Sidechaining is a technique for controlling the level for an effect whenever another sound is playing. It is like creating an automation clip that is the exact shape of an audio track. You can think of it as a real-time automation clip. The amplitude of an audio becomes the modulator that controls the level.
A common example is sidechaining the bass compressor to the kick drum. This causes the compressor to activate whenever the kick is played, making the bass quieter. This helps avoid clashing between the kick and bass by ducking the bass out for a moment while the kick plays.
In Logic Pro X
Add your compressor to the track and in the top right, choose the source for sidechain. For example, add the compressor to your bass instrument, and set the sidechain to be the kick. Then you’ll see the compress needle move and activate whenever the kick is played.
To give it a longer breathing effect, increase the Ratio on the compressor to really squash the bass down to almost nothing, and then increase the Release to get a slower breathing effect on the bass line. Also play with the Threshold to taste.
In FL Studio
In FL Studio, there is an extra step. First, you need to sidechain the track in the mixer.
After you have sidechained in the mixer, add Fruity Limiter and in the compressor section, choose the sidechain. Play with the Threshold, Ratio, and Release to control the shape.
You can fake a sidechain by using envelopes to control volume. In FL Studio there is a great plugin called Gross Beat. A clone is also available named MRhythmizer. It contains a preset for sidechaining that creates the pulsating breathing effect on a bass like. You can do similar with any other envelope controller like LFO Tool or Fruity Envelope Controller.
You should now have a basic understanding of sidechaining and its most common use case with kick and bass. You can also use this technique in other creative ways. Try experimenting with:
- Using vocals to control reverb
- Having an EQ on one instrument change shape when another instrument is playing
- Using a track to trigger a noise gate