Microphones come in different types and are meant to work a certain way.
There’s no such thing as the universal microphone.
For example, dynamic microphones are meant for stage work and are mostly common in broadcast media like podcasts.
They’re internal circuitry allows them to be the mic of choice of many musicians looking to do loud work.
To properly use dynamic microphones you need to know their limitations.
This post will discuss gain and dynamic mics as a response to a question that I get often.
With that said, let’s discuss why dynamic microphones need a lot of gain?
Dynamic microphones don’t pack enough voltage on their own to boost a signal this is why they need a lot of gain to boost their signal strength from mic level (which is quite) to line level which is loud. Pre-amps usually provide this boost.
Therefore, dynamic microphones require higher levels of gain, perfect placement, and a preamp to output some good volume.
What is gain?
Gain basically works by adding energy to a signal.
Therefore, to bring mic level signals up to line level, a preamplifier is required to boost it.
Some microphones have a built-in preamp and this usually has enough gain to boost the mic signal up to line level.
If a mic doesn’t have an active preamplifier, gain can be added from a separate microphone amplifier such as audio interfaces, preamps, or from a mixing consoles.
When the amp applies gain to the microphone’s input signal, this then creates a stronger output signal.
Microphone volume is simply how loud or quiet the output sound from the mic is.
You usually adjust the volume of the mic by using a fader…if you have the mic connected to a computer, this control can also be adjusted from the device settings.
The louder the signal into the mic, the louder the output.
However, if you have the volume muted no amount of input will project any sound back out.
The difference between gain and volume
The main thing to know about these two things…. is that microphone gain refers to an increase in the strength of the mic signal, while microphone volume simply controls the loudness of a sound.
Microphone gain relies on an amplifier to boost the output signals coming from the mic… to ensure that they are strong enough to be compatible and usable with other audio equipment.
Microphone volume, on the other hand, is simply a control that you’ll find on most mics… it is used to adjust how loud the sounds coming out of the mic are.
Uses of Mic gain, Uses of Mic volume
The main use of microphone gain is to adjust the mic so that it’s signal strength gets closer to the nominal level.
This gain boost can also be applied to other instruments as much as it can to the signals that are coming out of a microphone.
The purpose of volume is to control the level or loudness of sound being projected out of a mic.
Recording studios usually use these volume controls to strike the right balance between each microphone and instrument in operation.
When it comes to both microphone gain and volume, gain adjustments should be handled before any volume changes are made.
What Does Gain Do?
Let’s use two easy examples that…
The first is that of a microphone preamplifier, the second is that of an analog-to-digital converter.
They’re all simple signal paths but they all have unique scenarios at the output, which makes this easy to understand.
Microphones record at what is called “mic level,” which is a very quiet signal because there’s really not a lot of amplitude.
This has to do with how microphones are made and how they have to be very sensitive in order to pick up timely details in the audio they’re capturing.
Therefore, its necessary to turn up the volume on the input mic signal.
This is done with a mic pre-amp.
Analog-to-digital Converter or ADC
Continuing on from the previous audio we’ve recorded in and sent to the preamp.
It will next pass through an analog-to-digital converter (ADC), which exists in your computer’s soundcard or could be an external audio interface.
(All analog-to-digital converters have amplitude issues)
So now our ADC converts analog electrical signals into digital ones that can be understood by your computer.
Your computer reads the voltage and current to understand the loudness and frequencies involved in the audio.
It’s important to know that there’s an optimum loudness level that allows the ADC (e.g. audio interface) to create the highest quality recording.
Furthermore, you need the loudest possible audio going
through this converter…. a loud signal fills in all bits and nuance and provides the computer with as much information as possible about the signal.
The more information, the higher the quality of the audio playback from the computer because it would have had enough information to create the best reconstruction of the audio signal digitally.
However, if you go too loud, you’ll get distortion …which is in the form of clipping due to there being a maximum voltage allowed within the system.
This is the final reason we have input gain knobs and why gain is such a crucial factor..
By getting as close as possible to the maximum voltage, we are able to produce the highest quality audio allowed by the system.
Gain allows you to increase the loudness inside of an audio system, which absolutely determines the quality of the sound or recording. This is one of the reasons why it’s necessary for dynamic microphones that naturally don’t have enough natural volume.