Audio - The Sidechain in Reaper 3

Using the Sidechain in Reaper 3?

What is Sidechain?

This is an audio compression method (volume management).

This technique allows you, for example, to lower the music volume when talking into a microphone.
But it is mostly used today in electronic music, to gives a rhythmic background.

The sidechain ("side" meaning "next" or "parallel" and "chain" for "channels") is simply a way to route a sound discretely to modulate another channel of your music.


There are several ways to integrate the sidechain in Reaper.
Reaper allows to use the sidechain to route sound effects, using the plugin supplied with, but also via the automation on the gate ...

Normal Sidechain

  • Insert a track in Reaper. Insert Menu -> Track
  • Add a regular kick on this track. The sidechain track should contain only one kick, unless you want to make really special effects.
  • Now its time to handle the routing issue. Open the routing management tab for the side chain track sidechain by pressing the io button.
  • If you had a kick in your music (which makes 2), then uncheck the "Master / Parent Send".
  • Then click on "Add new send" and select the track you want to process.
  • Now click on the second scrolling list of Audio 1/2 -> (New Channels on Receiving track) -> 3/4.
  • Then put the MIDI None.
  • Add ReaComp VST effect at the end of the effects.
  • Turn on the Detector Input on Auxiliary Input L + R.
  • Set the ratio to 10, set Threshold to -15 dB and here you are with an overview of the sidechain.
  • You can modify the values according to your preferences.
  • You can also check the Auto make-up and Limit Output features.

Sidechain for the Gate

Here is how to use the Sidechain with the gate in Reaper. Proceed as for a normal sidechain but instead of adding the ReaComp, use the ReaGate.

Automating Sidechain

  • In this case we will use the sidechain to modulate automation.
  • You will need a track with a kick.
  • Create sidechain normally but stop just before adding the effect ReaComp.
  • Go to the track with the effect to be treated. Click on env
  • And here is all the parameters of your effect on this track.
  • Use the Cutoff effect of a synthesizer, for example.
  • Look for the parameter in the (long) list. Click on mod.
  • Check Audio control signal.
  • Put Track audio channel on 3/4.
  • And from there, you can edit values according to your preferences.

Thanks to DJ Fire-Black for this tip.

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