Library for QCVG (Quad Control Voltage Generator)
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The QCVG (Quad Control Voltage Generator) is a hardware and software package designed, built, and developed by Reuben Son for implementing computerized control of an analogue modular synthesizer. On the hardware side, the QCVG is comprised of an Arduino Nano microcontroller interfaced to a pair of dual-DAC chips, which provide four channels of 0-4V CV (control voltage), and four trigger outputs (for triggering envelope generators in the synthesizer). Each CV output may be patched into an oscillator to control its pitch, and the trigger outputs are to be patched into envelope generators to control the articulation of notes through a voltage-controlled amplifier (VCA). The present software for the QCVG is still under development and a small production run of the hardware is planned for the future.

The following demo was recorded using the sample sketch provided -


First developed in the 1960s, modular synthesizers have revolutionized electronic music production, marking a radical shift from the tape music that came before. However, modular synthesis in the analogue domain remains expensive (due to the requirement of many dedicated modules) and clumsy to program (management of multiple voices and polyphony are difficult). The development of the QCVG (Quad Control Voltage Generator) was motivated by the desire for implementing simple compositional rules to generate the rhythmic and tonal structure of music within the modular synthesis environment. Usage of the QCVG allows the algorithmic control of music to be implemented digitally, but leaves the control of timbre and other musical details to be shaped in realtime via direct interaction with the rest of the modular synthesizer (i.e. via control of envelope generators, filters, intermodulation). The GROOVE system designed by Max Matthews at Bell labs in the early 1970s provides an interesting historical precedent to this scheme, in coupling analogue sound design with computer control. The GROOVE system was famously used by Laurie Spiegel in her album, 'The Expanding Universe'.