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Back in 1974, this little module kicked off Oberheim's legendary run as one of the first true analog synthesizers, designed as a keyboardless expander to stack killer layers onto your existing synths.

At its heart, two analog VCOs deliver sawtooth and variable-width pulse waves with PWM and sync, feeding into a standout 12dB/octave multimode filter—low-pass, high-pass, band-pass, or notch—that you sweep via a single knob for tones no other synth could match back then. Dual ADSD envelope generators shape the VCF and VCA, while a sine-wave LFO adds modulation depth, all controlled from a compact desktop panel packed with sturdy knobs, switches, and 1/4-inch jacks on the rear, plus two external audio inputs. Housed in a solid steel and plastic (or wood-sided) box around 10x14x7 inches and weighing in hefty, it runs monophonic with one voice output, sequencer compatibility, and pairs perfectly with the external Polyphonic Synthesizer Programmer to store settings for up to eight units.

Vintage players still chase these for their raw, characterful bite—the filter's airy edge and oscillators' warmth shine in everything from leads to basses—though some note the thinner 12dB slope compared to steeper Moog ladders, and tuning can drift like any classic analog. It's a modular vibe in a box, endlessly tweakable for that timeless Oberheim snarl.