Fun with Compression

Fun with Compression

Compression is a workhorse tool that is crucial to modern recording, yet rarely acknowledged by the clamoring masses.  There is a sexier way to use it though that’s worthy of more attention and it’s called sidechain compression.  Sidechain compression involves using a secondary signal to trigger a compressor that’s affecting another element.  This may seem like a weird thing to do,but it can be a very effective tool.  

The most common use of sidechaining is to duck (reduce the volume of) a signal every time another element plays by using the sidechain on your compressor. A good example of this would be to feed a copy of the kick signal into a compressor on your bass signal which then ducks the bass every time the kick is hit.

With subtle settings on your compressor this will result in a slight ducking of the bass which allows the kick to cut through the mix better.  This is cool, but you can get a more exciting effect by digging in a little bit more on the compressor. By increasing the ratio or lowering the threshold the ducking will become more drastic. This will create a noticeable dip in the bass signal and a pumping effect as the compressor releases the signal and it returns to its normal volume.  By playing around with your release time you can get the pumping to happen in time with the track which adds a lot of excitement. This effect is used extensively in dance music where  any rhythmic and harmonic element may be used..  

Another trick, is to create a rhythmic element that isn’t represented in the track as the sidechain input.  If I go back to our original example of kick and bass, I create a kick track whose output goes directly to the sidechain input (also known as the key input) of the compressor on the bass.  This allows me to have the bass pumping in a way that may be counter to my original kick pattern or to have it pumping even if the kick isn’t playing in the mix at the same time.

I’ve barely scratched the surface of what you can do with sidechaining here, but you can see that the possibilities are endless.  It can be used to duck unwieldy effects while an instrument is playing or to get cool filtering effects by utilizing a multi-band compressor.  I suggest setting aside some time and exploring the possibilities!