Propellerhead Reason 4: Set up sidechaining with Reason's MClass comompressor
1. From the Create menu, add an MClass Compressor, Spider Audio Merger & Splitter, and the instrument you want to process (for example, ReDrum).
2. Hit the Tab key to flip the rack around, and start patching. Connect the ReDrum Stereo Outs to a pair of Spider Audio Merger inputs, and the Merger output to the MClass compressor input.
3. Patch the Snare drum output (e.g., ReDrum output 2) to the Spider Audio Splitter input (previous connections not shown for clarity). Patch one set of Splitter outs to a pair of Spider Audio Merger inputs, and another set to the MClass compressor Sidechain In.
4. Patch the MClass Compressor output to a mixer (e.g., Line Mixer 6:2) or the hardware interface; if using a mixer, patch it to the hardware interface as shown (again, previous connections are not shown for clarity).
5. Hit Tab to turn the rack around again. Adjust the compressor controls (Threshold, Ratio, etc.) for the desired effect. To monitor the signal coming in to the sidechain input, click on the Sidechain Solo button.
-In Step 3, taking an individual ReDrum out removes it from the main stereo mix. Splitting the snare drum output and sending it to the Spider Merger mixes it back into the main mix, but you could also send the split snare output to a mixer channel. This would allow independent control over the snare drum and overall mix.
-The sidechain input can come from anywhere—not just the instrument being compressed.
-For frequency-dependent sidechain compression, insert the MClass Equalizer between the sidechain signal and the MClass Compressor sidechain input. Use the Sidechain Solo button to monitor the sidechain signal, and adjust the MClass Equalizer to boost or cut the desired frequencies.