Korg Polysix (1981–1984)

Name: Korg Polysix
Brand: Korg

Six voices of analog polyphony at a price that undercut nearly everything else in 1981 - and a bucket-brigade chorus that owners still refuse to switch off.

Overview

The Polysix was not the first polyphonic analog synthesizer, and it was not the most powerful. What it was, in 1981, was the one most working musicians could actually afford. At $1,695, it undercut the era's flagship polysynths by a wide margin. Roland's Jupiter-8 cost more than a used car, and digital instruments like the Fairlight CMI were science fiction for anyone without a record deal. Korg saw the opening and took it: polyphony without the premium. The result was a six-voice analog synth that was functional, musical, and affordable.

Six voices, one oscillator per voice. That's the whole architecture, and it's why the price was possible. Most polyphonic synths of the era ran two oscillators per voice, including the Roland Juno-6 that arrived the same year. Korg kept the oscillator count lean and put the difference into modulation and the chorus. The trade shaped the instrument's whole character: less harmonic thickness per note, but a textural depth that owners describe as sounding like it was recorded in a cathedral.

The control surface is all knob-per-function. No menus, no data wheels, no cryptic button combinations. Every parameter has a dedicated control, which sounds like a small thing until you've programmed a synth through a two-line LCD. That immediacy is a large part of why the Polysix earned the following it did.

You can hear its fingerprints on records by Tears for Fears, The Human League, and in the background washes of early Talk Talk albums. Across new wave and ambient music, it was the texture machine of choice for players who valued character over spec-sheet bragging rights.

Key Features

Six Voices, One Oscillator Per Voice

Six-note polyphony from a single oscillator per voice is the defining design decision. Each voice offers sawtooth, pulse, triangle, and square waveforms, with pulse width modulation available from either the LFO or the envelope. The compromise is real. You don't get the stacked, beating richness of a two-oscillator voice. The Polysix makes up for it with movement rather than mass, and the chorus fills in what the oscillators leave open.

Analog Bucket-Brigade Chorus

This is the reason people still hunt for the Polysix. A built-in analog bucket-brigade device chorus gives a warm, swirling modulation that thickens even the simplest patch into something cinematic. Owners report leaving it on constantly, and with it switched off the synth feels oddly naked. It's not a subtle effect, and it isn't meant to be.

24dB/Oct Low-Pass VCF with Self-Oscillation

The voltage-controlled filter is a 24dB-per-octave low-pass design with a cutoff range of 16 Hz to 20 kHz and resonance adjustable all the way up to self-oscillation. That matters in practice. A resonant filter that tips into oscillation turns the Polysix into a sound source in its own right, useful for percussive blips, sine-wave leads, and the filter sweeps that defined the era's records.

ADSR Envelope with Wide Timing Ranges

The envelope generator spans attack from 10 ms to 10 s, decay from 100 ms to 10 s, sustain from 0% to 100%, and release from 100 ms to 10 s. Those ranges cover both snappy plucks and slow-blooming pads, which is the spread the Polysix's reputation rests on. Service documentation for the instrument specifies an attack-time adjustment target of 250 ms ±10 ms under test conditions, with the full attack range confirmed to fade out within 15 to 25 seconds at maximum setting.

LFO with Sample & Hold

The LFO offers triangle, square, and sample & hold waveforms, with a rate range of 0.1 Hz to 100 Hz. It can be routed to pitch, pulse width, or filter cutoff. Sample & hold is the sleeper here. At low rates it gives the stepped, random filter movement that's all over early-'80s electronic records, and it's one of the few modulation options that makes a single-oscillator voice feel unpredictable.

Arpeggiator with Programmable Hold

The arpeggiator runs up, down, and up/down patterns with a programmable hold function that latches the pattern and frees both hands. For its time it was an advanced feature, and the hold function in particular made it usable for live layering rather than just practice-room noodling.

External Audio Input

A single 1/4" audio input lets external signals run through the Polysix's filter and envelope - a drum machine, another synth, whatever's on the bench. That makes the instrument an analog processor as well as a synth, and it's a feature that's kept units in studios long after their keyboard duties ended.

61-Key Keyboard, Non-Velocity

The keyboard spans 61 keys, F to F, and it is not velocity-sensitive and has no aftertouch. That's a genuine limitation. Expressive playing on a Polysix happens through the knobs, the filter, and the chorus, not through touch dynamics. Buyers who need velocity response should look elsewhere or budget for a MIDI retrofit.

Memory and I/O

Patch memory covers 32 user patches and 32 factory patches. Output is a single 1/4" unbalanced jack, with a separate 1/4" headphone output and control inputs for sustain and expression pedals. The chassis measures 980 mm × 348 mm × 110 mm and weighs 13.5 kg. The case is plastic, and it can show wear without affecting performance.

Historical Context

The Polysix arrived in 1981, the same year as the Roland Juno-6, and the two are inevitably compared. The Juno offered a second oscillator per voice and better build quality. The Polysix countered with more hands-on control and that chorus. Where the Juno felt polished, the Polysix felt slightly unpredictable and a little gritty.

It followed Korg's earlier, more experimental instruments like the Lambda, and it preceded the Poly-800, which abandoned knobs for sliders and began the company's move toward cost-reduced, mass-market designs. Polyphony (June 1983, p.41) framed the Polysix's own successor in similar terms, describing the Poly 61 as the best dual-oscillator six-note polyphonic keyboard for the money, but advising Polysix owners not to sell up, noting the considerable difference in sound between the two instruments.

Collectibility & Value

The Polysix is uncommon rather than rare, and its market value has settled in the $800 to $1,500 range as of 2025. Recent eBay completed sales show a wider spread: a high of $1,762, a median of $750, and a latest figure of $1,142, with roughly two units moving per month. Listing prices for working examples have run $1,450 and $1,559, the latter a PS-6 with its original hard case. Replacement parts circulate too - a walnut chassis kit at $259, and the SSM2056 analog synthesizer IC at $24.99 for anyone chasing a dead voice.

Maintenance is the part buyers need to take seriously. Power supply capacitors are prone to degradation, which shows up as noise, hum, or outright failure. The audio path uses electrolytic capacitors that may need replacing after 40-plus years. Pots and switches commonly develop crackles from oxidation. The chorus depends on aging BBD chips that can fail or develop clock noise, which hurts, since the chorus is the whole point. Some units drift slightly in tuning, especially when cold. Battery leakage is a documented problem as well. KiwiTechnics' KiwiSix upgrade documentation shows PCB track damage under the battery, with traces lifted and nearly eaten through.

Insist on a video demo before buying, and check voice tuning evenly across the keyboard rather than just at middle C. Cosmetic wear on the plastic case is largely irrelevant to function. For units that need help, Kenton Electronics sells a MIDI retrofit kit that lets the Polysix be played from a DAW or MIDI sequencer, and a universal retrofit appears on eBay for non-velocity-sensitive synths including the Polysix and Poly 61. KiwiTechnics offers the KiwiSix upgrade. Software emulations exist too. Moodysix is a free software synth that emulates the Polysix, and Behringer's Polyeight is described as copying the Polysix while adding polyphony.

eBay Listings

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