Modular-Synth-Inspired daughterboards


Well-known member
I think it'd be cool to have little daughterboards for pedal modding. For example replacing a simple tone stack with a diode ladder filter would radically change the sound of a pedal. Or you could use an ADSR circuit to change your guitar's attack. Or you could use a simple LFO to automate pedal parameters. Or you could use Pulse Width Modulation to change the instrument's timbre. Etc etc etc...

Edit: @bowanderror adds --------

I've gone somewhat down that route and wanted to add a few things for you to check out (if you're interested). Most modular & synth circuits are either +-12V or +-15V, but there are a few somewhat pedal-friendly filter schematics out there:

Steiner-Parker VCF (Electronic Audio Experiments) - 9V supply to +-9V with charge pump - "This filter is best known these days as the multimode filter in the Arturia Microbrute. Has a very aggressive drive sound when the resonance is cranked up. This implementation is pretty close to the one drawn up by Yves Usson here. Changes include a redesigned power supply, input buffer, active pregain control, active volume control, some extra low pass filtering to tame parasitic oscillation, and limiting resistors on the sweep control to keep it in the guitar range. A meter is recommended for calibration."

Japanese Diode Ladder Filter Autowah - Can't find a ton on this, but supposedly it's from some old DIY book. It's +-9V, but could use the same charge pump as above.

EFM VCF6c +9V Diode Ladder Filter Schematic (Electronics for Music) - I haven't personally tried this one, so I'm not sure of the quality, but EFM is usually reliable.

Korg MS-20 Filter - Classic gritty OTA filter. I think this 9V version goes all the way back to Tim Escobedo

MoogerFooger MF-101 Transistor Ladder Filter (User Manual) - I only recently found this, and it's a bit of a holy grail. Definitely more difficult than the others, but Moog Transistor Ladder Filters sound AMAZING! I recently posted about my own experiments here (not 9V friendly).
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