A two channel Low Pass Gate, providing simultaneous voltage control over amplitude and frequency content of a signal. It is in essence, a Voltage Controlled Filter Amplifier (VCFA) that has an extremely organic response to control signals. The Low Pass Gate is a classic West Coast synthesis circuit.

Revision 2 adds audio side-chain compression and expands CV generation and processing capabilities.


  • Width: 8hp
  • Max Depth: 24mm
  • Power:
    25mA@ +12V
    25mA @ -12V
  • $215
  • Where to buy
  • manual:
  • optomixrev2manual.pdf
  • optomixmanual-japanese.pdf
  • optomixrev1manual.pdf
  • features

    • Damp circuit updated to accept audio as well as CV allows for patching side-chain compression.

    • STRIKE INput allows use of Gate signal to trigger Low Pass Gate circuit, "plucking" or "striking" the vactrol

    • DAMP and STRIKE parameters combine to allow for easy programming of percussive sounds (sharp Attack w/ Voltage Controlled Decay)

    • Normalization of a positive offset to the Channel inputs allows for level-shifting of CV, Envelope Generator and even subtle non-symmetrical clipping of signals

    • Summing stage with an AUXiliary IN allows for chaining of multiple units creating larger mixes

    • Direct coupled, process audio or control signals

    • Utilizes 4 vactrols

    • Pairs well with modDemix modDemix and MATHS