Mixer II


Ultra simple two-channel mixer in 2hp. You can mix audio signals, such as control voltage, like envelopes. There are attenuators and mute switches per channel.

I built the first iteration of this module for my techno rack. I needed a slim mixer to sum the two channels of my hihats module because I didn’t have more channels left on my main mixer 💡

In the second run (revision 2), I then needed the requirement to be able to sum control voltage as well. I wanted a way to mix envelopes for side chaining and have them non-inverted.

At some point it bothered me more and more that it clicked so much in the sound when muting with the switches. That’s why I removed them completely with revision 3. Mute is still possible with the volume pots. I also missed the variable master gain, with which I could still adjust the output, especially when mixing envelopes from other modules. That’s why I added it as a trimpot to be more flexible.


  • ✅ 2 channels
  • ✅ Attenuation per channel
  • ✅ Mixes audio signals and control voltage
  • ✅ Variable master gain
  • ✅ Buffered inputs


Right and left view on the module:


Control board (bottom):


Main board (top and bottom):



Revision 1 (stripboard prototype)

Revision 2 (breadboard prototype)

What’s new? Implemented a non-inverted output.

Revision 3 (breadboard prototype)

What’s new? Removed switches (and thereby their clicking) and added variable master gain.

Revision 4 (PCB prototype)

What’s new? Brought it on PCB level.

Wait, there's more?

See all modules