube PS connectors, and Tuchel are also balanced.
To physically connect with XLR, simply insert the male end “plug” into the female end “jack.”
The microphone (XLRM) plugs into the XLRF of the mic cable (pictured below):
The cable XLRM end plugs into the in-line device’s XLRF which is almost always a mic preamp (pictured below):
For more information on XLR microphone connections, check out my article Why Do Microphones Use XLR Cables?
Wireless Microphone Connections
To connect a microphone wirelessly, we need a wireless transmitter and a wireless receiver that are tuned to the same radio frequency.
Connect the microphone to the transmitter. The transmitter will then embed the mic’s audio signal into a radio signal and transmit it wireless to the receiver.
The receiver then decodes the radio signal, extracting the mic’s audio signal from it. Once decoded, the audio signal is then outputted from the wireless receiver (typically at mic level). The receiver’s output signal should then be connected to a mic preamp, just as a wired mic would be.
Modern wireless microphones often connect to their transmitters via the following connectors (I’ve added examples to show each connection type):
- XLR: (example: Sennheiser SKP 100 G4-A).
- TA3 (mini-XLR): (example: Samson PXD1).
- TA4: (example: Shure GLXD1).
- TRS: (example: Sennheiser EW 112P G4).
The transmitter sends the mic signal wireless to the receiver so long as the frequencies are matched.
The receiver then outputs the signal, typically via:
- XLR: (example: Sennheiser EM 100 G4-A).
- TRS: (example: Sennheiser EK 100 G4).
The wireless receiver then connects to the mic preamp (or other in-line device). This is typically done with an XLR cable or a 3.5mm (1/8″) TRS to XLR adapter cable.
For an in-depth description of how wireless microphones work, check out my article How Do Wireless Microphones Work?
Digital Microphone Connections (USB And Others)
Digital microphones (particularly USB mics) are becoming more and more popular due to their simplicity in improving computer audio.
Connecting a USB microphone is as simple as plugging the proper USB cable into the computer.
Note that in order to connect a microphone digitally, there must be an analog-to-digital converter either built into the mic (in the case of digital mics) or in the adapter cable.
For a more detailed article on digital and analog mics, check out my article Are Microphones Analog Or Digital Devices? (Mic Output Designs).
Tube Power Supply Unit Connectors
If a microphone requires an external power supply (like tube mics do), it’s essential that we plug the microphone into the proper power supply.
PS connectors will generally have a ground pin; pins to carry balanced audio; and pins to carry the proper power. Depending on the microphone, we could have different connectors.
The microphone audio will generally run from the mic to the PSU (power supply unit). From the PSU output (typically an XLR connector), the balanced audio can then be sent to the mic preamp.
The Other Connectors
Though there are plenty of microphone connections on the market, we’ve covered the main ones that you’ll see the most often.
The most confusion about microphone connectors comes with lavalier mics and their wireless transmitters, which we’ve discuss earlier. As mentioned, the vast majority of professional microphones use XLR.
To read more about the various microphone connections, check out my article What Do Microphones Plug Into? (Full List Of Mic Connections).
Properly Powering Active Microphones
When it comes to passive microphones, simply connecting them to a proper mic preamp will be sufficient to get signal from them. Active microphones, on the other hand, require power (electricity) to function properly.
In other words:
- Passive microphones do not require power (moving-coil dynamics and most ribbon dynamics).
- Active microphones do require power (electret, true, and tube condensers as well as active ribbon dynamics).
In order to use active microphones, we need to power them.
Active Components (What Needs Powering?)
So what makes a microphone active versus passive? It’s the presence versus the absence of active components. The main active microphone components are as follows:
- Externally polarized condenser capsules: Condenser capsules require a fixed charge across the diaphragm and backplate in order to function. In non-electret mics (“true condensers”), this fixed charged is supplied by external powering methods.
