Looking at a mixer you notice there are several strips with identical buttons on each strip. A microphone preamplifier is basically a stand alone mixer strip. When you buy a recording console you are pretty much committed to the sound quality of each strip because they are all the same. That is where a microphone preamp comes in. A microphone preamps main duty is to boost a microphones low signal to a line level that is usable for any device you are recording too. There are plenty of variety, design, features and sound quality that allow you to mix and match different pre-amps for your recordings.
There are a few common features among most microphone preamps. Gain control allows you to adjust the signal being picked up by the microphone, however too much gain can create noise in your recordings but can be helpful when recording quiet performances. Another feature that can be found on microphone preamplifers is an equalizer (EQ), which can cut or boost a given frequency to change the sound quality of an instrument. Just a helpful hint, when doing your mixing try to cut frequencies first before trying to boost frequencies.
A compressor is another feature found on some preamps. Compression squishes the dynamic range of a signal, then boosts that signal so that the quiet parts of a recording is louder. Now during a loud part of a song you can still hear the quiet acoustic guitar for example. Be careful because once you use compression on your dry recording you are committed to that compression. It is very hard to remove compression once you are editing.
In the digital realm microphone preamps are very useful. Instead of having a bigger recording console you can have a couple unique microphone preamps, which can conveniently be connected to an audio interface or sound card with line inputs.Choosing a microphone preamp is purely a personal choice and what choice you make is purely what will work best for you. Microphone preamplifiers are a very cost effective way of experimenting, allowing greater functionality and adaptability in your studio.
Sometimes you will find yourself in a critical situation and a microphone preamp can offer low distortion specs, a special sound, or use of tube and integrated circuit technology, which is why microphone preamps are used. When it comes to the selection of a microphone preamp it is purely a personal choice. The days where there was only a few ways to get a great recording is gone, now you can choose from an abundance of equipment. It is important to try and test microphone preamps to find the one that will do the job you want and have people wanting to record with you because you have that preamp that records the sound they want.