VC F3DB stands for Voltage Controlled Fixed Filter Feedback Distortion Bank. The simplest description is it’s an analog 16hp six band voltage controlled fixed filter bank. But with the additions of so much gain, clipping, feedback, and self-oscillation it becomes a very flexible and unique gestural sound sculpting tool capable of; graphic equalization over 6 octaves, multi-band distortion, spectral processing, crude vocoding, multi-frequency envelope following, self-modulation, and even as an instrument on its own. With no input it can be used as a pseudo chaotic “harmonic” feedback oscillator.
The filter frequencies were specifically chosen to emphasize more ambiguous and dissonant intervals. Although the frequency bands are spread out over many octaves I purposely tried to leave out “3rds” besides a major 10th at the top frequencies to even out all the dissonance below. But the frequencies aren’t exactly equal tempered, so it’s relative. The bands roughly equate to F2, B3, F#5, C6, F7, A8.
The design is based on the Moog 914 filterbank, which it borrows the frequency bands from. But this circuit uses active filters with opamps inspired by YU Synth opposed to passive cells using inductors on the original. The 88hz is a low pass -24db/oct and 7k is a high pass -24db/oct, the rest are -12db/oct band pass filters all with a Q around 4.
The hard and soft clipping circuit on the input is fairly standard which appears in many different iterations of classic guitar pedals. But it has a lot of gain and can even boost line level signals. What makes it a bit unique is the feedback on the clipping circuit which needs to be turned on by the GFB(gain feedback) switch and the amount can be controlled by the Gain FB pot which can add some fuzz/bite to the signal depending on which clipping switch is engaged or at the extremes it will self oscillate from audio rate to LFO sort of clicking range. All the clipping stages in the module are using silicon diodes.
Build: USD $400.00
More info here: Złob Modular | VC F3DB