Sidechains? Huh?

Can someone explain side chains and the best approach to using them. I’m fairly versed in Ardour, but am guilty of not using side chains mostly because I’m not sure how to use them and/or for what?

If I want a specific plugin to interact with more than one region/track, I typically add a BUS and route all inputs to the MASTER output. But, I’m limited as to what plugins I can use. For example, I typically use the SC4-Mono plugin for compression cause the SC3 plugin complains about my setup. The SC3 has “sidechaining,” but I’m at a loss on how to actually use it.

If someone has a link or an explanation, I’d greatly appreciate any kind of quick tutorial. Thanks!!

Sidechains are used to trigger the compressor (or gate) by a different or modified signal than the one to be processed. Examples are ducking and de-essing.

Maybe there are better descriptions on specialized sites, but I think the articles on Wikipedia are a good starting point:

You should probably also be aware that (to my knowledge) there is currently no means by which to use a sidechain within Ardour. There is just no way to route audio into the sidechain input with Ardour’s model of using a linear stack for plugins. Until there is a node based plugin model implemented, there really won’t be any way to get around this.

You can use them if you route the audio to an external app that uses nodes such as Om or Ingen.

SidechainComp in Ardour …

So in the case of ducking, how would I create a side-chain in Ardour so that the bass “ducks” when the kick meets a certain db level? How would I create a side chain?

Assuming you already have 2 tracks for kick and bass, you need to create a bus with 2 inputs. This bus gets the SC2 plugged in. That’s the mono-sidechain comp by Steve Harris.
Now, all you need to do is, feed the bus input 1 with kick and bus input 2 with the bass (you do it by sends or trackoutputs - your choice).

also read here


Awesome… took me awhile to figure out the “sends” as I haven’t worked with those at all. Once I got rolling though, seems to make better sense. Thanks.