- FET/JFET impedance converters: These transistor based impedance converters take the incredibly high-impedance signals from condenser capsules and use them to modulate a low-impedance output signal than can travel through the rest of the mic circuitry. These FETs and JFETs require external powering to provide an electrical current for the capsule signal to modulate.
- Vacuum tubes: Vacuum tubes act as impedance converters and as pseudo-amplifiers in tube mics. They take in the high-impedance signal from the mic capsule and use it to modulate a stronger lower-impedance output signal.
- Printed circuit boards: PCBs sometimes have active components such as amplifiers that require external power.
- Analog-to-digital converters: The ADCs in digital microphones require power in order to properly convert the analog mic signal into digital audio for the mic output.
For further reading on active versus passive microphones, check out my article Do Microphones Need Power To Function Properly?
There are various methods of supplying this power:
- Phantom power.
- DC bias voltage.
- External power supplies.
- USB power.
What is phantom power? Phantom power is a method of powering microphones through balanced cables. A standard +48V DC (though the voltage may range from 9 V – 52 V) is applied through pins 2 and 3 (relative to pin 1). It sufficiently powers the microphones designed for it without affecting the sound the of the mic signal.
Phantom power gets its name from its invisibility. It runs through the same balanced cable that carries microphone audio. In fact, it even runs on the same wires within the cable that carry audio. It does so without being heard.
Phantom power is commonly used with the following components in active microphones:
- Polarizing non-electret condenser capsules.
- Providing the modulated current for FET/JFET impedance converters.
- Powering any amps within the mic.
Note that phantom power is not strong enough to power the vacuum tubes of tube microphones, nor is it used to power the ADCs of digital/USB mics. External power supplies and USB power are used for these purposes, respectively.
Also note that not all condenser microphones require phantom power and that many smaller electret mics (like lavaliers) require a smaller DC bias voltage instead.
Phantom power is provided by most microphone preamplifiers (in mixing boards, recorders, audio interfaces, etc.). It can also be provided by standalone phantom power supply devices.
First phantom powered microphone on the market: Neumann KM 84 (1966).
For more information on phantom power and microphones, check out the following My New Microphone articles:
Do Microphones Need Phantom Power To Work Properly?
Will Phantom Power Damage My Ribbon Microphone?
What is DC bias? DC bias is a method of powering microphones though a single conductor. DC bias ranges from 1.5 to 9V DC and is typically used to power the impedance converting FET or JFET in smaller electret microphones.
DC bias voltage is generally too small to power externally polarized condenser capsules and it is certainly not strong enough to power a vacuum tube.
Therefore, DC bias is generally only used to power the impedance converters (FETs/JFETs) or small electret condenser microphones. The most common example of these mics are lavaliers.
DC bias is often provided by the wireless transmitters of lavalier microphones.
External Power Supply Units
What is an external power supply? Before phantom power and before transistors were used in microphones, all active microphones required external power supplies to polarize their capsules and power their vacuum tubes. Even today, external PSs are required to run the relatively power-hungry vacuum tubes of modern tube mics.
With power-hungry tube microphones, external power supplies are a must. The aforementioned phantom power is just not strong enough to properly heat the vacuum tubes.
In tube mics, the external PSU acts in the following ways:
- Heats up the vacuum tube for proper impedance conversion and pseudo-amplification.
- Polarizes the capsule (most tube microphones use true condenser capsules).
- Powers any other active components in the mic circuitry.
What is USB power? USB power provides 5V DC on pin 4 relative to pin 1 (ground). This voltage is used to power the analog-to-digital converters of USB mics as well as the impedance converters of those USB mics that use electret condenser capsules.
USB power, as the name suggests, is used to power the active components of USB microphones. These components include:
- Analog-to-digital converter.
- FET/JFET impedance converters.
- Internal amplifiers.
Note that USB power is generally not strong enough to polarize true condenser capsules and so USB mics are typically either electret condensers or dynamics.
With electret condensers, the USB power also runs the impedance converters. Dynamic mics do not require these impedance converters.
