FabFilter Pro-C 2 offers the possibility of feeding an external signal to its side chain, so
that you can make it trigger on a different signal than the audio it is actually processing.
Feeding a signal to a plug-in's side-chain inputs works slightly different in various hosts. This
topic describes the procedure for some of the most popular hosts around: Cubase, Logic Pro, Ableton Live and
To explain how it works, we use a scenario with two tracks. The first one contains the audio
that we want to process with Pro-C 2, which we'll call the main track from now. The
second track contains the audio that we want to route to Pro-C 2's external side-chain input and
use as trigger signal. We'll call this track the side chain track.
After setting up everything according to the instructions below for your host, you can check
whether everything is routed correctly. Play the audio and enable FabFilter Pro-C 2's Audition
button to listen to the side-chain signal. While auditioning, the real-time display and metering
show the side-chain level, so you can easily set a correct trigger threshold. Afterwards, disable
the Audition mode again. Now, you'll hear that Pro-C 2 on the main track will react to the sound
of the side-chain track. Of course, you can fine-tune the plug-ins settings to customize the
Open Cubase and create a new empty project.
Add two audio tracks that we'll use as main track and side chain track.
Add audio files on both the main track and the side chain track. You can simply drag audio
files from a Finder/Explorer window onto a track.
Open the Mixer. In the main track, click on an empty insert slot and select the VST 3
version of FabFilter Pro-C 2 in the Dynamics menu (note the VST 3 icon which looks like
In the right top corner of the plug-in interface header, in the 'Side Chain' menu, choose
the side chain track. Now, the signal from the side chain track is sent to FabFilter Pro-C 2's
external side-chain input.
Open Ableton Live and start with an empty arrangement. We'll use Track 1 as the side chain
track and Track 2 as the main track.
From the folder menu's on at the left top of Ableton Live's interface, drag different audio
clips to the first empty slots of Track 1 and Track 2.
From the VST (or Audio Units) plug-in menu, also at the left top of Ableton Live's
interface, drag FabFilter Pro-C 2 onto Track 2, the main track.
In Track 1 (the side chain track) in the 'Audio To' menu select 'Track 2' instead of the
default 'Master'. Now, an extra menu appears right below: choose 'FF Pro-C 2 3/4' instead of
the default 'Track In' to route the track's signal to FabFilter Pro-C 2's external side chain
Note: In the scenario above, you won't hear Track 1 (the side-chain
signal) anymore, since its audio is only routed to Pro-C 2's side-chain inputs. To avoid
this, use one additional track (e.g. Track 3), choose 'Track 1' from its 'Audio From' dropdown
menu, and in the 'Audio To' menu select 'Track 2' instead of the default 'Master'. Now, from
the extra menu below choose 'FF Pro-C 2 3/4'. Of course, you can now leave Track 1's 'Audio
To' setting to the original 'Master' so you will still hear the signal.
Open Pro Tools and start a new empty session.
Create two audio tracks that we'll use as main track and side chain track. Add audio files
to both track.
Open the Mix window to display the tracks with their Insert slots and Sends slots.
In the first 'Sends' slot of the side chain track, choose 'Bus 1'. The track view for Bus 1
will open: set its level slider to 0.0 dB so the bus actually produces audio!
In the first 'Inserts' slot of the main track, choose Dynamics > FabFilter Pro-C 2.
Now, in the 'Key Input' menu of the plug-in interface (just above the FabFilter logo),
choose bus > Bus 1 instead of the default 'no key input'. Now, the audio from the side chain
track is routed to Pro-C 2's external side chain input via Bus 1.