Ray vs. Side-chaining
Hey, it's Ray.
Recently, I've been messing around with side-chaining. I'm still figuring it out, but it seems to be a gain modulator.
Gain Modulator
It's like taking an LFO and rolling it's rate to 0, while its depth is modulated by Sound 1's gain. Assume the shape is a constant static wave, or more realistically, some dynamic wave like a square (we'll get to that later). This effectively creates a constant static wave that's smoothly gated by Sound 1. Perfect for turning another sound (Sound 2) into a reactive pulse.
I did a diagram below to help show the LFO-style gain modulator:
From there, you basically have a gain FM synth with the LFO as a gain modulator, and Sound 2's gain as the carrier.
This analogy might seem unintuitive at first since in reality, LFOs don't have a constant wave. However, you can simulate this with a square wave (like we mentioned before) as half its cycle is constant. However, using a dynamic wave like a square means some parts of the sound will be unstable, which isn't great for pulsing sounds but with understanding it. Of course, we could swap the LFO for an ENV or GATE for similar or variations of the effect (and probably a smoother sound).
Pulser Side-chain
Back to side-chaining. From what I've seen, the most common gain modulator is the pulser. This has the kick (modulator) modulating the bass (carrier). This creates space (and probably vice versa for rhythm), such as the iconic pulsing sound heard in techno like in this The Bells by Jeff Mills, or this track I did called Yes to Techno:
Livecoding Demo
Focusing on the pulser (kick-bass) side-chain, here's an example of it in action with strudel:
$: stack(
s("bd:1").struct("<x!4>*4").room(.4).duck(2).duckatt(.3),
note("<<c1!4 [c2 c3]!2>>*2").s("supersaw!3 square")
.lp(2000).sus(1).detune(.3).gain("1!3 1.2").room(2).o(2)
)
You can see this demo livecoded in the video below:
Video TBD.
Many Possibilities
I'm probably only scratching the surface of this technique, and there are other more interesting ways to use it.
For example, we could use an ENV with the side-chain (like in the above strudel example), but it could go further by sustaining the effect. Or multiple sounds could be side-chained simultaneously. Or maybe harmonies could be side-chained with melodies (like radio, which is probably how side-chains were first originally used).
There's a lot of possibilities.
I might revisit this topic in the future when I have more time, but for now it's been fun.