The Sequential Circuits Pro One is a wicked little monosynth! It comes from the same period and genre as the Roland SH-101 and Moog Prodigy.
The Pro One was basically Sequential's attempt at taking their legendary Prophet 5 poly-synth and packing it into a compact, inexpensive, monophonic analog synth! It has two VCOs, a great 4-pole lowpass filter, two ADSR envelopes (one for filter), and a compact three-octave keyboard. With a Pro-One, you can easily create punchy analog bass-lines and leads or quirky analog synth effects.
The Pro One is an extremely flexible synth with lots of modulation possibilities (ie: the filter, VCO B and LFO can modulate VCO A or B frequencies or pulse widths, or the VCF). There's also an onboard sequencer, something common on many Sequential synths but not often found on other monosynths of the time. It is very basic, however, storing only two patterns and up to 40 notes max. Also, only pitch info is recorded (and in step time only); you can not assign a note duration to any notes. So it's basically a short melodic sketch-pad...but useful. Also onboard is an arpeggiator which has UP and UP/DOWN patterns.
The Pro One is relatively simple and intuitive to use, fun, educational and responsible for some of the coolest and hardest basslines in electronic music today!
This particular Pro One has been serviced, stripped and cleaned with all contacts cleaned, everything works as it should. It has the original contact keyboard, which that can easily be replaced with a higher-grade fatar keyboard from here: https://