Note that some audio interfaces and even some standalone phantom power supplies run off of USB power in order to send phantom power to their connected microphones. The USB power, in these cases, is stepped-up in order to supply the proper +48V DC (rather than the +5V DC carried through the USB cable).
Positioning A Microphone
Now that we’ve properly connected and powered our microphones, it’s time to talk about properly positioning them.
Proper microphone positioning is crucial if we want to use our microphone to the best of its abilities.
Properly connecting, powering, and providing gain (which we’ll talk about in the next section) is relatively easy. Microphone placement is an art in and of itself that can really make a difference in the sound quality captured by the mic.
To better understand microphone positioning, we should first understand the mechanics of acoustics and of our microphones. In this article, we’ll touch on the following factors:
- The sound source.
- The acoustic environment.
- On-axis vs. off-axis positioning.
- Inverse square law.
- Proximity effect.
We’ll also talk about miking techniques and stereo miking techniques.
Know The Sound Source
Knowing the sound source is important when first choosing the best microphone and when positioning the microphone to capture the sound source.
For example, a kick drum sounds different from a guitar and a death metal vocal sounds different from a voice over.
Once the right microphone is chosen, it’s time to position it correctly.
Know the sound source you’re intending on capturing and position the mic correctly.
Ask the following questions about the sound source:
- What frequencies does the sound source produce?
- How directional is the sound source?
- What distance does it take for the sound to fully develop its character?
- How loud is the sound source?
- Does the sound source push a lot of air or produce plosive energy?
As an example, let’s take a look at an incredibly common sound source. The human vocal:
The frequencies of vocals vary from person to person. However, speech intelligibility is focused in the range of 3 kHz – 5 kHz. Choose a mic that could accentuate that range.
Vocals are fairly directional, projecting from the front of the vocalist’s mouth. Positioning a microphone in front of the vocalist’s face is ideal.
The character of the human voice doesn’t take long to develop, so positioning the mic close to the vocalist will improve signal-to-noise ratio without overly colouring the sound of the vocal.
Vocals also aren’t too loud, so we can position condenser mics (with low max SPL values) close to the vocalist.
Vocals naturally produce plosives, so positioning the microphone at a fair distance and slightly off-axis can help reduce popping the mic signal.
We would want to position our microphone(s) differently if out intended sound source was a kick drum; full drum kit; acoustic guitar; electric guitar cabinet; piano; etc.
Know The Acoustic Environment
Knowing the acoustic environment helps tremendously in microphone placement.
Soundproof spaces, like many booths in professional studios are acoustically dead. No sound enters from outside the room and no sound reflects off the surfaces in the room.
Therefore, we can position our microphone at the ideal distance and angle from the sound source without worrying about reflections or bleed (unless we put other sound sources in the same room at the same time).
On stages, we must account for the other sound sources and position our mics accordingly. This typically means close-miking our sources.
Another challenge of stages is that they are often reinforced and so feedback is a concern. More on this in the gain-before-feedback section.
In acoustic environments with reflective surfaces, we must take into account the reflections of the space and the reverberation. Depending on the desired results, we should place our mics accordingly. Closer miking leads to a dryer sound source while distant miking picks up a more reverberant sound with the character of the room.
When capturing sound in the outdoors or in more ambient settings, try listening to various positions before placing your mics.
On-Axis Vs. Off-Axis
A microphone (whether directional or omnidirectional) typically sounds the best on-axis (in the “front” direction or where the mic points).
So, in general, we want to position our microphone on-axis toward the intended sound source.
However, if the sound source produces plosives (like the human voice) or pushes a lot of air (like a kick drum), it may be necessary to position the mic slightly off-axis in an effort to reduce the likelihood of the plosives/gusts overloading the microphone.
Note that, as we turn a microphone off-axis, we lose the effectiveness of the microphone (in sensitivity and in frequency response).
Inverse Square Law
The inverse square law states that the intensity of a sound wave is inversely proportional to the square of the distance from the sound source. Thus, sound intensity decreases 50% or ~6 dB SPL for every doubling of distance from the sound source.
