When Korg released the Mono/Poly in 1981, they solved a problem nobody quite knew they had: what if you could stack four oscillators into a single voice, or spread them across four independent notes? It was the only monophonic synth on the market with an integrated quad-VCO design, and it arrived the same year as the Polysix, offering a completely different approach to synthesis.
The heart of the Mono/Poly is its four voltage-controlled oscillators, each capable of producing triangle, sawtooth, pulse, and pulse-width modulated waveforms. You can detune and adjust the octave and level of each VCO independently, while the first oscillator handles master tuning duties. A 24dB-per-octave resonant lowpass filter shapes the sound across all four oscillators, with dual ADSR envelopes controlling both the filter and amplifier. Two modulation generators provide movement—the first offers multiple waveforms and targets pitch, filter, and pulse width via the mod wheel, while the second is dedicated to pulse-width modulation and arpeggiator tempo.
What really sets the Mono/Poly apart is its Effects section, which combines oscillator sync and cross-modulation in flexible configurations. You can run all four oscillators as a single dense monophonic voice, or split them into two pairs that modulate each other for duophonic play. The integrated arpeggiator cycles through oscillators in poly mode or all four at once in mono, with selectable range and direction. The compact 44-key wooden-panel keyboard includes 41 potentiometers for real-time tweaking, plus CV and trigger inputs for external sequencing and modulation.
The Mono/Poly developed a devoted following among sound designers and experimentalists who appreciated its unconventional approach to polyphony and its ability to generate everything from lush, detuned unison textures to wild cross-modulated tones. While it never achieved the mainstream success of Korg's other classics, its unique paraphonic architecture and powerful oscillator design made it a studio staple for those seeking something genuinely different. The synth weighs 12 kilograms and draws 28 watts, making it reasonably portable for a four-oscillator analog machine.
