Korg Mono/Poly Analog Synth SN 373292

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"Original 1980s unmodified classic,

"Four voltage-controlled oscillators (VCOs) and a noise source are routed through a voltage-controlled filter (VCF) and voltage-controlled amplifier (VCA). It can be used as 1) a four-oscillator mono synth; 2) a four-voice paraphonic synth, with voices cycling through oscillators but sharing a VCF and VCA; 3) a shared mode using mono mode for single notes, dual oscillators per note for double notes, otherwise paraphonic mode; 4) a chord memory which results in a mono synth albeit with four oscillators playing notes of up to a four-note chord.

The four VCOs have controls for independent tuning, footage (16, 8, 4, 2), waveshape (triangle, saw, pulse-width, and pulse-width modulated), and amplitude. These are implemented with SSM2033 chips. Portamento may be used for VCO frequency. The noise source has a level control. [1]

The single VCF is a 24/dB octave low-pass filter, with controls for cutoff, resonance, scaling, and invertible envelope control. It can self-oscillate, and be scaled 1:1 with frequency, and thus used as a fifth oscillator. It is implemented with the SSM2044 chip.

There are two envelopes. One is dedicated solely to the VCA. The second in nominally the "VCF envelope" but can additionally control VCO pulse-width, all VCO's pitch, pitch only of VCO's 2 and 4, and frequency modulation amount. The envelopes share controls for single or multiple trigger, and damping.

There are two low-frequency oscillators (LFOs), called "Modulation Generators" (MGs) by Korg. The first has control over waveform and speed, and can be routed to VCO pitch or pulse-width, VCF cutoff, and frequency modulation amount. When controlling VCO pitch, it can control all VCOs; VCO 1; VCO 2, 3, and 4; or VCO 2 and 4. The second only has a control for speed, and can control the arpeggiator or VCO pulse-width.

There is an arpeggiator with on/off/latch control, up/down/up-down pitch control, and 1/2/full keyboard control.

The Mono/Poly includes extensive and significant modulation capabilities between the oscillators, grouped in a section captioned "Effects." These include the abilities to: 1) sync VCO's 2, 3, and 4 to VCO 1; 2) sync VCO 2 to 1, and 4 to 3; 3) to frequency-modulate VCOs 2, 3, and 4 with VCO 1; 4) frequency-modulate VCO 2 with 1 and 4 with 3. Oscillator sync and frequency modulation can be used together. This ability to have 1 master with 3 slave oscillators, or 2 each, is leveraged by the bewildering variety of oscillator subsets that can be controlled with modulation sources and wheel controls.

External inputs and outputs are provided for CV/Trigger, VCF and VCO mod inputs, arpeggiator, and portamento. The pitch bend and mod wheel can be assigned to control pitch of all VCOs; VCO 1 only; VCO 2, 3, and 4; or VCO 2 and 4. The pitch bend range extends to 2.5 octaves for VCO pitch, and the audio range for VCF cutoff."