Eurorack Module

X

4-Quadrant Multiplier

Front view

Ring or amplitude modulation
Voltage controlled amplification
Exponential conversion
Wave shaping
Dynamic expansion
One input with adjustable level and offset control
Works both with audio and CV signals
Red LED for overdrive indication
Easy to use

Width: 6 HP
Dimensions: 128,5 mm x 30,2 mm
Depth: 35mm
Supply voltage: ±12V
Current consumption: ≈25mA
Optionally with banana or 3,5mm minijack

The amplitude multiplier module X is multiplying the two applied input voltages X in and Y in. A multiplication of 2 both positive or both negative input voltages will result in a positive output voltage, while a multiplication of 1 negative and 1 positive signal input will generate a negative output signal (phase inversion). The results are ring/amplitude modulated sounds or control voltages.

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One of the input, X in, is equipped with several manual control options: A switchable exponential converter for VCA-like applications etc.; a Level knob to amplify or attenuate the input signal, an inversion switch and an adjustable Offset voltage, which can be added to this input. The offset knob is also allowing a ‚dry/wet‘ style control over the Y input and the modulated signal, or may be used to shift the multiplier’s working point. In addition, there is a little red LED indicating when this input is becoming overdriven.
In comparison with the 1st input X in, the 2nd input Y in has no extra features or controllers – to reduce the complexity and keep the handling more simple.
The output (W out) is internally attenuated to ensure that the product voltage of X×Y is almost in the range between the ±12V voltage supply.
4-quadrant means: In comparison to a common VCA (2-quadrant operation), a multiplier is processing both positive and negative (control) voltages, causing a ± polarity inversion of the modulated signal for input voltages with unequal polarities (≙ 4-quadrant operation).
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Drawing
right side
left side
Banana version
Banana version left

Soundfiles

Ringmodulation of synthesizer and rhythm machine
X in: Korg MS-20 filtered VCO and noise with different filter settings;Y in: Rhythm machine

Ringmodulation of rhythm machine and trumpet
X in: Rhythm machine; Y in: Preamplified trumpet; different X Offset settings

Ringmodulation of rhythm machine and cymbals
X in: Rhythm machine; Y in: Preamplified cymbals; different X Offset settings

Stereo panorama control with 2 X modules X in 1: triangle/squarewave, X in 2: triangle/squarewave inverted;
Y in 1+2: Rhythm machine / VCO

Envelope shaping with 2 X modules X in1+X in2: trianglewave; Y in 1: VCO; Y in 2: Noise
In exponential mode, depending on X Offset and X Level settings, different modulation waveforms can be achieved.

Noise modulation with 2 X modules and Delay1022 Xin1+Xin2 (exponential mode): pink noise, Yin1: white noise; W out1: Delay In
Y in2: +10V DC voltage W out2: Delay time CV input
Multiplier 1 (modulating white noise) is followed by the delay (delay time modulated by multiplier 2)