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What's the Best Microphone Preamp for Me?

What's the Best Microphone Preamp for Me?

You’ll find them in most home and professional recording studios: microphone preamps. But when should you use a mic preamp and what should you look for when choosing the right one for you? In this Buyer’s Guide, we answer some of the most common questions regarding microphone preamps. If you can’t find the answer to your question here, feel free to contact us!

1. What’s a Microphone Preamp?

Microphone preamps often come built into mixing consoles, audio interfaces and recorders, they’re also available as stand-alone units. The goal of these preamps is to ‘prepare’ microphone signals to be recorded. Microphones convert sound waves (vibrating air) into an electrical signal of just a few millivolts. To be able to edit and mix this signal, it first needs to be amplified, and that’s where the microphone preamp comes in. Just how strongly any mic signal is amplified depends on the gain.

Microphone Preamps

2. What’s the Difference Between a Preamplifier and an Amplifier?

A preamp converts microphone or instrument signals of a few millivolts to a 1 Volt level, commonly known as line level. Line level signals can be recorded using a recorder or DAW software, and are used by effect-based equipment such as equalisers, compressors, reverbs, etc. In order to play back a line level signal using a pair of speakers, it needs to be amplified with a ‘standard’ amplifier. Preamps simply aren’t powerful enough for this.

Tip: If you’re looking for a complete, plug-and-play system to amplify vocals or speech for live performances, have a look out at our Portable Battery-Powered Speakers and Active Full-Range Speakers. These speaker systems often feature a built-in microphone preamp that serves as a power amp. For more information, you can check out our Speaker Buyer’s Guide.

Microphone Preamps
Amplifiers
Portable Battery-Powered Speakers
Active Full-Range Speakers
Speaker Buyer’s Guide

3. Do I Need a Microphone Preamp?

One or more microphone preamps often come built into mixing consoles, audio interfaces and recorders, so you won’t need to hook up one up to one of these devices. You will need a separate microphone preamp in any of the following situations:

You want to connect a microphone to a device that only has line inputs.
The built-in preamps aren’t powerful enough (e.g. when you have a ribbon microphone, since these require a lot of gain).
You want to expand the number of inputs of your audio interface.
You want to change the timbre of the sound (e.g. when you want to get the sound of a tube amplifier).

Microphone Preamps
Microphone Preamps with Tubes
Mixing Consoles
Audio Interfaces

4. Do Stand-Alone Preamps Sound Different?

Preamps like the ones built into mixers are designed to amplify sound as ‘cleanly’ as possible, but when you’re recording music, it may be that you prefer to add a little ‘colour’ to the sound to give it, say, a warmer character. Preamps outfitted with valve and/or transformers can offer an especially wide range of colour and character by adding more, or less overdrive. This means that any peaks are carefully rounded off, which in turn gives you a lightly saturated sound. This limited amount of overdrive isn’t harmful for the preamp, and to make sure any gear further up the audio-chain (e.g. converters) aren’t overdriven, stand-alone preamps are often equipped with a separate output control so you can attenuate the signal again. Also, it’s worth noting that overdriving any built-in preamps is pointless, since instead of enhancing the sound musically, it would only downgrade it. On top of that, in the case of audio interfaces, overdriving the signal would only clip the A/D converters and give you the kind of distortion that you don’t want.

Microphone Preamps with Tubes
Microphone Preamps
Mixing Consoles
Audio Interfaces

5. Can I Expand My Audio Interface with a Microphone Preamp?

Yes, as long as your interface is equipped with digital inputs (e.g. ADAT) and the microphone preamp has a matching digital output, you can add a number of fully-fledged inputs to your interface in one go. Any additional inputs will even ve given their own tracks within any DAW software and, thanks to the digital signal transfer, there’s zero loss of audio quality.

It may also be that your audio interface has a given number of line inputs. Normally, you wouldn’t be able to connect these to microphones, but what you can do is connect a microphone to an external preamp and then connect the outputs of the preamp to the line input of an audio interface.

Tip: When browsing through our Audio Interfaces, you can use the filters to only see interfaces that include digital inputs.

Microphone Preamps with Digital Inputs
Microphone Preamps
Audio Interfaces

6. Is It Possible to Connect an Instrument to a Microphone Preamp?

It’s not only possible, it can actually be a good idea to hook your guitar or bass up to a microphone preamp. The valves and transformers can beautifully enhance the sound of your instruments, but you need to bear in in mind that Hi-Z (high-impedance) instruments can only be connected if the preamp is fitted with a special instrument input, or if the microphone input features an input impedance switch that says ‘Hi-Z’ or ‘Instr’. Next to an XLR input, such a preamp will also have a jack input. If the preamp doesn’t have any of this, it’s possible to use a DI box to adjust the impedance. Please note that instruments with a line output, including keyboards and digital pianos, send out a signal that’s many times louder than any microphone preamp can handle. These instruments can still be hooked up to the microphone inputs, just don’t forget to seriously lower their output level! Tip: When browsing through our Microphone Preamps, you can use the filters to only see interfaces that include specific inputs.

Microphone Preamps
DI Boxes

7. What Other Functions Can Microphone Preamps Offer?

Phantom power / 48V: This is for powering condenser microphones. When phantom power is active, the microphone is simply powered via the connected XLR cable.
Phase switch: Reverses the phase from positive to negative; useful when you’re using multiple microphones where the signals work against each other.
Low cut: Takes out the very lowest frequencies; useful when you’re recording something like vocals and need to get rid of any unwanted lows. Also helps to keep ambient noise (e.g. street noise) out of the recording.

Preamps featuring one of the following functions are commonly referred to as channel strips:

Equaliser: Used to tweak the sound by boosting or attenuating certain frequencies.
Compressor: Used to limit the dynamic range of the signal and make any quieter parts easier to hear.
Gate/Expander: Used to remove unwanted noise. Any sound below a set threshold is cut out.
De-esser: Used to soften the harder ‘S’ sounds of vocal recordings. A de-esser is basically a compressor designed for the higher frequencies.

Microphone Preamps
Microphone Preamps with Phantom Power
Microphone Preamps with Phase Switch
Microphone Preamps with Equaliser
Microphone Preamps with Compressor
Microphone Channel Strips

Links & More Information

Blogs & Buyer’s Guides

Recording and Amplifying Vocals for Beginners
Compression: What is it and How Do You Use it?

Speech / Vocal Microphone Buyer's Guide
Studio Microphone Buyer's Guide
Audio Interface Buyer's Guide