Sidechaining in general

In very rough terms, a compressor can be described to consist of two circuits; the level detection circuit and the gain reduction circuit.

The actual compression/gain reduction is dependant on the audio level determined by the detector. Sidechaining is all about giving you control over the signal that enters the detector circuit and ultimately drives the compression. The most common techniques involve either filtering the signal, or assigning a different audio source to control the compression. Common uses for this is de-essing, ducking and synchronized gating which is well known techniques in studios working with hardware compressors, but rarely found in software processors.

"Ducking": If a kick drum gets lost in the mix because of a dominating bass, use this method and let the kick drum control the compression of the bass. This also does a very nice job of "melting a groove" together as a whole. Another use of ducking is on radio style voiceovers; i.e. background music is ducked when a speaker talks and returns to normal level when he pauses.

"Synchronized gating": This technique involves introducing gating in a rhythmic pattern defined by another track. Could be a synth pad being gated to the rhythm of the percussion.

COMPADRE features true stereo sidechaining allowing both external key input and sidechain filtering. And of course you can still switch it off, and use it as a straight ahead compressor.