ChartreArts Psilocybe Optocoupler Filter

"Spectral Mixing" filter with LP/BP/HP inputs, two outputs, and vc slope

Note: The panel shown in photos is a prototype and a little less colourful and bold than the final panels. See the last photo on the etsy listing for final panel design.

Mushrooms of the genus Psilocybe are best known for their potent psychedelic effects; which are certainly comparable to the effect of this optically-controlled filter on audio when used with the right expertise :3 Unlike most multimode filters, it has lowpass, highpass and bandpass inputs rather than outputs. This allows for interesting crossfades based on the spectra of the inputs. The filter’s utility is further extended by the bandwidth control, which allows more or less gradual crossfading/filtering. For these reasons I like to call it a “spectral mixing” filter.

Also unlike most filters is the incredibly clean and non-toxic signal path. The filter uses optocouplers for low distortion with minimal CV bleedthrough, and just two ICs are used which are both “audio-grade”. The optocouplers give a smoothly slewed CV response, and it can easily emulate buchla-style LPG plucks in lowpass mode with a short envelope and bandwidth control at max (6db).

Unlike the mushroom, this module will never induce vomiting ;)

Etsy: https://www.etsy.com/listing/453749594/psilocybe-optocoupler-filter-for-modular
Open source stuff: https://github.com/reidevries/optofilter
VIDEO DEMO:

Features:
-Simultaneous lowpass, bandpass and highpass inputs; combine them for interesting filter types, use different signals for spectral mixing.
-Variable bandwidth control that interacts in interesting ways with the resonance and mixing.
-Voltage control over frequency and slope with attenuators.
-A subtracted mix output is available, which subtracts the original signals from the filter output to "reverse" the poles (highpass takes on a lowpass character and vice versa) and allow for phasing effects.
-Very clean with low distortion and minimal CV bleedthrough, using only a few high quality operational amplifier ICs over the whole design.
-Maximum 12db slopes in LP/HP modes, 6db slopes on either side with variable bandwidth in BP mode.
-Trimmer potentiometer to adjust resonance response. Default is quite tame, but can be adjusted to be very wild.
-Hand-painted graphics on a beautiful Tasmanian Oak panel.
-10hp Eurorack module with 3cm depth, should be "skiff friendly" for some skiffs.