Polysix

Features
The synthesizer's main features are six-voice polyphony (with unison and chord memory voice assignment modes), 32 memory slots for patches and cassette port for backing up patches, and an arpeggiator.

On its release it was, along with the Roland Juno 6 which was released around the same time, one of the first times a polyphonic analog synthesizer was available at a cost effective price 'for the masses'. It cost about twice as much as the competing Juno 6 but had far more features and 'real' VCOs in place of the Juno's DCOs. It also had on-board patch storage and back up which the cheaper Juno lacked until the upgraded Juno 60 model.

Korg developed the Polysix with an eye on the Sequential Circuits Prophet 5, trying to provide some of the features found on the more expensive synth in a compact, reliable and much cheaper design. While not as powerful, it used SSM2044 4-pole voltage-controlled filters, giving the Polysix a warm, rounded and organic sound.

Although the Polysix only had one oscillator per voice, it also featured built in chorus, phaser and 'ensemble' effects (using a 'bucket brigade' analog delay line design), to provide a fuller sound.

Audio path
The Polysix had a straightforward synthesis architecture. Each voice had one oscillator with sawtooth wave, variable pulse wave, or PWM outputs. The PWM section had its own LFO. In addition, there is a sub-oscillator that allows the addition of a square wave either one or two octaves below the main VCO pitch.

The filter has controls for cutoff frequency, resonance, envelope amount and keyboard tracking. The envelope control has a center zero, letting the user select either a normal or an inverted envelope. The envelope is an ADSR type.

The VCA can be operated from either the envelope or a gate signal.

The mixed sound of all the voices can be sent to an effects section, which offers three modulated delay-based effects (Chorus, Phase or Ensemble setting). This acts to fatten the sound considerably, and was a key feature at the time of release.

Modulation
The LFO (known here as a 'modulation generator') is a simple triangle wave that can be routed to the VCO, VCF or VCA. It has a variable delay before it is triggered.

Like other programmable synthesizers of the era, it had a rechargeable nickel-cadmium battery that powered the memory when the unit was switched off.

Some instruments of its era had begun the move towards digital technology by using DCOs or microprocessor-generated envelopes. The Polysix, however, used a separate analog VCO, VCF and envelope generator for each voice. Whilst this might have benefits for the richness of the sound.

The Polysix keyboard used a light plastic keyboard with conductive rubber contacts.