WIP: BWEEOO Eurorack filter
Under my fiancee’s and my brand RE:Flex Sound, I’m working on a versatile Eurorack format filter, with intent to bring it to market.
- Voltage controlled resonance
- Drive (pre-amplification), also voltage controlled
- “Attenuverters” instead of attenuators for modulation sources, allowing to invert modulation within the same knob rotation
- “Notch” (band reject) output
This will be my first module I intend to bring to market. Since it’s not made to work only in my setup, I’m developing it to a much higher standard than my older ones.
The module has a defacto standard 10-pin power connector, and comes with reverse polarity protection. Calibration for the 1V/Octave response is available with a trimpot. There is space on the board to install a multi-turn trimpot for those who desire even more precision.
- Circuit design for all the additions, including simulations (LTSpice)
- Schematic capture (KiCad)
- Circuit board design (KiCadD, 4-layer design)
- Front panel design (Inkscape, KiCad)
- Branding/logo design (Inkscape)
- Some assembly for through-hole parts and a few SMD parts
- Extensive testing with function generator, oscilloscope, and in context of actual modular synthesiser
Work left to be done for a new revision:
- Fix some pinout errors on the PCB
- Circuit revision for “drive” control (ranging, compensation at output)
Here’s a look at the back of the module, showing the component side of the board, including some bodges to address issues found.
The top level schematic: