Home » Microphone » What Is Microphone Gain And How Does It Affect Mic Signals?

What Is Microphone Gain And How Does It Affect Mic Signals?

Whenever you buy a mixer, a preamp, or even certain microphones, you will have seen the word ‘Gain’ written on it. It is a strange control that often does not have any numbers or level indicators. So what is microphone gain, and how does it affect mic signals?

The gain control is an electrical circuit that the audio signal passes through after leaving the microphone. Adjusting and using it correctly will provide a clear sound when you are recording or for those listening. It will also improve the tonal quality of your audio.

Is Gain the Same As Volume?

Or, in other words… Is there a difference between Gain and Volume? Some think that they are basically the same thing and just have different names. If they do different things, does it matter? The answer to that is a definite yes.

It is important to understand the difference between Volume and Gain. When you do, it will change the tonal quality of whatever it is you record, play, or sing forever. But before we get to that, let’s make sure we understand exactly what Gain and Volume are.

What is Volume?

What is Volume

Let’s start with this one because it is the easiest to explain. Volume usually means the output sound level, which is measured in decibels.

If you want it in very simple terms, it is how loud the sound is after that it has been processed. It is how loud the sound that you can hear is.

In Practical Terms

If you are mixing music, it is the level you send to your stereo output from the individual channel. If you are playing a guitar through an amp, then the volume is how loud you turn up the amp. Or, if you are driving, it is how loud the music coming from your car system is.

Basically, Volume equals Loudness. However, it is important to remember that while volume increases the loudness, it does not change the sound quality of what you are hearing. It just becomes louder. 

The exception to that rule is if you are overloading a part of a system, such as an amp or a speaker, which would then produce distortion, which would then affect the sound quality. But, as long as nothing is being overloaded, an increase in volume has no effect on the sonic quality of the sound.

If That is Volume, Then What is Gain?

Back in the good old analog days, gain was a simple concept to understand. But in our modern digital world, it has become a little more confusing as it has come to mean different things.

This can be partly blamed on the manufacturer’s desire to try to recreate and copy analog equipment while plowing on with their own development ideas.

Definitions Can Become Confused

Some people have started using the word gain as a reference to volume. That is ‘volume out,’ as opposed to ‘volume in’ to a system. This can often be seen on digital plugins. You may see a function labeled ‘makeup gain’ on a compressor. This refers to an adjustment to compensate for the output volume but has been given another name.

The more definitive description is that gain is the decibel input into a system. Therefore the Gain will control the volume, or how loud something is, in advance of any processing that takes place. It is the level of volume that is being input to preamps, plugins, or amplifiers, i.e., their input, not their output.

An Important Distinction

It is very important to appreciate this distinction. After any processing, the volume of the output will not change the sound’s tonal features. But the gain, or more specifically, how high it is, before processing, will.

Microphone Gain

So, how does gain affect microphone signals? Before we go into that, I am going to be using the word ‘amplitude.’ Let’s just make sure we all know exactly what that is.


Sound waves create sound, and sounds are made by molecular vibrations. When you hit a cymbal or a drum, it vibrates. Vibrations, in turn, make the molecules in the air move, and they travel away from the source of the vibration.

These molecules reach your ears, and your eardrum vibrates. The bones in the ear then start to vibrate in exactly the same way as the original sound wave vibrated.

There are two important elements of the vibration. The frequency, how often the wave vibrates, and the amplitude or the size of the vibration. Both will affect the sound of any object.

The Size of the Vibration

This is the amplitude, and it will determine how loud something is. If you were to see the waves on a graph, the louder the sound, the larger the sound wave. Larger vibrations make louder sounds.

The amplitude is a measurement of the intensity and the strength of the sound wave. To measure this, we use a Sound Pressure Level or SPL meter. You have no doubt come across SPL readings when looking at the specifications of microphones.

So Why Am I Telling You All This?

Because amplitude is increased by Microphone gain, the more gain you apply then, the bigger the wave. Therefore the louder the sound you are about to put through your processing options.

So microphone gain will increase the signal’s amplitude. And it will also boost the strength of the signal to line level from mic level. This makes the signal compatible with professional-level audio equipment.

The gain is controlled by a microphone preamp which is the first electrical circuit that the signal will encounter after output from the mic.

What Is Microphone Gain And How Does It Affect Mic Signals? – Line Level and Mic Level

What Is Microphone Gain

A microphone will give a nominal output of something between −60 dBu and −40 dBu. But professional equipment works at line level. This is nominally +4 dBu. By professional equipment, I mean digital audio workstations and good quality mixing consoles.

These are just average values, and the actual values can be slightly different. They can vary due to:

  • The loudness at the source of the sound
  • Distance between the mic and the source of the sound.
  • Sensitivity of the mic.
  • The level of Gain that has been applied to the mic signal.

