Mixing : Plug-In and Hardware Inserts : Side-Chain Input : Using a Key Input for External Side-Chain Processing

Using a Key Input for External Side-Chain Processing
To use a key input for external side-chain processing:
1 Click the plug-in’s Key Input selector and select the input or bus carrying the audio you want to use to trigger the plug-in.
 
2 Click the External Key to activate external side-chain processing.
3 Press the Spacebar to begin playback. The plug-in uses the input or bus that you chose as a key input to trigger its effect.
4 During playback, do any of the following to fine-tune key input triggering:
*   
To hear the audio source you have selected to control the key input, enable Side-Chain Listen or Key Listen (depending on the plug-in). When finished, disable Side-Chain Listen/Key Listen to resume normal plug-in monitoring.
*   
To filter the key input so that only specific frequencies trigger the plug-in, use the filtering controls (if available) to select the frequency range.
5 Adjust the plug-in’s Threshold control (if available) and other controls as needed.