This module is a combination of four simple VCA circuits run into a summing mixer. It was designed primarily to work with audio signals, being the final module in a system before going to an amplifier or recording interface. It was designed to be built by beginners, be as simple to use as possible and to use inexpensive parts. Each VCA his it's own individual output which is wired to be taken out of the mix when used.

For complete descriptions of the way the module is used, download this PDF file.  

Rev 3.1 Boards are in stock and cost $8 each.
I have unfinished eurorack panels for this project. They are 12HP, and cost $7.5 each. Check out the panels page for availability. If you'd like to make your own panel, feel free to use my drill pattern for 12HP. That image is at 300dpi.
Grayscale has some nice looking finished aluminum panels for this project.
And if you use the Muff Wiggler forum, a user with screename "Barcode" has a finished acrylic panel design. He can be e-mailed at