There are some other factors, but these are the most common.

Line level is considerably stronger than mic level. You, therefore, need to significantly boost the mic level signal to make them compatible. Normally a boost of between 44 dB to 64 dB will be adequate, again depending on the above factors.

The Different Types of Signals

Microphones are designed to output mic-level signals. This signal is then sent to a preamp (a ‘pre’ amplifier) which then boosts it to a level that is usable and will create the desired quality of sound. For some excellent preamp options, take a look at our comprehensive reviews of the Best Microphone Preamp you can buy.

Similarly, Line Level inputs are designed to receive line-level signals. Therefore, if you plug a microphone straight into a line level input, the result will not be good. You will get a very low-level signal that you can barely hear, and the signal-to-noise ratio will be very bad with more hiss than the actual signal.

Two Possible Microphone Gains

The gain of the preamp provides the boost that the signal needs to get it to line level.

This can occur in two different ways:

  • Gain can be applied using a preamp inside the mic, in the case of an ‘active’ mic. An external power source such as an AC wall connection, USB power, or batteries will supply the power needed.
  • Gain that is applied using a separate preamp which could be an audio interface, mixing desk, or a standalone preamp.

In the case of Option 1, the circuitry is inside the mic. In Option 2, the signal gets its gain after leaving the microphone. Let’s look at both of these options a little closer.

Gain from the Preamp Inside the Mic

Active microphones are built with a preamp inserted directly after the capsule inside the microphone body. It can increase the voltage and also decrease the impedance of the signal. Lower impedances are better because the signal isn’t degraded traveling through cables as it is if the impedance is high.

Some active mics are also fitted with attenuation pad switches. This decreases the amplitude of the output signal to prevent distortion, which could be caused by overloading the mic if, for example, it was positioned next to a kick drum.

The different types of Active Microphones

There are two basic types of active microphone. In the traditional world, there are condenser mics that need phantom power to function. These are very sensitive and need an external power source (phantom power) either sent down the microphone cable from an audio interface, preamp, or mixing desk, or some will run off their own dedicated mains connected power supply.

Even though they are self-powered, they do not produce enough power to get the signal to line level; therefore, they have to be connected to a mixing console, a dedicated preamp, or an audio interface to provide the increase in gain needed to produce a quality signal level. However, when matched to the right preamp, they produce fantastic sonic results.

In the modern world, there are USB and battery-powered microphones. These are, as you would expect, powered by USB or batteries, and are normally used for online conversations such as Skype. Messenger, etc., and for podcasting, blogging and vlogging. They are rarely used in professional recording.

These types of microphones are connected directly to a PC or Mac via USB. Therefore, they do not require an audio interface or any type of preamp and boost the signal internally to the desired level for the computer to create the correct signal level. This does not usually produce what could be termed ‘professional’ audio quality, which is why they tend not to be used for professional recording.

Gain Applied From a Separate Preamp

We have seen that microphones output mic-level signals. We have also seen that they require gain to make them compatible with line level. Microphone preamps will give you this gain.

Working With a Standalone preamp

A mixing console will usually have built-in preamps. But many sound engineers still prefer to use standalone preamps as the quality is better and the ability to experiment sonically more varied.

If you are connecting a standalone preamp, make sure that the preamp signal is going to a line input and not a mic input. Standalone preamps can also be connected up to a DAW through a digital interface or an analog to digital converter. 

The DAW (Digital Audio Workstation) will need an audio interface to accept various signals; many of these will feature mic inputs, including built-in preamps. For some great options, check out our in-depth reviews of the Best Audio Interface, the Best USB Audio Interfaces, and the Best iPad Audio Interface currently on the market.

Preparing the Mic

The role of the mic preamp is, therefore, obvious. It is the first circuit that the signal from the mic will pass through. At this stage, the mic preamp is preparing the signal from the microphone to work with other audio devices. It may also provide the microphone with +48 volt phantom power if needed.

Does Microphone Gain Affect the Microphone signals?

Microphone signals

We have established that the role of microphone gain is to take the mic level signal and boost it to line level so that it is at the correct level to give the maximum sound quality. But how much gain you will require to do this will depend on a couple of things.

Firstly, how sensitive is the mic you are using? That is, the output signal relative to the Sound Pressure Level, or SPL. Understandably, a more sensitive mic will usually require less gain.

Secondly, how close is the mic to the source of the sound? A mic may require less gain depending on the proximity to the source. A good example is a drum. A mic placed close to a snare would need less gain than one positioned farther away.

So, let’s look at proximity briefly.

Distance First

Every mic has its own individual proximity effect. If you position it too close to a source, it is likely to emphasize the low frequencies and get bassy. Distance matters when setting the mic up. So, don’t get too close or, of course, too far away unless you want to use the proximity effect to get a certain sound or tonal quality.

