You can do this using an Audio Effect Rack in parallel, creating your reverb chain, and follow the reverb chain with the AU/VST you want to key with a pre-fx signal form a “tapped” audio track.
(A track that uses the side chain source as the input, with the input set to “in”.)
So what you do is create an audio track, and set its input as the track you want to use as the trigger, select ‘pre-fx’ underneath the input, and set monitor to in… You then route the output of that same track back to the source track and select the AU/VST sidechain as the destination.
It’s kind of hard to explain so I uploaded some screenshots.
The thing that’s awesome about this is that you can save the rack as a preset… And since you can use reverbs in parallel in the rack this eliminates the need for a return, and allows you to compress, saturate or limit the processed signal at the end of the chain to glue it all together…
The Audio Effect Rack is the Isht!!!
Using a group as an example:
I’ve grouped a couple of drum loops together and added some processing to the group channel, before the audio effect rack.
I’ve named the group “Using a group” so it’s easy to understand…
I’ve then created an audio track and selected “Using a group” as the input source in the image below.
You’ll see I’ve also selected “Pre-FX”…
Pre-fader FX Chain:
The rack on the left has my pre-fader FX chain… Some Hornet VU for gain staging, some parallel compression and a modeled Summing Amp. (You can see the rack after it’s called “Parallel reverb rack with Loopback”. That’s the rack that will be keyed…)
The “Prarallel Reverb Rack with Loopback”:
Here’s the rack that’s let’s it all happen…
The chain on top is called Pass Through. Audio just passes through that chain untouched…
The chain on the bottom is called PreFX Reverb. This is a parallel chain.
The processed signal passes in to the reverb with channel strip processing in the previous image applied.
You can see Pro-MB at the end of the chain, which has its the sidechain set to ‘ext’.
(The speaker icon on the parallel chain should be on FYI… I captured video hoping I could upload video here but no dice… The frame of the video I selected is me toggling the chain’s audio on/off… )
Sidechain Destination Routing:
You can see that the audio is being routed back into the parallel reverb chain, with Pro-MB set as the destination in the pulldown underneath the channel called Using a group.
And since the audio is being routed to the rack it automatically silences any audio that would normally play through the channel… Now just save the rack and use it anytime