In any recording situation, you’ll need to bring a microphone up to a useable recording level, without increasing the noise. Microphone preamps are used to increase the gain of the signal, but can also provide phantom power and influence the tone. They’re included on all audio interfaces, but there are also standalone preamps available at budget and professional price points.
ART TubeMP is a good place to start. This preamp is a standalone unit that is not rack mountable. It features separate input and output gain as well as other features such as a gain boost, phantom power, and phase reverse. Though this preamp works great in most circumstances, we’ve found the +20 dB gain boost can add a considerable amount of noise to the signal and is basically unusable at best.
Behringer Tube Ultragain MIC200is also a 1 channel tube preamp. It features separate input and output gain, a 20 dB pad, 48 V phantom power, low cut and phase reverse. This preamp can also be used to tweak your tone. The Behringer MIC200 has a preamp voice control that can be set to different instruments such as voice guitar, bass, etc.
Nady PRA-8 might be the solution for you. This unit features 8 individual preamps with separate gain control and phantom power, as well as a peak gain indicator for each channel. The unit is rackmountable, which is helpful as you expand your studio and purchase more gear.
Though this unit’s sound quality might not be as good as some of the others, it will be able to cleanly boost 8 microphones signals and is likely one of the cheapest options available. The Nady PRA-8 Mic Preamp is great if you have an audio interface with more inputs than outputs, but it doesn’t feature an optical out, so it relies on other line inputs to be picked up by the audio interface.
Presonus TubePre v2 provides professional quality processing at the price of a single preamp. With separate Drive and Gain controls, you can easily adjust your levels without increasing the noise.
The PreSonus TubePre V2 also features polarity reverse and phantom power. A high pass filter can also be enabled, which cuts out frequencies below 80 Hz. This is great when recording an electric guitar, since these frequencies typically interfere with the bass and cause low end problems during mixing.
This preamp features both XLR and ¼” inputs on the back, so it can be used with either a microphone or directly with a guitar or bass. There is an instrument switch on the front that allows the PreSonus preamp to also act as a direct box.