The tone, especially of a vocal, will be affected by the distance the mic is from the source. Therefore, get the tone you want first and then adjust the gain accordingly. Don’t adjust the gain, thinking it is a volume control. It isn’t.

Don’t Overdo It

When you are applying gain to a microphone signal, don’t overdo it. It is easy to give it too much, and for it to start ‘clipping.’ In the good old days of analog, we used to push things to the max for a number of reasons. The first was that the sound to noise ratio of tape was terrible, and if you didn’t have a strong signal, you would end up with more hiss than the actual sound the instrument made.

The second reason was that because everything was analog, digital clipping didn’t exist. If you pushed things too far, it saturated (or distorted, but in a nice way). You could then use this to create a better sound.

However, it is very different with digital technology; if digital clips, the result is always negative with drop-outs, clicks, or beeps ending up on the recording. That’s why interfaces, preamps, and consoles usually have an indicator light, often in red, that will warn you that the input gain is too high. Some devices also have a yellow signal before it goes red to let you know that you are getting close. 

But for digital recording, it’s always best to keep the signal in the green, with an occasional yellow, but never in the red.

What About Using a USB/Digital Mic

The advent of the USB mic has added some interesting design developments. These mics have built-in ADC’s, Analog-Digital Converters, and also have a preamp built-in. The preamp is placed in front of the ADC, so it is still the first thing the mic signal encounters.

The preamp has enough adjustable gain to produce a signal that the PC or Mac needs for a quality signal level.

So, What is Gain Staging…

I’m not going to get into this too deeply because it is complex enough for an entire article. But in its most basic form, gain staging occurs when you are using two or more pieces of equipment that feature a gain control. For example, a compressor and a preamp.

You may be running your microphone straight into a preamp, which then sends to signal to a hardware compressor before returning it to the preamp, which then goes to the line level in of your audio interface. You could also run them in sequence if your preamp does not have a send and return.

This gives you two different gain controls, one for the compressor and one for the preamp. How you set these two gain controls will have a great effect on the sound, allowing you to sculpt it in any way you want. For example, by pushing the gain on the compressor, you are sending more gain into the preamp, which can saturate it, producing a thicker, more substantial sound.

The key to effective gain staging is to continually experiment until you end up with the sound you want, always remembering that the final signal does not clip the digital threshold.

What Is Microphone Gain And How Does It Affect Mic Signals? – The Right Equipment

However, regardless of what you are recording, you will need some quality equipment to get the results you are looking for. For starters, you will need a great mic. This can be expensive for some, but for the price point, there aren’t many better than this AKG Pro Audio C414 XLII Vocal Condenser Microphone.

Or, if you prefer the more affordable USB option, there is the Blue Yeti USB Microphone. This is more of a budget range mic but does a decent job for podcasting, blogging, vlogging, and basic home recording.

And one of the best Audio Interfaces from the Rupert Neve Dynasty, check out the Focusrite Scarlett 4i4 3rd gen. And from the same company, a dedicated stand-alone microphone preamp, the Focusrite ISA One Classic Single-channel Mic Pre-Amplifier with Independent D.I.

Looking for some high-quality Audio Interfaces or Microphones?

Then take a look at our in-depth PreSonus Audiobox USB 96 Review, our Focusrite Clarett 4Pre USB Review, our Behringer UMC22 Review, our Focusrite Scarlett Solo Gen 3 Review, our Behringer UCA202 Review, our Focusrite Scarlett 2i2 Gen 3 Review, as well as our Behringer Audio Interface 4 Channel UMC404HD Review.

You may also be interested in our comprehensive reviews of the Best Vocal Mics, the Best Kick Drum Mic, the Best Dynamic Microphones, the Best Microphones for Recording Rap Vocals, the Best Microphones Recording Electric Guitar you can buy in 2023. 

What Is Microphone Gain And How Does It Affect Mic Signals – Final Thoughts

Gain versus Volume

The reason we have a gain control is to adjust the input signal level of an instrument and voice to ensure that it is at the perfect level for recording. The reason we have volume control is to be able to create the right balance of each voice and instrument in the mix.

Therefore, Gain adjustments come first, Volume adjustments come second.

It all seems so simple when you explain it like that.

Happy recording!

Related Posts
5/5 - (84 votes)

Leave a Comment

Your email address will not be published. Required fields are marked *

About Corey Hoffman

Corey is a multi-instrumentalist who has played in numerous bands over the years, some good, some not so good. He has also written countless songs and recorded five albums in professional studios across America. Today he is a hobby musician but still loves the guitar after over 15 years of playing.

He considers his writing as a way to share what he has learned over the decades with younger generations ad always can't wait to get his hands on the latest gear.

He lives just outside New York with his wife Barbara and their two German Shepherds, Ziggy and Iggy.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top