How to make a sidechain compression

[wibem]

I'm struggling with the sidechain compression in Mulab. To do this I have found the level compressor, which I put behind a synth in a rack. Then I send the audio from a drum rack to the synth rack (with the level compressor module in it) and get a sidechain compression, albeit I really don't understand how that works. But when I put the level compressor module inside a Mux, connect it with audio in and audio out, and put this after the synth, it doesn't work anymore. Why? Sorry, if that's a stupid question. I just don't understand, how it all works.

[MuTools]

As the word "side-chain" says it uses a second audio input to control ("compress") the volume of the main audio input.
So goal is to route the control audio signal (eg a kick drum) to the 2nd input of the side-chain compressor.
When using racks this is done by setting up Auxiliar inputs/outputs, see https://www.mutools.com/info/M8/docs/mux/rack.html
Attached an example project.

[wibem1]

I can't open the project, because it was made with a newer version of Mulab. My version is 8.7.6.

[wibem]

As the word "side-chain" says it uses a second audio input to control ("compress") the volume of the main audio input.
So goal is to route the control audio signal (eg a kick drum) to the 2nd input of the side-chain compressor.
When using racks this is done by setting up Auxiliar inputs/outputs, see https://www.mutools.com/info/M8/docs/mux/rack.html
Attached an example project.

Why does it work without a second audio input, when you send the audio signal of the drums to the synth rack and put a level compressor after the synth?

[MuTools]

I can't open the project, because it was made with a newer version of Mulab. My version is 8.7.6.

You can download M8.8.3 here: https://www.mutools.com/mulab/app-patch/

[MuTools]

Why does it work without a second audio input, when you send the audio signal of the drums to the synth rack and put a level compressor after the synth?

See the info on "Level Compressor" on https://www.mutools.com/info/M8/docs/mu ... dules.html

[wibem]

I still don't understand completely. The level compressor has two audio inputs. But how does it work, if there is no first and second signal like it is in the project, which you sent to me? This modul is in a rack behind the synth, which should be compressed. How does it get the first and the second signal? Is there a kind of separation inside the rack, which signal is the first and which is the second?

[MuTools]

Did you read that doc page? See https://www.mutools.com/info/M8/docs/mux/rack.html

"If a certain rack slot plugin uses more than one input/output, you can export these auxiliary inputs/outputs as rack inputs/outputs via that slot plugin's context function "Setup Aux Ins/Outs". If you do so then the aux inputs/outputs will appear as extra rack inputs/outputs in the modular area. This is especially useful for multi-out plugins (eg. drum machines) and for setting up side-chaining."

That example project i sent earlier indeed uses this option for auxiliary rack inputs/outputs so that the kick can be routed to the 2nd input of the compressor.

[humanboeing]

If you use the level compressor module in a rack then the signal is automatically routed to the first audio input and the second audio input is untouched. By default the compressor doesn't need a trigger, because what triggers the compressor is the threshold level (compression will happen when the signal goes above the treshold). However there is a function to trigger the compressor with another signal and for that is the second audio input. You can route another signal to this audio input and it will act as a trigger. It can all be set up without going into the modular area.

So the 1st signal is automatically routed in a rack.
For the 2nd (sidechain) signal you can do it like that:
1. Right click on the compressor which is inserted into a rack
2. Set up auxiliary ins/outs and change the value to 1
3. Insert a send on the track which you want to act as a trigger and make sure the send targets the rack which you want to compress

[humanboeing]

Also if you set the auxiliary inputs for a rack and then you hover over at that new audio input pin in modular area it will display its name : Level compressor Audio input 2

It may be a bit misleading because when you look at the rack in modular area it looks as if there is some audio going before a synth patch, but that audio signal goes directly to the compressor and skips all modules on the way.

[wibem]

Ah, thanks, that helps a lot to understand the function of the sidechain compression. But how does it work, if you put the level compressor inside of a Mux?

[MuTools]

You can add an extra audio input in that MUX and route that to the 2nd audio input of the LC.
Then you can route the source control audio signal to that extra audio in of the MUX.
Almost just like in real life when using cables.

[wibem]

Thanks