Quadrature Modulator, analog synthesizer module 3rdWorldRack

Published on Jul 7, 2019 Sbranvlztronics

"The Quadrature Modulator comprises a Quadrature VCO (Yusynth VCLFO) and a "Dome Filter" (from J. Haible's Frequency Shifter)

The VCO portion has 3 potentiometers (coarse and fine frequency tuning and modulation CV attenuation), one CV input, 4 outputs and 4 LED indicators.

The dome filter section has one input and two outputs. The outputs are 90º phase shifted from each other. The video shows the waveforms from the VCO and Dome Filter on oscilloscope.

Differences from Yusynth Quadrature VCLFO are the capacitor value (1nF instead of 10nF), and changes in the freq control (fine tuning pot, reduction of the CV input resistor value).

It can operate at audio and sub audio ranges (0.2 to 4000 Hz approximately), but 1V/8ª tracking is only marginal (~2 octaves).

There is no significant differences in the dome filter circuit.

Some examples shown in the video:
Quadrature VCO controlling 4 VCOs, 1V/8ª CV for the Quadrature VCO input coming from the CV Quantizer.*
Frequency Shifter patch using the Quadrature Modulator and two Ring Modulators.*
Adding FM CV to Quatradure VCO (from the Arduino Clock Divider Logic Thing Octal DAC).*

Thanks for watching"