street priceThe Korg Mono/Poly represented in 1981-82 an innovative approach to synthesizer design, offering genuine dual-mode operation as both a monophonic and polyphonic instrument at a very competitive price point. This versatile synthesizer successfully bridged the gap between high-performance monophonic synthesis and accessible polyphonic capability, incorporating several clever design solutions that genuinely enhance its musical performance.
The Mono/Poly showcases the high manufacturing standards typical of Japanese instruments of this era. The casework features dark wood veneer on the sides and front panel, with a plain wooden base board providing a solid foundation. The main control panel consists of black anodised formed aluminium with blue block overlays for section identification and white graphics for clear labeling. While the keyboard construction could be described as somewhat plasticky, the key action itself is excellent — positive and responsive with precisely the right amount of key dip. The control knobs are functional rather than exceptional, but the overall instrument projects an air of quality and thoughtful construction.
At the heart of the Mono/Poly lie four voltage controlled oscillators serving as the main tone generators. The sophisticated control circuitry determines whether these oscillators operate in monophonic or polyphonic mode through a clever assignment system. The mixed signal from all oscillators and the noise source passes through a single voltage controlled filter and voltage controlled amplifier—this shared architecture represents the primary compromise inherent in the pseudo-polyphonic design, but one that Korg has addressed with intelligent control features.
The key assignment system offers five distinct modes controlled by conveniently positioned push-button momentaries located one and a half inches above the keyboard. In Poly mode, the instrument assigns notes intelligently: the first note played routes to VCO 1, the second to VCO 2 (or back to VCO 1 if the first key has been released), continuing this pattern. When four notes are held and a fifth is triggered, VCO 1 is reassigned to the new note. In Unison mode, the control voltage from the last note played routes to all four oscillators simultaneously, creating a thick, powerful monophonic sound.
The Chord/Share mode (previously seen on the Roland JP-4) operates monophonically with all oscillators in parallel when playing single notes. When two notes are played, VCOs 1 and 2 handle one note while VCOs 3 and 4 take the other; three-note playing assigns one VCO per note with the fourth idling. This intelligent resource allocation maximizes the instrument's capabilities.
Chord Memory mode (reminiscent of features found on Oberheim's OB-X, OB-XS, and OB-Xa) allows players to program harmonic relationships. By playing a chord — say a major seventh — and activating Chord Memory, every subsequent single note automatically generates that same intervallic relationship across the oscillators. This transforms the instrument into a monophonic synthesizer with oscillators set at predetermined intervals, far more convenient than manually tuning oscillators to different pitches.
Korg's engineers recognized the inherent challenges of pseudo-polyphonic architecture and implemented thoughtful solutions. The shared VCF and VCA create potential issues when holding one note while playing and releasing another, particularly with longer release times. The Mono/Poly addresses these challenges through two key features:
The single/multiple trigger switch manages filter envelope behavior. In multiple mode, the filter envelope retriggers with every new note, affecting both new and held notes. In single mode, new trigger pulses only generate after the keyboard clears, preventing the new note from affecting the filter envelope of sustained notes.
The Auto-Damp switch solves the problem of oscillator gating to the VCF. Without this feature, releasing a second key while holding another would result in abrupt cutoff, even with long release times set. Auto-Damp sustains the released note until the first key releases, allowing both notes to fade naturally according to the VCA envelope release time. While not a perfect solution, this feature significantly enhances polyphonic performance across various playing styles.
The Mono/Poly also offers polyphonic portamento, providing a slew limiter on the control voltage line to all oscillators for smooth gliding between notes in polyphonic mode.
Each of the four oscillators offers comprehensive waveform selection: triangle, ramp, pulse (with variable width), and pulse width modulated waveforms, available at 16', 8', 4', and 2' pitches. The master tune control provides ±1 semitone adjustment affecting all oscillators, while VCOs 2, 3, and 4 feature individual fine-tune controls (also ±1 semitone). A master detune control shifts the frequencies of VCOs 2 and 4, enabling rich ensemble effects. Each oscillator includes its own level control, and the sound generation network is completed by a dedicated noise source.
