What is Sidechain EQ and How to Use It

Similar to sidechain compression, sidechain EQ uses a different track’s dynamic level to affect another track’s behavior. The effect is very similar to sidechain compression, but it allows you to be more surgical and can yield more transparent results. Let’s talk what is sidechain EQ and how to use it in your mix.

What is Sidechain EQ

Sidechain EQ pulls down the volume of a track based on the dynamic volume/level of a different track, but that volume attenuation is applied to a specific frequency range rather than the entire track.

It does this using dynamic EQ, meaning the cut/boost of a frequency band isn’t uniform or static but changes depending on that aforementioned volume of the other track.

This differs from sidechain compression which affects the entire track’s volume. In the case of sidechain EQ, we can specifically pull out only the low, mid, or high frequencies at a changing pace, leaving the rest of the frequencies of the track unaffected.

The benefit of sidechain EQ is that it can yield more transparent results over compression.

How to Use Sidechain EQ

Now that we’ve answered what is sidechain EQ, let’s talk about how to use it.

I’ll reference my most common application of sidechain EQ which is controlling the low end of the bass using the kick.

Before I get into it, let me note that not all EQs allow for sidechain capabilities built in. I did a specific tutorial on sidechain EQ in Ableton recently using their stock EQ which does NOT feature this ability inherently (it requires an extra step as I show in the link).

I do my sidechain EQing using FabFilter’s Pro-Q 3 as it’s incredibly easy to do, not to mention it’s my favorite EQ/arguably plugin in general (see my FabFilter Pro-Q 3 review.

Getting back to how to use sidechain EQ, specifically to control the sub bass frequencies of our bass, we need to first drop an instance of FabFilter’s Pro-Q 3 on our bass and create a bell filter around 60Hz.

This is typically where the fundamental fatness of the kick resides (see how to EQ kick drum), but you can check your kick by soloing around here and listening where it’s the loudest.

We want to use the sidechain EQ to pull this frequency range out of the bass when the kick triggers. For that split second it gives the kick free reign and control of that frequency, cleaning up the low end of the mix and giving the kick presence.

Once we have that bell filter created, we tell the plugin to use its sidechain feature, getting audio from our kick track and designating where in the signal chain it should pull that audio (see post mixer vs pre mixer).

Now we just need to click the sidechain button on that filter in Pro-Q 3, adjust the threshold, and adjust the dynamic gain range until we have the attenuation we want when that kick activates:

I like to average about 5-10dB in gain reduction at that 60Hz range/fundamental of the kick on the bass. This leaves the higher end of your bass untouched so those transients can still cut through (see my bass EQ cheat sheet) while still clearing up the low end for those split seconds when the kick is playing and needs dominion over that space.

When you don’t need to get surgical, sidechain compression still works just fine, but sidechain EQ is ideal when you need just a specific frequency range to get out of the way of another track like the case with the center “panned” bass and kick.