Perk is a percussion aid. My solution for drums is to take any input waveform, apply a filter and an envelope, then a VCA to complete the voice.
The envelope goes to the filter by way of an attenuating knob, for varied tonal depth. CV over envelope length and filter; a BYO envelope jack (labeled level) can be held open to function as a direct filter and overdrive.
Join with XORBell for a funky drum voice, or the uVCO for tonal kicks!
V1 is in working order in time for Knobcon 2024 – September 6th is our debut!
| Item | Price | Note | |
| PCB/Panel | $40 | ready to go | |
| Full Kit | $100 | none avail | |
| Assembled | $150 | few available |
Assembly BOM shows this unit relies on the SSI2164, a magical chip that puts four VCAs into a soic-16 package. Three of them serve as the resonant filter, and the fourth a final stage of volume control.
Power draw measures 40mA on +12 and -12V, for a bunch of opamps and the VCA chip.
Internal noise source via the floating NPN transistor trick. This can be adjusted in amplitude to suit your transistor choice at R14.
Envelope with CV over decay uses just two parts of a TL074 and a capacitor to hold charge. I got help on that circuit from Synthfox . The big cap on top is specified as 1uF but you can put anything you like there and get different shapes and sizes out of the performance. Might be a good place to hack.
Parts are 0805 size, which are considered human solderable with a tweezers and a clear workbench. Have fine solder and be careful not to lose any little parts. Reach out with any questions, but I aim for this to be a straightforward assembly.
