£149.00 (£124.17 ex VAT)

Quad Voltage-Controlled Polarizer, with Cascaded Mixing

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SKU: blinds Categories: , , , ,


Mutable Instruments BLINDS is a 4-channel voltage-controlled signal polarizer. Each channel consists of a polarizer circuit, also known as a four-quadrant multiplier. This circuit acts like a VCA, except that a negative control voltage will cause the output signal to be inverted, instead of being silenced. Blinds’ outputs are daisy-chained, allowing adjacent groups of 2, 3, or all 4 channels, to be mixed together.

One can think of Blinds’ as a voltage-controlled version of Shades, the control center for all the modulation CVs used in a patch. Many other uses are possible, though. For example, each individual channel can be used to scale/offset a CV; and with audio rate modulation signals, each channel acts like a ring-modulator, with massive potential for drones and feedback patches.


  • All inputs DC-coupled.
  • All inputs handle audio-rate signals.
  • Input impedance: 100k for all inputs.
  • CV offset range: +/- 5V.
  • Gain scale: linear, a +5V CV translates to a gain of 1.
  • Gain range: +/- 2.
  • Open-source hardware.

Ring Modulation

A ring modulator is an imperfect four-quadrant multiplier realized with a diode ring circuit. Because it is based on a bipolar VCA circuit, Blinds realizes a purer sounding version of ring-modulation, but bells & Daleks are still very much achievable!

When Blinds is used as a ring modulator, with audio rate signals going in both inputs, the big knob controls a very interesting parameter: carrier rejection (how much of the unmodulated signal will “bleed” on top of the ring-modulated signal).

Width: 12hp
Depth: 25mm
Power: 70mA @ +12V / 70mA @ -12V