Why You Need a Microphone Preamplifier

A microphone preamplifier is an essential part of any studio setup. Here's why you might need one to get your mic running properly.

Jim Cretney
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A microphone preamplifier is an essential part of any studio setup. If you're broadcasting from a radio station, running a podcast, or even have a music rig, you need to make sure your equipment is at line level. Here's why you might need a mic preamplifier to get your audio equipment running properly.

What is a Microphone Preamplifier?

A microphone preamplifier, or mic preamp for short, is to amplify low level signals to line. 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.

Bringing audio "to line" is the standard operating level of broadcasting and recording 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 way below these levels, so a lot of gain is required, usually around 20-60dB, which is why you need a microphone preamplifier or audio interface in order to get your mic working.

When You Need a Microphone Preamplifier

Most professional studios use a microphone preamplifier. 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 have 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 toggle 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 specifically 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 we're here to help. What type of microphone are you currently using? If you're not sure if it needs a microphone preamplifier then let us know in the comments! Alternatively, if you're thinking of starting a radio station and want advice on audio equipment, then speak to one of our professionals by booking a demo.

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