Serial - parallel filters

Hi! I know that some of you are trying to make experiments with two filter boards at the same time and all that stuff. How’s that going?

Some friends of mine have asked me if it could be possible to use two filter boards, in a serial or parallel configuration. I know that is very difficult to achieve and that this is a feature that maybe not everyone is waiting for. But anyway, I’m just curious about it

Thinking about it, by now I imagine that the problems or things to think about could be:

  • Providing power supply for the 2nd filter board
  • How to send filter values to the 2nd filter board
  • There’s no pages for adjusting the values of the 2nd filter board (an additional menu would be required)
  • How to mix both sound sources from the two filter boards
  • No existing cases have room for 2 filter boards

That, or simply making a new filter board that combines two on the same PCB (if that’s possible, I don’t know), making menus for controlling it and find a way to mix the sound from the two filters (in case that isn’t mixed internally in the board).

Anyway, I’m really happy with the Shruthi1 as it is! Just trying to reply my friends questions, but as I’m not an expert in electronics and programming just wanted to ask you about it.

The next firmware update comes with some basic support for filter boards that contain 2 VCF. There’s a second menu page for the second VCF with its cutoff/resonance settings, and a menu for selecting topology/filter type.

Cutoff2/Resonance2 are sent to CV1/CV2, filter configuration is output as a 8 bits value on the digital expansion port. This is in preparation for 2 SVF filter board I really want to do.