Back in 1975, this compact expander arrived as ARP's clever sidekick, designed purely to beef up the sound of your main synth like the Axxe or Odyssey—often bundled free with an Odyssey that summer.
It's a keyboardless desktop module with a single VCO offering four waveforms: Brass (sawtooth), plus Hollow, Reed, and Fuzz squares with varying pulse widths for tonal bite. A sub-octave divider kicks in extra voices at -1, -2, and -3 octaves to stack thick layers, while a sine LFO adds slow, vibey modulation with rate, depth, and delay controls, plus pitch bend and master tune knobs. Patch its CV in from any 1V/oct synth and mix the mono audio out into the external input—no VCF, VCA, or envelopes means it's all about raw oscillator power in a simple, sturdy metal case.
Vintage players love its no-fuss way of fattening basslines or creating multi-osc growls with a slight detune, though some note the deliberately sluggish LFO and VCO tracking keep it old-school punchy rather than flashy.
