How To Manually Draw Sidechaining Curves In Logic Pro
Suppose you are compressing a 2 bar Roland 303 bassline sample with a 4 to the floor bassdrum as a sidechaining source. The resulting volume effect will depend on the length of that bassdrum, the settings of the compressor (such as attack, release, ratio, knee), and in some cases the frequency area of the bassdrum that your compressor is responding to. That’s a lot of parameters to juggle. In the end though, all you are really doing is this: you’re changing the volume envelope shape of the 303 bassline sample.
So why not just draw the volume envelope by hand, with volume automation?
Making Sidechaining Curves: The Wrong Way
First, let me show you how not to do it:
While Track Automation is active (press A), I’ve drawn some volume automation that spans one beat(the 303 sample is 2 bars long in this example):
In the next picture, I’ve copied that curve a couple of times. I used the Automation Select tool (press Esc+Q) to select the one-beat curve, then used the pointer tool to drag (press Esc+1) while holding down ⌥ to copy it:
Looks good, right? But what if you wanted to change a linear move up in volume into a Bezier curve, using the Automation Curve Tool (Esc+Q), like so?
If you want the curve to be the same on every beat, you’ll have to start over. Bad workflow alert.
Making Sidechaining Curves – The Right Way
Instead, you’ll want to do this:
While the track you want to automate is selected, in the Arrange Window, choose Track -> New with Same Channel Strip/Instrument, or press ⌥+⌘+Enter. Put an empty region on the new track with the pencil tool. This will create a MIDI region sitting right on top of the newly created audio track. That’s a strange concept, yes, but entirely possible in Logic Pro, and without this weird possibility this article wouldn’t exist.
Now draw your one-beat sidechain curve on that MIDI region, which may look something like this:
Notice how the first track displays the volume automation too. That’s because the two tracks are the same object.
Now loop that MIDI region (press L). Result:
Note that even though the region is being looped, the automation isn’t. That’s because the automation data is like a separate layer sitting right on top of the region. These are two separate things. That top layer containing the automation can be moved into the region though. To do this, choose Track -> Track Automation -> Move Visible Track Automation to Region, or press ctrl+⌘+↓:
Fun fact: since the automation data has been burned straight into the region, you’ll still be able to edit the one-beat volume curve while Track Automation is turned off! All edits will be represented in the loops. Final thought: try other automation parameters besides volume!
That’s it for now. Have fun…