Sidechaining in mixing terms has a number of uses both practical and aesthetic for a bit of ear candy, depending on how it’s applied. Let’s identify what is sidechaining and more importantly talk how to use sidechaining in mixing like the pros.
What is Sidechaining
Sidechaining in the context of mixing refers to controlling some kind of processing/plugin on one track based on the behavior of another track in your mix.
This can be applied to virtually any type of processing with the most common example of sidechaining being compression.
Really any parameter which can be controlled can be used with sidechaining, but the best way to describe what sidechaining is is through demonstrating how to use it in your mix.
Arguably the most classic example of how to use sidechaining in mixing which I’ve referenced and detailed on this site time and time again: sidechain compressing your bass to your kick drum.
As I detailed in my low end mixing tutorial, the kick and bass in your mix share similar fundamental frequencies.
In other words, that low end body which is the “thud” of your kick drum exists in the same frequency as the lower end of your bass.
One of the keys to achieving a more professional sounding, clean mix is to keep tracks which share similar fundamentals as far apart as possible. This is managed chiefly through stereo panning and to a lesser extent through leveraging the third dimension of your mix that is depth with tools like reverb.
This isn’t always an option when two tracks have to share the same spot in the stereo field, like the kick and bass which sound best when centered in the mix.
They are both essential elements to the rhythm and metaphorical backbone of the song, so they need to be consistent regardless of where someone’s listening to the mix in relation to the stereo field which can only happen when they’re centered.
The solution is to use sidechaining to duck that bass out for the relatively short instances when the kick triggers and plays.
As mentioned, sidechain compression is a solution here to compress the bass to pull down its volume relative to the kick exclusively when the kick plays. This is a relatively transparent way to get the two elements to work together; the kick gets complete uncompromised access to the low end when it needs it, and the bass is only pulled down for a few milliseconds and only when the kick plays.
How to Use Sidechaining in Mixing
Taken from my overview on what is sidechain compression, this graphic shows how to use sidechaining in mixing with the aforementioned example:
You simply drop your compressor of choice on your bass track. I like to put it late if not at the end of the processing chain for the bass (see how to mix bass for my complete bass processing chain, by the way). This ensures that the bass is still receiving all of the other processing and sounds as you designed it when it’s being ducked out.
The most important part of this process is actually setting the compressor to observe the sidechaining and designating the sidechain source. Different DAWs approach this in different ways; in my Ableton Live it’s just about ticking the wrench icon to access the sidechain panel, selecting your source (in this case our kick track or bus), and specifying post fx.
Note that I also put together a tutorial on how to sidechain compress in Ableton Live, so refer to that for information on using sidechain compression in that DAW in particular, and specifically with the kick and bass combo I’ve covered:
With the kick set as the sidechain source, the compressor’s threshold will use the level of the kick to determine when compression is applied to the bass rather than the bass’ level.
We want to set this just below the peaks of the kick when it triggers. Setting the sidechained threshold too low on a live recorded drum kit will potentially catch the snare or other elements of the kit, resulting in the bass being compressed more often than we want.
The compressor’s ratio will determine how extreme the gain reduction and ducking is on the bass. 4:1 is a nice compromise; turning it up will pull that bass down even more drastically if you’re not getting the room that you want for the kick.
I like a fast attack and short release on my sidechained compression, as well, so that it pulls the bass down fast but returns it to its uncompressed state relatively quickly once that threshold is no longer met, meaning the kick isn’t playing anymore.
We just want that quick flash of the bass being yanked down to give the kick the breathing room and dominion over the low end when it needs it. Don’t set the release SO short that it leaves an artifact and makes the bass sound unnatural – the release is an off ramp, so give it at least 20ms to come back to full effect.
Aesthetic Effects
We can apply sidechain compression to any track in our mix to be controlled by the behavior of any other track.
A popular “aesthetic” use of this effect is to chain a relatively consistent and prolonged instrument to something more staccato to give it a choppy, bouncy effect.
I like to drop a compressor at the end of my processing chain on a pad – an instrument known for playing long, drawn out notes without much or any dynamics in the performance.
I’ll then sidechain that compressor to the snare for example, something which has a lot more life to it. Set the ratio to a more extreme figure, something like 8:1 or even maxing it out. This absolutely yanks down the level of the pad for those split seconds when the snare triggers (setting the threshold to catch the peaks) to give a lot more life and bounce to what was otherwise a bland pad before.
This is just one example – the only limit with sidechaining is your imagination!
Also note that compression isn’t the only tool you can use sidechaining with. Actually, speaking of the kick and bass, I typically prefer to use sidechain EQ to pull down just the specific frequency band on my bass that the kick drum needs:
This is very easy to do using my favorite plugin in FabFilter Pro-Q 3 as I detailed in my overview of how to use dynamic EQ
As transparent as we can make sidechain compression, sidechain EQ results in an even more transparent adjustment as we’re exclusively pulling out the frequency the kick needs and leaving the rest of the bass’ frequency profile unbothered.
Again, outside of practical uses, thinking outside the box can result in some very interesting and potentially ear candy leaning effects to keep your listener’s engaged. How do you use sidechain processing in your mix?
