Duck with a Sidechain

A compressor with a sidechain input listens to one signal and turns down another. Put the compressor on the track that should duck, and feed the track it should duck under into its sidechain port with connect_input.

Connect the sidechain

Place the compressor first — the port belongs to the effect on the track — then connect the source to its port:

use "std/instruments" { Sampler, Kit };

let kick = AudioTrack("kick");
kick.set_instrument(Sampler(Kit("CR-78")));
kick << [bd*4];

let bass = AudioTrack("bass");
bass.set_instrument(Instrument("Surge XT"));
bass << [C2 _ C2 G1];

let comp = Effect("comp", "TDR Molot GE");
bass.set_effects(#[comp]);
comp.connect_input("Sidechain", kick);

PLAY;

Then turn on the compressor’s own sidechain or external-key switch, and set its threshold, ratio and release by ear. The kick reaches the port only; it is not mixed into the bass.

Find the port name

The port name is the plugin’s own, matched exactly: MCompressor and TDR Molot GE say "Sidechain", Shadow Hills "Stereo Aux In", FETish "Aux". A name the plugin doesn’t have is an error that ends with the ones it does — Available ports: … — so connecting with a guess shows you the list.

If the plugin reloads

A connection to a port that disappears — the plugin reloaded, or changed its buses — comes back when the plugin offers the port again. You don’t connect it again.

Related

• Use a Plugin — load and set up the compressor
• Sidechain a Custom Effect — a dsp effect with a sidechain input of its own
• Audio: Plugins — connect_input