Eurorack Module
X
4Quadrant Multiplier

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.
» read more
One of the input, X in, is equipped with several manual control options: A switchable exponential converter for VCAlike 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.
4quadrant means: In comparison to a common VCA (2quadrant 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 (≙ 4quadrant operation). » read less
» read more
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.
4quadrant means: In comparison to a common VCA (2quadrant 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 (≙ 4quadrant operation).
» read less
Soundfiles
Ringmodulation of synthesizer and rhythm machine
X in: Korg MS20 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)
Or listen on
https://soundcloud.com/cgproducts/sets/x
Block Diagram
Examples (linear mode)
Linear mode: switch ‘lin/exp.’ in upper position
X in or Y in = 0 ⇨ W out = 0  X in polarity ≠ Y in polarity ⇨ W out = negative  

X in  0  ±  +  +  −  − 
Y in  ±  0  +  −  +  − 
W out  0  0  +  −  −  + 
X Offset  X in  Y in  W out 

0  
+2  
+4 
Examples (exponential mode)
X Level: ≈3 (≙ X in amplification ≈ 1); exponential mode: switch ‘lin/exp.’ in lower position
X Offset  X in  Y in  W out 
+3,5 
Due to the rectifying characteristic of the exponential mode, with different settings of the X input level and X offset several modulation shapes can be achieved for Y in (Y in: +10V DC voltage)
X Offset  X in Level  X in (ca. 8V pp)  W out 
+3,5  1  
+2,5  2  
0  4  
4  7 