Basically this means that the closer we position our microphone to the source, the louder than sound source will be at the microphone. Close-miking yields a stronger signal of the intended sound source.
The proximity effect refers to the increase in bass response in a directional microphone as that microphone gets closer to the intended sound source.
Proximity effect has the greatest effect in bidirectional microphones, but is present in all microphone polar patterns except omnidirectional.
Positioning a directional mic too close to the sound source may very well result in an over-pronounced bass frequency response and a muddy signal. If this is the case, simply back the microphone up (taking into consideration the other mic placement factors here).
To learn more about the proximity effect and what causes it, check out my article In-Depth Guide To Microphone Proximity Effect.
In live sound reinforcement situations (where the microphone is amplified and projected by loudspeakers in the same room), we must be aware of microphone feedback.
In order to get the most gain-before feedback out of your microphone, consider the following mic techniques:
- Choose a directional microphone (ideally a cardioid mic).
- Point the mic and loudspeakers in opposite directions.
- Have the null point(s) of the directional mic face the monitors.
- Position the mic as far from the loudspeakers as practically possible.
- Close-mic the sound source(s).
For more information on gain-before-feedback, check out the following My New Microphone articles:
What Is Microphone Feedback And How To Eliminate It For Good.
12 Methods To Prevent & Eliminate Microphone/Audio Feedback.
There are plenty of miking techniques for various situations (sound sources and acoustic environment combinations).
Use the above questions and factors to help position your microphone in the best location relative to the sound source.
The best tip I have for microphone position is to use your ear.
With omnidirectional microphones, plug one ear and listen with the other. Move around the environment until you hear a sweet spot. Position the omni mic there.
With a cardioid mic, plug one ear and cup the other with your hand. Move around, facing the sound source as you. Find the sweet spot and position the mic there.
With stereo microphones (or coincident and near-coincident pair, which we’ll get to in a moment), listen with both ears until you find the sweet spot and position the mic(s) there.
To improve upon your miking techniques, consider checking out my article Top 23 Tips For Better Microphone Placement.
Stereo Miking Techniques
Stereo recording is the go-to in the music world and oftentimes in the video world. Stereo miking techniques provide a “true stereo image” from the get-go in the recording process.
Stereo miking techniques require at least two microphone capsules (in two mics or in a stereo mic. These mic signals (which are inherently mono) are panned in the mixing/recording stage to fit within a stereo image.
The mic capsules pick up sound sources in different places within the acoustic environment. They do so by the differences in their spacing and the direction in which they point.
There are four main categories for stereo microphone pair techniques to fall into:
- Coincident pair: A stereo pair of directional microphones positioned as close together as possible. The directional capsules are pointed at varying degrees from each other (often 90° or 120°) in order to capture sound in a stereo manner. Coincident pairs have very little phasing issues.
- Near-coincident pair: A stereo pair of directional mics in close proximity to one another that point in different directions. Near coincident pairs provide the closest approximations to the natural way humans hear sound.
- Spaced pair: A stereo pair of microphones (directional or omnidirectional). The mics are positioned at a significant distance from one another, providing a wide stereo image at the expense of possible phase issues.
- Coincident non-pair for mid-side: The mid-side technique is also common. It features a cardioid mic pointing forward toward the sound source and a bidirectional mic pointing at 90° and 270°. The bidirectional signal is duplicated in the mix with one copy hard-panned left and the other hard-panned right with the phase inverted.
For more info on mono and stereo microphones, check out my article Do Microphones Output Mono Or Stereo Signals?
For more information on specific stereo miking techniques, check out my article Top 8 Best Stereo Miking Techniques (With Recommended Mics).
Other Miking Techniques
Note that some microphones are designed to attached directly to the sound source. These include:
- Lavalier/body mics: these mics are typically connected to wireless receivers and attach to the clothing; in the hair; or against the skin of actors and other talents in theatre and film.
- Instrument mics: these mics attach directly to their intended acoustic instruments.
