Improve Your Sidechain Compression Skills

If you're into electronic music production, you've probably heard "sidechain compression" more than once. For those unfamiliar, sidechain compression means using the output of a track, such as a kick drum, to trigger the compression on another track, such as a bassline.

Assume you're watching a movie, and there's a scene with no dialogue or sound effects. Here, the soundtrack can be blasting. However, as soon as the dialogue comes back, the music needs to duck down to allow for the intelligibility of the speech. You can achieve this in real-time on your mix by using sidechain compression.

Many producers use tools that cause the entirety of an audio signal to be sidechained. As a result, the whole frequency spectrum of the audio becomes ducked. In our case, we'll show you an alternative enabling you to sidechain only specific frequencies.

As usual, we have prepared a short sequence in our SoundBridge: DAW. It contains most elements of a full mix without the sub-bass. Let's take a listen.

As mentioned, this sequence lacks the sub-bass. This sound will be the perfect example to demonstrate the sidechain compression technique. After writing a simple MIDI sequence for the sub-bass, let's hear it unprocessed together with the kick drum.

From the audio example above, we can hear that the sub-bass clashes a lot with the low frequencies of the kick drum. Instead of traditional sidechain compression, where the whole signal gets ducked, we will use a technique to preserve our sub-bass sound's dynamics and tone.

We will do this with the help of FabFilter Pro-Q 3. Let's drag an instance of it to the sub-bass channel effect rack. In order for sidechain compression to be triggered by anything, we will have to enter the menu for it inside the SoundBridge effect rack. The picture below shows the corresponding "S" icon on the FabFilter Pro-Q 3 effect. This icon represents the sidechain setting. Once clicked, it takes us to a menu where we can choose what actually will trigger the sidechain. As you can see, we have selected the kick drum as a trigger.

If we look at the picture below, we can see there are now two analyzer images in the FabFilter interface. The grey one represents the sub-bass signal, and the red represents the kick drum. We can set this in the "Analyzer" section below. This helps determine where exactly the two signals clash. In this case, the area is between 20 and 50 Hz.

In order to apply sidechain compression on just this particular area, we will add a new EQ band, and by right-clicking on the created frequency point, select "Make Dynamic."

At this point, the triggering is still not occurring. Instead, the compression is independent of the kick drum and reacts on the sub-bass.

In order to fix that, we will have to enter another menu by clicking on the "AUTO" icon above the "Gain" knob.

Next, we have to click on the small icon next to the Band 1 Threshold fader, which will engage the sidechain trigger.

We will set the threshold level to our liking, and that's pretty much it! Let's listen to the difference now.

You can use this technique for anything, not just kick and bass.

Let's hear our full mix with the sub-bass processed.