Microphone preamp

A microphone preamp is the first amplification stage a mic's signal passes through, boosting a naturally weak electrical signal, especially from a dynamic microphone, up to a level strong enough for the rest of the audio chain to work with cleanly. Every audio interface and mixer has a preamp built into each input channel.

Preamp quality is judged mainly by how much clean gain it can provide before adding noticeable hiss or noise, and by how flat and neutral it keeps the tone across that gain range. A weak preamp paired with a low-output dynamic mic is one of the most common reasons a recording sounds thin or noisy even with careful gain staging.

Standalone preamps also exist as separate boxes for podcasters who want more gain or channels than their interface's built-in preamps provide, feeding a cleaner, stronger signal into the interface's line input afterward. For most home studios, though, matching a mic's output level to an interface with adequate built-in preamp gain is simpler and usually sufficient without adding another box to the signal chain.