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Four-Channel Voltage Controlled Mixer, Quad VCA.

Our four channel voltage-controlled mixer (and quad VCA) comes in two versions.
The linear version — blue sum level knob — is ideally suited for cv mixing duties, whilst the exponential version — red knob — performs best with audio applications.

Two channels have unipolar attenuators for both signal and cv inputs, with the remaining two other channels having bipolar controls (aka "attenuverters") for signal and cv. Use the former channels when you absolutely need precise control over signals, and use the latter when inversions and shifting and mangling is what you seek.

At the 3'o'clock position the sum level control knob is at unity gain; beyond that it goes into overdrive mode, adding 3dB of gain, with a smooth soft-clipping limiter behind it to keep your signals in check.

In case you need more than four channels, simply plug in another Quadsum to the auxiliary input.

An optional QS+ expander module transforms the Quadsum into a full-blown quad VCA, by making the individual outputs of each channel available.
The sum level gains (no pun) a control input too, enabling amplitude control over all four channels simultaneously.

Additionally, one can create a four-channel post-fader submix of the Quadsum outputs. This comes in handy when you'd like to have two differently balanced versions of the same mix and send them off to separate signal flows. Or simply send the submix output back to the auxiliary input of Quadsum for some good old feedback fun.

Quadsum is an excellent companion to our Variphase and VCO II oscillators, but of course it can be deployed to good use anywhere in a modular system as well.

Specifications Quadsum

    Available in Exponential (audio) and Linear (cv) versions.
    Per channel :
  • Signal input with attenuator; bipolar on channels 3 and 4.
  • Voltage control input with attenuator; bipolar on channels 3 and 4.
  • Initial level control.
  • Gain response is 10dB/V (starting at -100dB @ 0V).
  • Channel is off @ 0V control voltage, unity gain @ 10V control voltage.
  • Frequency response : DC to 20kHz for both signal and modulation.
  • Bicolor signal indication LED.

  • Auxiliary input for cascading Quadsums.
  • Sum level control with 3dB overdrive and soft-clipping limiter.
  • Dual Sum outputs with overload LEDs.

  • Fully analog signal & cv paths.
  • Skiff friendly : 41mm deep behind front panel, including power header.
  • Shrouded header on the power supply connector, no risk for reverse polarity.
  • Includes printed manual and power cable.

  • 16hp
  • tba +12V, tba -12V, 0mA 5V

Specifications QS+

    Optional. Works for both audio & linear versions of Quadsum.
  • Individual channel outputs(turns Quadsum into a fullblown quad VCA).
  • Sum Level control input with attenuator.
  • Postfade 4-ch submix of Quadsum outputs.
  • Submix output.

  • Skiff friendly : 21mm deep behind front panel.
  • Includes printed manual and power cable.

  • 8hp
  • Powered by a Quadsum.