When Korg released the PS-3100 in 1977, they created something that shouldn't have been possible at the time: a true 48-note polyphonic synthesizer that didn't compromise on sound design. Only around 300 were made, which tells you something about how ambitious and unconventional this instrument was for its era.
The PS-3100 uses a divide-down architecture with twelve master oscillators that generate all 48 notes across the keyboard, each with its own dedicated filter, envelope, and voice circuitry. You get a single oscillator per voice offering triangle, sawtooth, square, and pulse waveforms with PWM control, paired with a resonant 12dB lowpass filter and independent amplitude and filter envelopes. The real magic happens in the resonator section—three voltage-controllable resonant peaks that can boost frequencies between 100Hz and 10kHz, giving you tonal shaping options you won't find on conventional synths. Two modulation generators provide vibrato, tremolo, and modulation routing, while the LFO offers six waveforms including noise sources. An ensemble chorus effect adds thickness to the sound, and there's a sample-and-hold circuit for creating evolving textures.
What sets the PS-3100 apart is its approach to tuning. Those twelve oscillators have independent tuning controls, so you can dial in mean-tone temperament, just intonation, or any alternative scale you want—the manual even explains how to set up heptatonic scales. The semi-modular patch panel gives you CV and gate connectivity for external sequencers and control voltage sources, making it surprisingly flexible for a keyboard instrument. The optional PS-3010 keyboard adds a joystick for real-time expression and different trigger modes. With 49 full-size keys and synth-weighted action, it feels substantial and playable, though the instrument itself is a considerable piece of furniture.
Collectors and experimental musicians have long appreciated the PS-3100 for its unique sonic character and the sheer freedom of true polyphony—you can layer thick harmonic clusters without note stealing. The resonator section in particular has earned a reputation as one of the most distinctive tonal tools in vintage synthesis.