Preamp Gain And Using Microphones With Other Equipment
So we’ve got our microphones connected, powered, and properly positioned. Now let’s discuss how to use the audio signal that microphone outputs.
In order to use microphones with other audio equipment, it’s imperative that we boost the mic level signal [1 to 100 millivolts AC (-60 to -20 dBV]t o a line level signal [~1.23 volts AC (~1.78 dBV or +4 dBu)].
In order to boost mic signals to this level, we require gain (amplification) from mic preamplifiers. Preamps provide gain to our microphone signals so that they can be used with audio mixers and recorders.
Why don’t microphones just output line level signals rather than mic level signals? The transducer components of microphones naturally output weak AC signals. Though it ise possible to put a powered amp inside every mic to boost the signal to line level, we do not because it would require more power to feed the mics and would completely change the current models for processing mic signals.
I’ve wondered this myself. As much as it would be nice to be able to plug our mics directly into line levels, bypassing preamps all together, it just doesn’t make sense from a marketing and gear compatibility standpoint to interally amplify new mics to output line level signals.
To read more about microphone audio signals, check out my article What Is A Microphone Audio Signal, Electrically Speaking?
Using A Microphone Preamp
Preamps are the typical device a microphone plugs into.
Microphone preamps are generally found in the following devices:
- Standalone devices.
- Audio interfaces (ADC + DAC).
- Audio mixers.
- Audio recorders.
Mic preamps most often have female XLR connectors for easy professional mic connection.
Connect the wired microphone (or the receiver of the wireless microphone) into the mic preamp.
Once connected, adjust the gain to a healthy level. This is preferably done with the microphone in position with the intended sound source emitting sound. Ensuring there is no clipping in the preamp or audio channel helps to capture a clean audio signal.
To read more about microphone gain, check out my article What Is Microphone Gain And How Does It Affect Mic Signals?
From Mic Level To Line Level And Line Level To Speaker Level
Let’s break down the signal path and gain stages involved with bring a mic signal up to speaker level, where its captured audio is projected back into the air as sound.
Mic level: this is the signal level outputted by the microphone.
Microphone preamp: this device takes in the microphone’s mic level signal, and adds gain to that signal, boosting it to line level.
Line level: at this level, the audio signal strength is healthy for use in audio mixers and recorders. It is also at a healthy level to get converted to digital audio for digital mixers and digital audio workstations.
Power amp: this amp boosts the line level signal (outputted from the mixers, recorders, audio interfaces, etc.) to speaker level before the signal reaches a loudspeaker.
Speaker level: this analog audio signal level is capable of moving the relatively large diaphragms of loudspeakers so that the audio is turned back into sound for us to enjoy (or not enjoy).
For a deeper read into mic, line, and speaker levels, check out my article Do Microphones Output Mic, Line, Or Instrument Level Signals?
How do you speak into a microphone? When speaking into a microphone, it’s critical to be close to the mic. This allows for a good signal-to-noise ratio (signal = voice, noise = everything else). However, with directional microphones, keep a fair distance (half a foot or so) in order to avoid plosives and excessive proximity effect.
For more information on the above mentioned signal-to-noise ratio, plosives, and proximity effect, check out the following My New Microphone articles:
What Is A Good Signal-To-Noise Ratio For A Microphone?
Top 10 Tips For Eliminating Microphone Pops And Plosives.
In-Depth Guide To Microphone Proximity Effect.
How do I use an external microphone with my smartphone? In order to use an external microphone with a smartphone, we must adapt the mic cable to connect to the 3.5mm TRRS jack of the phone. Alternatively, we can use a bluetooth microphone to connect to the smartphone. Ensure your phone’s audio recording software sees the external mic.
For in-depth reads on connecting external mics to smartphones, check out my article How To Connect An External Microphone To A Smartphone.
For more info on connecting bluetooth microphones to smartphones and computers, check out my article How To Connect A Wireless Microphone To A Computer (+ Bluetooth Mics).