Sidechaining with ReaComp

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Side-chaining with ReaComp

What Is Side-Chaining?

In essence, a side chain is where you use the output of one track to control the output on another track. You could use Sidechaining if you want to have your background music on one track automatically lowered in volume, or ducked, when there is speech on another track. So for example your podcast intro music is ducked when you start speaking.

How To Set Up A Side-chain

In the side- chain we will be setting up in this tutorial, we will be sending the audio from our vocal track to the music track. We will still want the vocal track to go straight to the master track so we can hear it. The copy that is sent to the music track will not be heard in the master, however it will be used to compress the volume of the music, or in other words, to duck the music.

First, create two tracks. In this example, track one will be called music, and track 2 will be called voice. This article assumes that you already know how to create tracks. If not, then read this article to learn how.

Now we have a track with music, and a track with voice. The first step is to change the music track from a standard 2 channel stereo track to a 4 channel track. The first two channels are your standard left and right channels, channel 3 and 4 will be auxiliary channels, meaning that you won't hear the audio being sent to those channels. To change the track to a four channel track, press I on the music track, to open the routing dialogue. Tab until you hear, “track channels.” Arrow down to change from 2 channels to four channels. Then press escape to exit the routing dialogue.

Next, setup a send, so that the audio from the vocal track is being sent to the music track. You can press I on the vocal track to enter the routing dialogue, tab til you hear, “add send.” Arrow down to get to your music track. When you're there, wait a second for the send to add, then press escape to leave the routing dialogue. Your send has now been added.

Next, set the destination of the send from the vocal track to the third and fourth channel of the music tracks. This will send the audio from the vocal track to the auxiliary channels of your music track. This means that the audio on your vocal track is being heard through your vocal track, but is also being sent to the auxiliary channels of your music track, so that you can use it to influence the music track.

To send the vocal track to channels 3 and 4 of the music track, press I on the vocal track. Tab until you hear, “send to track one, music.”

Now, we can add a compressor to our music track. In this tutorial, we are using the included compressor, Reacomp. Press F on the Music track to open the FX dialogue. Add ReaComp.

Once added, tab through the settings of ReaComp until you get to “detector input.” Set the detector input of ReaComp to aux 3/4. This means the compressor will be influenced by the audio being sent to it on channels 3 and 4, in this case, the audio from your voice track.

Finally, we need to set up the compressor suitably to compress the music enough to hear the voice over. Set the ratio to a suitable value, perhaps 4/1 or higher. You can use the precomp and attack parameters to affect how quickly the audio is ducked and the release parameter to affect how quickly the audio returns to it’s original volume once the voice over stops. The lower you set the threshold, the quieter the music will be while it is being compressed.


We have now set up a side chain to duck our music while speaking. This may seem fairly complex at first, however understanding the concepts covered will help with lots of tasks you might want to undertake in Reaper, or any professional DAW

Audio Tutorial

In this audio tutorial, Garth Humphrey's talks you through creating a side chain in Reaper with ReaComp. Download the audio tutorial here.