MSK 013 release

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Complex VCO takes the harmonious path

TORONTO, Ontario - July 13, 2020 - North Coast Synthesis Ltd., Toronto-based manufacturer of electronic musical instruments, has combined through-zero phase modulation, wavefolding, and stereo image generation in its new complex voltage-controlled oscillator for Eurorack synthesizers. The module, called the Middle Path VCO for its goal of bridging the gap between East Coast and West Coast synthesis styles, features a unique waveshaping section that can cross-modulate the outputs of its two built-in oscillator cores, or process external signals.

The two triangle oscillator cores in the module can be used separately or synchronized. Each has multiple output waveshapes suitable for subtractive East Coast synthesis techniques, especially in combination with North Coast's popular subtractive filter modules.

"I used some expensive chips in the dual exponential converter for this module," says North Coast module designer Matthew Skala. "A premium transistor array and a couple of analog multipliers. That let me put the frequency-controlling transistors for both cores on a single chip, driven by the same references. It's meant to keep them tracking each other as accurately as possible, either for musical harmony if you're using them as two East Coast voices, or to keep the timbre precise when one is modulating the other."

That modulation is done in the Middle Path's unique waveshaping section, based on the sine shaper invented by Barrie Gilbert in the 1980s, extended to provide quadrature outputs. Either oscillator can drive the phase backwards, providing through-zero spectral effects even though the oscillator cores only run forwards.

"It's a different way of doing through-zero," explains Skala. "Instead of modifying the oscillator cores, we're creating negative frequencies in the modulation section. That fits in better with the other West Coast kinds of things the sine shaper can do, including stereo image creation through the quadrature outputs."

North Coast sells the MSK 013 Middle Path VCO from its own Web storefront for $660 Canadian including shipping (assembled module), or $450 for a do-it-yourself kit.

MSK 013 Middle Path VCO