Microphone Preamps Explained

A microphone preamp is an essential part of any studio setup in bringing your audio equipment to line level, which is why you probably need one to get everything running properly.

What is a Microphone Preamp?

A microphone preamp amplifies low level signals to line. Bringing audio "to line" is the standard operating level of audio equipment. The two standard line levels are:

• Consumer: -10 dBV (0.316 V RMS).
• Professional: +4 dBu (1.23 V RMS).

Dynamic microphone signals are usually lower then these levels, so a lot of gain is required (20-60dB), which is why you need a microphone preamp like an audio interface in order to your mic working. Powerful condenser and dynamic mics, like the ElectroVoice RE320, need around 12-48v DC (aka phantom power) in order to work properly. Without it, audio captured would sound faint or not present at all.

When You Need a Microphone Preamp

Professional studios use microphone preamps. If you use a condenser microphone, then you're probably going to need to bring it to line level with a preamp. External preamps and audio interfaces mainly do 3 things:

1. Gives your mic better sound quality.
2. Add more gain to amplify the signal.
3. Removes low level noises.

Most microphones or other audio equipment usually state if you need to bring it to line level (or the actual dB so you can work it out yourself). If in doubt, contact your manufacturer and see what they suggest.

Will an Audio Interface Work?

Modern audio interfaces come with a microphone preamp built in and offer a 48v option for phantom power. For example, the Focusrite Scarlett 2i2 offers this for two microphones, with the option to switch 48v on or off.

Alternatively, if you don't have an audio interface you can use an external preamp like Simply Sound’s SS-1. It acts as a way to boost your mic's line level and offers noise free amplification so you can’t hear as much background sounds like noisy floorboards or outside chatter.

However, preamps like this usually go to a certain level, (in this case that's 27dB), require 48v to work, and might not work with condenser mics (the SS-1 is for dynamic mics). Always check the manufacturers website for more details, but if in doubt then stick with an audio interface or a device that guarantees 48v like the Shure X2U XLR to USB adapter (which is perfect to plug directly into your computer or laptop).

Navigating the world of audio equipment can be confusing at times, that's why the team at Radio.co is here to help. If you're not sure if your microphone needs a preamp then get in touch. Talk to an expert about your radio station and ask for advice on audio equipment. Book a demo to speak to one of our professionals today.

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