Korg mono/poly

A Korg Mono/Poly is a "mono-polyphonic" analog synthesizer manufactured by Korg from 1981–1984. The original retail price was $1400. This keyboard is the sister synth to the Korg Polysix and this model as well as the Polysix are being swiped up for being a great analog alternative to the over-priced Moogs, Prophets, Oberheims, and Jupiters.----
Features to include 4 VCOs with tuning, footage (16, 8, 4, 2), waveshape (triangle, saw, pulse-width, and pulse-width modulated), and amplitude; The first oscillator is the master oscillator as far as fine tuning goes. Two direct modifiers to the VCOs are a portamento control that only effects oscillators 2-4, and a Pulse Width control that goes to cancellation either side of 50% phase symmetry of a square wave; Pulse width can be routed to MG1, MG2, or VCF envelope. There is one independent noise generator with an amplitude control (frequency and shape is modified by the VCF). There is one 24/db octave exponential lowpass VCF with resonance, scaling and invertable envelope control shared across all four VCOs. One VCA envelope with triggering and dampering controls shared across all four VCOs. There are two low frequency modulators: MG1 controls VCO Pitch/Pulse-width, 'EFFECTS' and VCF cutoff; MG2 controls the tempo of the arpeggiator, and Pulse-Width. There is one Arpeggiator with on/off/latch control, up/down/up-down pitch control, and 1/2/full keyboard control (44 notes) The arpeggiator can cycle through each oscillator in POLY mode or all four at a time in MONO. There is an 'EFFECTS' section which includes an amplitude modulator (X-MOD) with hard-sync control, and a frequency modulator with which the frequency of the modulator can be altered by the VCF envelope or MG1. For both modulators there is the option of single modulation of all oscillators, or two carriers, and two modulators (using the VCOs). Controller Interfaces are external inputs for CV/Gate, VCF and VCO mod inputs, arpeggiator, portamento, white noise generator, and the pitch/mod wheels can be assigned to control LFO, pitch or the filter. bender goes to 2.5 octaves +/- for Pitch and full range for VCF cutoff (yow!). There are 5 different oscillator assignment modes: Hold: drones the oscillators until force dampered; Chord Memory (MONO): allows 2-4 oscillators (VCOs) to be set to any arrangement across 44 keys (great for organ or rave chords); Unison (MONO): stacks all 4 oscillators; Unison/Share: This mode defaults to Unison with one note played, but divides the oscillators across the notes as 2 or more are played; Poly is without explanation, and oscillators always play in sequenced order from 1-4.

---

The main drawback of the Mono/Poly is that the 4 VCOs shared one common VCA and VCF envelope, but there were triggering and auto-dampering switches to compensate for the envelope sharing. This synth wasn't so much designed to be a polysynth like it's sister the Polysix (which was manufactured at the same time), but more of an experimental synth with gobs of modulation capabilities and different footages and waveshapes per oscillator. The Mono/Poly also did not include a digital memory like its brother the Polysix, because it's focus was again for experimentation...a comparable model at that time is the Sequential Circuits Pro-1. Other drawbacks are it's chipboard construction on the base and sides of the unit which tend to get damaged easily or allow screws to fall out, and the rubber contacts under the keyboard tend to wear over time resulting in dead keys. As far as circuit reliability, they tend to fare pretty well for most analog synths. If anything should fail, it would be any one of the 4 VCOs - resulting in making its uselessness variable in POLY mode depending on which oscillators have burned out...next to go is usually the filter.

---

Info to know for aficiandos for sound is the filter will self-oscillate (and blow an amplifier) but can also be scaled 1:1 with frequency so that the resonator can act as a 5th oscillator (sine wave). The frequency modulator in the 'EFFECTS' section can be used with the VCF envelope for pitch envelope control. A triangle wave can be used as a sub-oscillator to beef up the bass of the other oscillators. Set a wide-spread chord in chord memory and then use the arpeggiator...and then switch back and forth between poly/chord memory. One cool trick that can be done with the Mono/Poly is using it as a rhythm machine. This can be done by setting the instrument in 'Poly' and setting the different footages of the oscillators and the different waveshapes (triangle actually works best) and then using the ring modulator/frequency modulators with the Arpeggiator. Adjust the envelopes accordingly to percussive settings and fiddle with the cuttoff and noise from time to time to add tone color and for a final trick set the LFO to pitch and set it at a considerable amplitude. Further, the pedal inputs can be routed from synths like the Korg MS-20 so that external oscillators can further modulate above what's already available. Because the VCOs have separate tuning controls they tend to be slightly out of tuning phase no matter how well they're tuned...a little trick to play chords that are in direct tuning phase is to play the notes in a rapid, descending order from high to low...like most analog synthesizers it tends to scale better from high to low then low to high. All in all, it's a perfect alternative to a Moog Minimoog because of its 4 highly-stable VCOs, 4-pole, self-oscillating LPF, gobs of modulations capabilities not present on the mini, and pseudo-polyphony. The editor of this document has played both and prefers the Mono/Poly over the Minimoog...the Mono/Poly with Anglo-Saxton runes on the base of the unit is the one he owned.

Major artists known to use the Mono/Poly include: 808 State, Juno Reactor, The Chemical Brothers, The Orb, and Depeche Mode/Vince Clark.