What Is Sidechaining? Here’s An Overview

Sidechaining is an audio production technique where the output of one audio signal is used to activate and control an effect on another. It is commonly used with compression to give instruments more presence in the mix.

row of dynamic microphones

This production technique will substantially improve the quality of your music when used appropriately.

Inside this article:

What is Sidechaining?

Sidechaining works as follows: If an audio signal is coming from track A, activate effect X on track B.

Here’s an example…

If the kick is playing, activate compression on the bass guitar.

Sidechaining in this matter is a form of automated compression that only occurs when there is input from another track in the mix. The compressed instrument is automatically moved to the background so another can shine through (this is called “ducking”).

Here’s what that looks like graphically:

diagram of how sidechain compression works with a bass and kick

This can make a huge difference to your mix. Check out the example in this video put together by iZotope:

As a producer, you will find many applications for sidechain compression. You can apply it to drums, vocals, synths, and more.

The Origins of Sidechaining

Sidechaining was invented in the 1930s to take “S” sounds out of spoken word in film. Eventually, broadcasters came to realize that sidechaining could automatically reduce the volume of background music when a presenter spoke. After this discovery live TV broadcasts, DJs on the radio, and even grocery store announcements made use of sidechaining (which meant a technician didn’t have to turn down the volume every time someone spoke).

Sidechaining become popular in music in the 80s and 90s after it became standard for studio equipment to have the functionality built-in.

One of the first genres to go all-in on sidechaining was electronic music. For club and dance music it is essential the kick shines through the mix, however multiple layered synths and pads have a tendency to drown out the bass. For old school electronic music producers this meant they had to balance between complexity and maintaining the power of the low end.

Sidechaining changed the game by allowing electronic music producers to use as many synths as they wanted. They simply had to apply sidechain and the kick would shine through.

Daft Punk’s “One More Time” heavily features sidechaining in the chorus:

Today sidechaining is used prolifically in EDM. It has also found its way into a multitude of other genres, including hip hop and pop.

Sidechaining the Kick and Bass

By applying sidechain compression to the bassline your goal is to make the kick shine through the mix. If you’ve already tweaked the faders and cut some of the competing frequencies through the EQ process, then it’s time to apply sidechain compression.

See if you can hear the difference between these two examples.

Sidechaining disabled:

 
Sidechaining enabled:

Enabling sidechain pushes the bass down every time the kick hits.

You can control the amount the bass is pushed down via the compressor – more aggressive compression will create a more extreme sidechain effect. Most of the time sidechain should be subtle, but not always…

Creating the “Pumping” Effect

You might have heard the term “pumping” before. Pumping is what happens when the kick and bass are sidechained and compression is applied very aggressively. You’re pumping when the bass is clearly dropping in volume each time the kick hits (as opposed to a slight decrease that serves to increase clarity).

So why would you want to do this? Well, it creates a neat effect that really drives the kick.

You can clearly hear pumping in “To The Floor” by Minnesota:

To achieve a pumping effect, use an extremely high ratio, a hard knee, and a low threshold in your compressor. Make sure your attack and release are very fast too.

How aggressive should your pumping be? That’s up to you. If you’re putting together the next EDM hit it’s safe to say you can be rather aggressive, but otherwise consider scaling it back a bit by allowing for a longer release and setting the threshold a few dB louder.

Sidechaining Vocals, Drum Kits, Pads, and More

As a producer you can do much more than sidechain the kick and bass.

You can also sidechain snares, pads, vocals, and really anything else. Here are a few ideas:

Sidechaining vocals

Place a subtle amount of sidechain compression on guitars, synths, pads, and other instruments that compete with vocal frequencies to give the voice track(s) additional presence.

To sidechain vocals, set a low ratio of 2:1 or 3:1 and lower the threshold until you start to see a small amount of gain reduction. Use a fast attack and release to keep the effect subtle.

If you want to be a superhero you can use a multiband compressor with sidechain functionality (like FabFilter’s Pro-MB) and apply compression to only the audio frequency range that the vocals sit in. This will allow you to increase vocal presence without impacting the lows or highs of your song.

Dampen reverb & delay effects

Reverb and delay are effects that can quickly overpower the mix and are tough to balance. Applying sidechain can help.

With delay you can sidechain the lead instrument to the delay track so it is compressed whenever the lead instrument is playing. Placing a compressor on the reverb channel and sidechaining this to your kick and snare will help eliminate overbearing reverb.

Sidechaining multiple tracks together

You can sidechain more than one track to another.

You can sidechain your snare, bass, leads, and any combination of other instruments to a given track. The only limit here is your own creativity.

Make room for effects and highlights

Sidechaining is a great way to make effects, guitar solos, and other highlights stand out.

Sidechaining can do amazing things to your mix so be sure to play around with this technique!