The voltage controlled filter employs a steep 24dB/octave low-pass design capable of self-oscillation. It features keyboard tracking and both positive and negative envelope modulation facilities. Both the VCF and VCA have dedicated ADSR envelope generators for precise articulation control.
The modulation system incorporates two low frequency oscillators (termed "modulation generators" by Korg). The first LFO provides sawtooth, ramp up, ramp down, and square waves, controllable via the performance wheel to modulate oscillator pitch, filter cutoff, and oscillator pulse width. The second LFO can control pulse width or serve as the clock source for the arpeggiator.
A particularly impressive feature is the comprehensive cross-modulation and synchronization section, neatly arranged in the center of the control panel. These effects can be preset and instantly activated via momentary buttons, providing sophisticated sound-shaping capabilities that significantly expand the instrument's sonic palette.
The Mono/Poly includes a capable arpeggiator, an increasingly popular feature in synthesizers of this era. Players can hold a chord (using the latch feature if desired), and the control circuitry automatically plays each note in sequence at a rate determined by the second LFO's speed. The arpeggio can automatically expand across the entire keyboard width, with three available patterns: Up, Up/Down, and Down, providing versatile rhythmic and melodic possibilities.
The pitch-bend wheel features a center detent for returning to the initial tuned position—crucial for maintaining accurate pitch. However, the review notes that this detent is somewhat weak and would benefit from strengthening in production models.
The rear panel provides comprehensive connectivity: audio output, headphone output (delivering good, loud monitoring), control voltage and gate inputs and outputs (notably using the volt/octave standard rather than Korg's previous Hz/volt system), VCO FM input, VCF FM input (both for pedal control), portamento footswitch input, and arpeggio trigger input (useful for synchronization with drum machines). This extensive interface capability makes the Mono/Poly highly integrable with other equipment.
Total Jack Sockets: 10
Country of origin / production: Japan
Recommend product to a friend| Usage area | |
|---|---|
| Synthesizer | |
| Usage Design/ Form Factor | |
| With Keys | |
| Archetype | |
| Analogue (A) | |
| Tone Generator / Sound Synthesis | |
| Synthesis Method | Analog Subtractive |
| Oscillators per voice | 1 |
| Waveform/ Spectral form (main generator) | Pulse Width Modulation (PWM) |
| Waveform/ Spectral form (main generator) | Triangle |
| Waveform/ Spectral form (main generator) | Saw |
| Waveform/ Spectral form (main generator) | White Noise |
| Filter | |
| Voltage Controlled Filter (VCF) | |
| Low-pass Filter (LPF) | |
| Amplifier | |
| Voltage Controlled Amplifier (VCA) | |
| Envelope Generator (EG) | |
| Filter | ADSR |
| Amp | ADSR |
| Modulation | |
| Modulation Matrix | 2 source (LFO1, LFO2), 3 destinations (Oscillator Pulse Width, Envelope, Arpeggiator) |
| LFO: LFO Count | 2 |
| Arpegiator/ Portamento | |
| Arpegiator Mode | Up |
| Arpegiator Mode | Down |
| Arpegiator Mode | Up+Down |
| Arpegiator Mode | Latch |
| Arpegiator | |
| Keys | |
| Type | Synth Action |
| Size | 3.5 |
| Number of Keys | 44 |
| Built-in controllers | |
| Pitch Bend Wheel | |
| Modulation Wheel | |
| External controllers | |
| CV in | 2 |
| Power | |
| Power Supply | External |
| Case/ body | |
| Metal&wood | |
| Color | |
| Black | |
| Production start | 1981 |
| Production ended | |
Juno-6 is a 6-voice polyphonic synthesizer launched by Roland in 1982. The starter of the hit series which brought on the market affordable Roland synths of good quality. The synthesis is DCO based though digital control of the analog sound delivers good...
