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Triple Bipolar VCA

WMD Triple Bipolar VCA


A bipolar VCA is like a normal VCA when operated with positive control voltage. But when using a negative control voltage, the output will swing back through zero amplitude and the output will be inverted. This produces deeper modulation than a normal VCA.

Controls and I/O

  • + In – This is the normal input for each VCA channel. It drives the inverting side of the Bipolar VCA.
  • – In – This is the second input for the VCA channel. Normaled through this jack is the inverted signal from the + Input. Plugging in here converts the channel from a Bipolar VCA to a dual VCA. Negative control voltages will open the – side, and positive control voltages will open the + side. This allows you to use two modulation sources and alternate between them, while still retaining control over amplitude.
  • CV – This input jack drives the CV knob. It can handle unipolar or bipolar signals.
  • Out – This is the output of each VCA channel.
  • Bias Knob – Sets the manual gain for the VCA. Centered will have a zero output (with 0V control voltage).
  • CV Knob – This knob is a bipolar attenuator for the signal applied to the CV jack. Spin clockwise from center for positive CV interactions, counterclockwise to invert the CV.
  • Mix Out – This output jack mixes the signals from each VCA.


    Three Bipolar VCAs
    Linear Response
    Bipolar Attenuator for CV
    Mix Output Sums All Three VCAs
    Bi-color Signal LEDs
    “-” Input for Mix Through Zero
    Module depth: 25mm (Skiffable PCB Design)
    Current Consumption:+80mA/-75mA
    Panel size: 8 HP