What is a Mic Preamp?

What is a Mic Preamp?

At some point you may (or will) come across someone talking about a mic preamp (and usually a heated debate follows). This post deals with what a mic preamp is, what it does and what situations require you to use one. A mic or microphone preamplifier is a device often found in the studio used by sound engineers. The preamp’s job is to ready the signal so that it can be processed by other things. Why is this needed?

A microphone, as you may know, is a transducer. We spoke about dynamic and condenser microphones in another post. 

Most dynamic microphones will only provide a low microvolt range for their out levels which usually is within the 0 to 100 range. The weak signal is hard to process and harder to get into the mixer or for external effects. The preamp can boost this up to 10 volts by increasing levels up to 70 decibels.

In other words, a mic preamp is required to boost a mic’s electronic signal up to the line level. This is necessary to interface with the mixing desk and the 65db to 70db boost that the preamp provides is probably the biggest increase in amplification in an entire audio chain.
A lot of soundcards have in-built preamps which help boost the signal. But keep in mind that these are usually good enough for speech or talking and may not be as useful for vocals.

Mic preamps can be found built-in in most mixing consoles but it may have only one and you may need to plug into a specific input for that. As is the case with soundcards, the quality will depend on the quality of the mixing console and the price you paid for it. In most cases you will need a preamp if you are recording using a PC with just a basic soundcard.

Preamps are capable of giving transparent signals or warming up the sound, depending on the make and the brand/model. Different people find different needs which result in the huge array of products on offer today. There are too many arguments regarding the value addition or the necessity of a preamps and what they do.

These are mostly subjective and the best way to notice what a mic preamp does to the sound is to plug a mic into various preamps and just give it a go. You will notice which ones add noise, which dont, which ones add warmth, which ones add gain and how much and which ones are noisy or quiet.

Today there are more than enough options to choose from in the market. Each of these designs and models promise to provide the consumer with a high quality mic preamp using relative designs which have their own pros and cons.

There are the cheap mic preamps, the tried and tested ones and the expensive tube preamps. You can spend anything from a few hundred dollars to a few thousand dollars to get a mic preamp; it will all boil down to what you need and what you choose. As the old saying goes, nothing is more accurate than your own ears…

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