Back in 1975, this pioneering beast became Oberheim's first full keyboard synth, pairing two SEM modules for duophonic play that predated the polyphonic revolution of the Four Voice and Eight Voice.
Each SEM packs two analog oscillators with saw, pulse, and noise waveshapes, PWM, and sync, feeding into a legendary state-variable 2-pole filter that morphs from low-pass to high-pass, band-pass, or notch with creamy resonance that holds onto bass even at max. Dual ADS envelopes shape filter and amp per voice, while a sine LFO, noise, and sample/hold add modulation depth; an 8-step dual-channel analog sequencer lets you drive one SEM hands-free while playing the other on the 37-note keyboard, with unison, left/right priority, polyphonic portamento, and transpose options. Housed in a rugged road-case design with CV/Gate jacks, output mixer, and simple front-panel toggles, it's semi-modular simplicity at its rawest—1 stereo out, no effects, pure subtractive analog fire.
Owners cherish its fat, aggressive tones that echo through classics like early prog rock, though the basic sequencer and lack of memory demand hands-on tweaking that not everyone loves today. A true collector's gem for dialing in those timeless Oberheim sweeps.
