ADDAC604 Dual Filter

While developing our ADDAC105 4 Voice Cluster module we made a new multimode filter to place after the summing mix stage. We were so pleased with its sound that decided to release it as a dedicated filter.
To make it more interesting we duplicated its circuitry to be able to use it in a stereo signal path.
To make it more versatile we added a switch to set the working mode from Stereo to Dual Mono where both filters can be used independently.

In Stereo Mode the Left Cutoff is used to control the Right Cutoff.
In this case the Right Cutoff Knob and CV Input are simply bypassed and will have no impact on the Right Channel operation.
This allows immediate sync of both filter frequencies when the Stereo position is engaged.
Optionally there’s a jumper in it’s back that, when placed, connects the Right Controls back to the Right CV control allowing the possibility to control the offset of the Right Channel Cutoff.

Resonance is independent on both Modes and still has to be set manually to match both channels.

Both the Audio and CV inputs are normalled from the Left into the Right channels.
As standard plugging any input to the Right channels removes this connection.