Side chaining is a process where you link an audio trigger to an effect. The most popular one would be side chain compression. What ever the effect it still works the same.

Basically how it works is a signal from outside the effect, that isn’t part of the sound you are manipulating, triggers the effect it’s self. For example, referring to side chain compression, a common thing people will do is have a compressor on there bass and use the kick drum in there track as a trigger for the compressor. So rather then the compressor reacting to the bass and its transients, the compressor will only compress the sound when the kick drum hits. The use of side chaining in this instance is for volume ducking. If the bass covers the frequencies that the kick is hitting then that area of the sound spectrum may get too crowded, especially in hard hitting dance music as the kick and bass both have to have a big presence in the mix, and if there are a lot of frequencies from the main bulk of both elements in the same place then they will interfere with each other and take away/add characteristics to the sound in that frequency range. This isn’t always bad if they resonate well, but this isn’t always the case, lets say for this example that they don’t resonate well together so we want to “duck” or lower the volume of the bass every time the kick hits to make space for both.

This is a kick with a baseline underneath …
[SOUNDCLOUD]http://soundcloud.com/the-real-daftfader/sidechaining-explained-01[/SOUNDCLOUD]

Here I’m using side chain compression to duck the volume of the sub every time the kick hits …
[SOUNDCLOUD]http://soundcloud.com/the-real-daftfader/sidechaining-explained-02[/SOUNDCLOUD]

And this is the bass with the side chaining on it’s own so you can hear what it does to the bass …
[SOUNDCLOUD]http://soundcloud.com/the-real-daftfader/sidechaining-explained-03[/SOUNDCLOUD]

You can hear the bass ducking every time the kick hits and the bass also has a nice bouncy effect to it. Depending on what you are wanting to do the ducking would be more subtle normally, I’ve just over emphasized it so you can hear it, but normally it’s barely audible, but it cleans things up and makes them fit better. If of course you are trying to achieve that pumping of the bass then you would compress the bass more as the kick hits. This method can also be used to get effects on synth lines.

Here’s a synth and a kick …
[SOUNDCLOUD]http://soundcloud.com/the-real-daftfader/sidechaining-explained-04[/SOUNDCLOUD]

With side chaining used as an effect …
[SOUNDCLOUD]http://soundcloud.com/the-real-daftfader/sidechaining-explained-05[/SOUNDCLOUD]

And the synth on it’s own …
[SOUNDCLOUD]http://soundcloud.com/the-real-daftfader/sidechaining-explained-06[/SOUNDCLOUD]

You’ll probably recognize this effect from a lot of trance tunes. 😉

Side chaining can also be used for lfo’s, for example you can have one lfo effecting a sound, and another lfo effecting the amp of the first lfo. So every time the second lfo is at it’s peak the first lfo is effecting the sound the least.