Mic preamp: clearing up the confusion surrounding microphone preamps

One piece of audio recording equipment which causes a lot of confusion is a mic preamp. Much of this confusion seems to stem from uncertainty about what a mic preamp actually is and the purpose it serves. In this article, I’ll address some of the confusing factors surrounding mic preamps and provide you with the details that you need to know.

What does a mic preamp do?

First of all, lets address what a mic preamp actually does. A mic preamp, short for microphone pre-amplifier, is a device which is used to amplify the level of a microphone signal from mic level to line level. The level of the signal which a microphone produces is very low. So you require a preamp to boost the signal’s level.

Do I NEED a mic preamp?

The short answer to this is yes, you have to use a preamp when you record a microphone’s signal. Without it, the signal would not be loud enough to use.

Does that mean I have to buy a mic preamp?

This is where the confusion sets in. People often assume that because a preamp is essential for boosting microphone signals to a usable level, that they need to buy one. What many people don’t realize is that, if you already have an audio interface with mic inputs, then you already have preamps. You see, any mic input on your interface has to have a preamp. So you don’t need to go out and buy an additional mic preamp. Your interface’s built in mic preamps serve the purpose of amplifying your mic input from mic level to line level.

Just because your audio interface has built in preamps however, doesn’t necessarily mean that you shouldn’t still buy an external one…

Why might I choose to buy an external mic preamp?

To understand this, it helps to first understand that audio interfaces and mic preamps are not the same thing. We’ve already established that an audio interface with mic inputs will be equipped with built in mic preamps. But you are also able to buy mic preamps as external units which do not do the same thing as audio interfaces. They do not connect to your computer and allow you to record to your DAW in the same way that an audio interface does.

So if your interface already contains preamps, why might you choose to buy an additional external mic preamp? Well, aside from boosting the level of a microphone’s signal, mic preamps serve another purpose. They can also impart tonal characteristics into your recording which enhance the sound. As such, you can really upgrade the sound of your recordings by adding an external mic preamp which has a desirable audible characteristic. By contrast, the mic preamps in an audio interface are less likely to impart such a desirable characteristic. Instead, they are more likely to produce a flatter or more neutral sound.

That’s not to say that the mic preamps which are built into an interface will sound bad. Certainly, the higher the quality of audio interface, the better the mic preamps are likely to be. But they’re not likely to be as desirable as a preamp which is purely built for that purpose.

Mic preamps – conclusion:

In conclusion, a mic preamp is a device which lets you boost a mic level signal up to line level. To record a microphone’s signal, you must use a mic preamp. For this reason, your audio interface will have mic preamps built into it. These will be perfectly adequate to let you make good quality recordings. But if you feel like you want to give your recordings somewhat of an upgrade, then you could invest in an external mic preamp which will impart a desirable tonal quality onto your recordings.

Do you use an external mic preamp? Or are you happy to record with your interface’s built in preamps? Leave your thoughts in the comment section below.