THE PRO PRODUCER’S GUIDE TO SIDECHAINING

Sidechain compression is the process of using an external signal to trigger the threshold of a compressor. The rise in the popularity of French house in the noughties thrust the technique into the spotlight, and you can clearly hear the effect being used in tracks such as Eric Prydz’s classic track Call On Me: the music and vocal drop in volume when the keying signal (in Prydz’s case, the kick drum) plays, creating a pumping effect that not only gives the kick more room to be heard but psychoacoustically tricks us into thinking it’s louder than it actually is. In truth, sidechain compression is actually quite an old sound engineering technique, and one that’s not generally used to quite such extreme effect as in Call On Me. For example, it’s frequently used in radio to lower the volume of the music when the DJ speaks, helping to maintain a consistent volume level and making the DJ easier to hear.

We can use the same idea to prioritize sounds in our mixes, and this is especially important when we have sounds that occupy the same region of the frequency spectrum. By deciding which of the sounds is less important, we can temporarily lower or ‘duck’ its volume, allowing the more important noise to be heard clearly.

It’s possible to achieve this ducking effect in a number of ways, of which sidechain compression is just one. We can lower the volume of elements by automating their gain, use volume modulation effects, or