Mixing Tips Part 2 - Side-Chain Compression
Mixing tips part 2 - Topic: Side-Chain and its applications
What is sidechain compression?
Sidechain compression is a technique that uses the signal from one instrument or voice to trigger a compressor on another signal. The sidechain signal is used to determine the threshold of the compressor and thus to control its effect on the signal to be compressed.
Sidechain compression is often used in music production to control the dynamics of instruments or voices and create interesting sound effects. For example, you can use the sidechain signal of a synthesizer to control the dynamics of a bass instrument and thus create a "pumping" sound. Sidechain compression can also be used to change and shape the sound of vocals or other instruments.
To use sidechain compression, you typically need a compressor with a sidechain function. This feature allows the sidechain signal to trigger the compressor’s threshold, thereby controlling how the compressor affects the signal to be compressed. The compressor’s settings—such as attack, release, and ratio—are then used to shape the desired effect on the compressed signal.
There are many ways to use side-chaining. In addition to the already known techniques, we show a few more examples of what side-chain compression can still be good for.
Just in EDMArea, the pumping effect of a side-chain process has become very modern again. Other terms by which the process is known include New York Compression or Upward compression. Let us now first come to the three most popular possible uses.
How do I set up a sidechain compressor?
To set sidechain compression, there are a few steps to keep in mind:
Choose the compressor with sidechain function: First of all, you have to choose a compressor with sidechain function. This can be either a hardware compressor or a Digital Audio Workstation (DAW) plugin.
Set the signal to compress: Set the signal you want to compress by feeding it to the compressor's input. This can be a bass instrument or a vocal track, for example.
Set the sidechain signal: Set the sidechain signal that will trigger the compressor by connecting it to the compressor's sidechain input. This can be a synthesizer signal or a drum track, for example.
Adjusting the threshold: Adjust the compressor's threshold using the sidechain signal. The threshold determines when the compressor reacts to the signal being compressed and when it stops compressing.
Adjusting Attack and Release Adjust the compressor's attack and release settings to determine how quickly the compressor responds to the signal and how long it compresses. These settings affect the tonal characteristics of the compressor and can be used to create the desired effect on the signal being compressed.
Adjusting Ratio and Make-up Gain: Adjust the compressor's ratio setting to determine how much the signal being compressed is compressed. Then use the Make-up Gain to adjust the volume of the compressed signal and bring it back to the original level.
It is important to take the time to thoroughly understand and test the compressor's settings to achieve the desired effect on the signal being compressed. It can also be helpful to refer to tutorials or other resources for a better understanding of sidechain compression
Sidechain compression used in the bass range
For styles of music that originate "in the box," you can create very dynamic and prominent basses by using side-chain compression. The bass signal is told (using the threshold) that "from this loudness/dynamic value" (depending on whether you are compressing to RMS or peak) the bass signal should be compressed and thus its dynamics limited. This is often used in EDM for the interaction between kick and bassline. The kick is sent as an SC signal to lower the bassline whenever the kick sounds. This way the kick retains its punch and doesn't get lost in the bassline.
Sidechain compression as DeEsser
Everyone knows this useful tool. But what if you don't have a de-esser to hand? Duplicate your vocal track and route it to NO output. This track serves as a "signal generator" for your homemade de-esser. Now, in addition to the compressor, switch an EQ into the audible vocal track and set it so that it works in the range between approx. 7-9 kHz. A ratio of 1:3 is recommended for the compressor. The remaining parameters are a matter of taste and should be adjusted by ear.
Separate or lift passages from one another
Another way to use side-chain is to tell the signal at certain passages that the other signals should be quieter. Using the threshold control, which should be set to (RMS), you tell the compressor to only start working at a certain dynamic value. This is particularly helpful with instruments that have the same frequency range, such as piano and guitar. Using automation, you can give entire signal paths in a chorus more "power", and compress sections of it differently to make room for other instruments or to bring other instruments more to the fore at certain points.
Nested side-chaining
I constructed a 3-way nesting as sidechaining. I did this because, on the one hand, I am playing the kick drum Mix better and on the other hand to construct my own slight "pump effect" between the sine bass and the synth bass in order to create a little more variety within the drum set.
I did this nesting as follows:
Kick drum as a signal generator
Here you can see that the kick serves as a signal generator for the synth bass and the sine bass. I switched the signal level from post-fader to pre-fader. This means that the output signal of the kick is tapped before the volume fader.
Sinus bass as a signal generator
Here the sine bass serves as a signal generator for the parallel compressed synth bass. 
Side chain compressor settings
Here you can see the associated settings for the 3 side chain compressors. 
The settings used here can of course be varied freely, because the following also applies here:
Good is what sounds good and pleases.
It is also possible to "side-chain" effect channels. This is particularly interesting with reverb and delay. You could use a delay signal as a signal generator for a reverb. If you combine this with an attacker on the reverb channel, you can easily create some really crazy effects. There are no limits to creativity here. Have fun with Mixing and mastering.
