Sequential Circuits Pro One – CPU upgrade and MIDI retrofit

sequential circuits pro one synthesizer
Sequential Circuits Pro One

When we got this Pro One it was acting insane: keyboard playing only one note and/or pitch sliding upwards, loud bursts of noise, weird envelope/triggering behaviors. This synth is unusual for its vintage (early 1980s) in that much of the control voltage for the analog circuitry is generated by a digital CPU, which was hot enough that it burned Darian’s finger when he happened to touch it, badly enough that he still has a blister a week later! So clearly the CPU was bad– and further testing confirmed it. Continue reading “Sequential Circuits Pro One – CPU upgrade and MIDI retrofit”