Sidechain Reverb

Sidechain compression is not the only effect you can create in Reason using the MClass compressor. Those smart people at propellerheads were insigtful enough to give the MClass compressor a Gain Reduction CV out. Which you can use to control any parameter you like.


Here I am using the compressor to pump an RV7000 Reverb Start by creating a Combinator to host the RV7000 this allows you control parameters that would not otherwise be controllable using CV’s. I’ve put the compressor in the combinator too just to keep things tidy. The Gain Reduction CV output is connected to the Rotarty 1 input on the Combinator. This allows Rotary 1 to be routed to the Dry/Wet parameter of the RV7000.

The overall effect of this setup isn’t that great, but the point is that you can use sidechaining to control any parameter in Reason.

Sidechaining in Reason

Here is how I do sidechain compression in Reason. In this example I am going to use a kick for the sidechain source, which can give the output of the compressor a bouncy catchy effect.

First of all you want to setup a default rack with a 14:1 Mixer, an MClass Compressor and a Redrum, make sure when you add the compressor its auto routed as an effect send to the mixer.

Now flip the rack and connect the Redrum’s Send 1 to the Left(mono) channel of the sidechain input on the compressor. Note that the sends from Redrum are mono outputs.

Program a basic 4/4 kick drum pattern into the Redrum device. You can add claps snares or anything else you like they will not be being sent to the compressor at this time until you turn the send knob for a particular Redrum channel.

Once the Redrum is setup how you like you can now send the kick drum to the sidechain by turning the send knob for the kick channel all the way to the right. Note that this doesn’t stop the kick from being sent to the mixer.

You can lower the compressors Threshold and raise its Ratio until you see the kick drum really pump the VU meter. Now that the compressor is pumping we need to give it something to compress. Add a synth to the rack and make sure its auto routed to the mixer. Turn up the aux send of the channel to which the synth was added.

When you play notes on the synth you will hear it go quieter when the kick drum is playing. This can be a useful way to make synth baselines fit better in the mix.

The advantage of using sends rather than using the single channel output of the Redrum are two fold. Firstly the kick drum is not muted and does not need further splitting using a Spider Audio Merger & Splitter. Secondly other elements of the beat can be sent to the sidechain in varying amounts. The advantage of using the compressor as a effect send is that many instruments can have the same compression added to them by altering the aux send of each channel.