Sidechain compression is a cool mixing technique that’s all the rage these days. In this article, we’ll break down the basics of sidechain compression and show you how to use it to make your mixes sound awesome.
Compression can be tricky when you’re new to mixing, but it’s a powerful tool that can make your mix really stand out. One cool way to use compression is with sidechain compression. Sidechain compression is like a secret weapon that works by comparing the volume of two (or more!) tracks. When one track gets louder, the other gets quieter. How does it do that?
What is sidechain compression?
Sidechain compression is like having a secret weapon in music production. It’s when one instrument or sound acts as a boss, telling another sound how loud to be. Imagine the second track, like a sidekick, sending a signal to the first track. The first track then responds by getting quieter when the second track is active. It’s like having a volume control built into your music!
What is the sidechain?
Imagine the sidechain as the boss of a compressor. It’s like a boss that tells the compressor how to react to the sound it’s hearing.
Compressors are used to make the louder and quieter parts of a sound sound more similar in volume. This can be done to an instrument, a loop, or even an entire mix.
The term “sidechain” comes from the phrase “side signal chain.” “Side” means different from the main input source (like the sound you’re compressing). “Signal chain” means gear that processes an audio signal, like an equalizer.
Interestingly, the first use of sidechain compression involved an equalizer.
Using sidechain compression for practical purposes
Sidechain compression, also known as ducking, is a handy audio effect that can be used in various ways. Imagine you have a bass track that’s competing with the kick drum for volume. Sidechain compression can help balance things out by reducing the bass’s volume whenever the kick drum plays. This technique is particularly useful in electronic dance music (EDM).
In radio and podcasting, sidechain compression can be employed to lower the volume of a dialogue track whenever the other person speaks. It can also be used to reduce the volume of the theme music track when the host starts talking.
Typically, sidechains are found on dynamics processors like compressors, gates, and dynamic EQs. However, there may be exceptions. So, if you’re looking for audio effects that use sidechain compression, focus on threshold-based effects.
Here are some additional ways sidechain compression can be used in mixing:
* Drum Overheads with Overwhelming Snare: Compress the drum overheads and send the snare (close mic) to its sidechain. Whenever the close-miked snare plays, the snare-heavy overheads will be reduced in volume.
* Bright Guitars Covering Up the Lead Vocal: Insert a dynamic EQ or multiband compressor on the offending guitars. Set it to subtly reduce or compress the frequency range where the vocal is present and bright. Then, send the vocal to the sidechain! Whenever the vocal is heard, the guitars will get a bit “mellower.”
* Excessive Bleed in the Kick Out: Put a gate on the “Kick Out” track. Assuming that the “Kick In” track doesn’t have excessive bleed, send it to the gate’s sidechain. Now, the kick track without bleed controls the gate on the bleed-heavy kick. The bleed in the “Kick Out” won’t open the gate!
Sidechaining for creative purposes
Sidechaining can also be used in creative ways such as on the intro piano of “Everything I Wanted” by Billie Eilish. Notice how we perceive a beat even though there is no audible kick drum until about 40 seconds into the video.
This is because the kick track is sidechained to the sustained piano track. The kick drum’s signal is triggering the compressor to lower the volume of the piano each time the kick hits. This gives us the sensation of a beat before it actually kicks in.
The history of sidechain compression
Meet Douglas Shearer, a cinema sound designer with a unique idea. He wanted to make the spoken dialogue in movies quieter when actors said sibilant words. But guess what? De-essers, the tools that could do this, didn’t exist yet.
So, Shearer got creative and invented one himself. He split the audio signal into two paths. One went through a compressor, while the other went to an equalizer. With the equalizer, Shearer filtered the signal until only the most annoying ess sounds remained.
Then, he sent this signal to the compressor’s detector. The compressor “heard” only the harshest sibilant sounds and then “processed” the main dialogue signal. The result? The compressor only reduced the volume when it detected harsh sibilant sounds.
This is the power of a sidechain. The sidechain controls the compressor in specific ways, with very specific rules. And the compressor follows these rules to the letter.
In the case of a de-esser, the rules are based on frequency. The sidechain says, “only compress when you hear this super harsh frequency range,” and the compressor says, “yes, sir!”
Start using sidechain compression
Sidechain compression is a valuable process to learn. It’s one of the most frequently used techniques in modern mixing, but beyond that, it really lets you do great work.
Now that you know a few different applications for sidechain compression and how to set it up in your session, feel free to experiment with it in your mixes. Use it to manage low-end energy between kick and bass or glue a couple of other tracks together in interesting ways. Anything can be sidechained to anything, so don’t be afraid to experiment!
