When to Use Audio Compressors?

There are lots of tools that are used by the audio engineer when he is recording and mixing a song. An audio compressor is one of those tools that are widely used and at times, widely abused. The use of audio compressors in the recording stage has been on the decline since the advent of the audio interfaces and digital audio workstation that support 24bit audio processing.

Using Compressors during Recording

Like I said above, the use and the need for audio compressors when recording has been on the decline. Now days they are used mainly in the mixing and audio mastering stage. Why are compressors on the decline? It is because of audio interfaces having 24bit support. When audio interfaces only had 16bit support, the audio file resolution was lowered by 256 times. This actually means that in 24bit recording, the resolution is 256 more time higher than it would be in 16 bit recording. In return this gives way more headroom and the need for not using a compressor. You can have a peak dB level between -22dB to -12dB and the audio file will be at its optimal levels and sound quality. This can give you up to 22dB's of headroom and that is more than enough room to catch any transient peak that may go above your peak dB level. This is why there is really no need to use audio compressors when you record.

The Main Use for Audio Compressors in Mixing

The main use for compressors in the 21st century are mainly used for mixing and mastering for reasons stated above. Audio engineers mainly use compressors to tame transient peaks and to lower the dynamic range of an audio signal. This in return can make the audio track have more of a punch and can make it stand out in the mix. When mixing, it is ordinary to have compressors on every track. You may say this will leave the mix lifeless and your initial thoughts can be right. But as long as you set the compressors just right, it will give each track in the mix a lot more life. It is key not to overdo the compression of each track. You do not want a pumping effect or a flat lifeless song with no ups and downs to it.

Using Compressors in Mastering

Mastering compressors are used and inserted on the master bus, also know known as the mix bus in some instances. The chain of the effects on the master bus can go like this: EQ, Compressor and Limiter. That is a very basic mastering effects chain. Another chain can be like this: EQ, Compressor, Saturation, EQ, and Limiter. It is good to have an EQ before and after the compressor in the mastering chain. Mastering engineers like to have some frequencies compressed and some frequencies after the compressor. When deciding the order and what to use, you really need to just trust those 2 weird looking things on each side of your head, aka your ears.