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Linear Bipolar VCA Unit

Also known as a ring mod.

mono version

stereo version


Overview

This unit is used to modulate the amplitude of one signal with another signal. Simply put, this unit multiplies the two signals together. This unit’s input signal is multiplied by the value of the level parameter. The stereo version of this unit adds a panning control.

tip

Multiplying two signals together is also known as ring modulation where the input signal is the carrier and the level signal is the modulator.

pitfall

Experiencing VCA bleed? Use the unipolar VCA instead. This bipolar VCA lacks the rectification on the modulation signal that is needed to completely close, especially when using (relatively noisy) externally generated signals.

Controls

level

Gain/Bias

The unit’s input is multiplied by the value of this control.

pan

Gain/Bias | stereo only

Pans the signal between the left and right channels according to the following (linear) panning law:

/er-301/pan-law.png

Some examples:

  • A value of -1 will hard pan to the left.
  • A value of +1 will hard pan to the right.
  • A value of zero will pan to the center (no attenuation for both channels).