Greg Burns, the brain behind gregsbrain LLC, is a software engineer with an extensive background in embedded systems, DSP audio processing, and enough hardware engineering to be dangerous. He built his first modular synthesizer while in college but a career in software development got in the way of evolving that interest. Eight or so years ago he got bitten by the Eurorack bug and now has a substantial module collection.
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Opportunity |
Where we are now |
Modular synthesizers have always had a bit of a problem with polyphony. For example, to generate a triad chord requires three oscillators, three VCAs, three envelope generators, and three sets of modulation sources, filters, etc,. Of course, there are some great sampler modules that can produce chords but there are to our knowledge no Eurorack modules capable of generating a triad or seventh chord in real-time from one voice. This looked like both an interesting technical challenge and an opportunity to develop something unique that others might find useful.
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We began developing the xVox Harmonic Pitch Shifter over three years ago. The earliest prototype based on an ST Micro Discovery Board didn't quite have the CPU performance needed to pitch shift more than two voices. We have chosen to use the phase-vocoder algorithm based on the STFT (Short-term Fourier Transform). The updated hardware in the current xVox version can pitch shift four voices. Pitch shifts are quantized to fit within selected scales and there is built in support for triads, 7th chords and chord progressions based on the circle-of-fifths.
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