Korg Poly-61
 Poly-61 | |
| Manufactured by | Korg |
|---|---|
| Dates | 1982-1986 |
| Technical specifications | |
| Polyphony | 6 voices |
| Timbrality | Monotimbral |
| Oscillator | 2 DCOs per voice |
| LFO | 1 |
| Synthesis type | Analog Subtractive |
| Filter | 1 low-pass per voice |
| Attenuator |
1 VCA per voice 1 ADSR envelope per voice |
| Memory | 64 patches |
| Input/output | |
| Keyboard | 61 keys |
| External control | Poly-61M has MIDI |
The KORG Poly-61 is a programmable polyphonic synthesizer released by Korg in 1982, a digitally controlled successor to the Polysix. It was notable as it was the first Korg synthesizer to feature a pushbutton user interface, dispensing from the Polysix's knobs and switches. In 1984 a MIDI version, the Poly-61M was released featuring basic MIDI implementation.
Audio path
Oscillators
The Poly-61 offers two DCOs per voice. DCO1 provides sawtooth, pulse, and PWM waveforms. DCO2 has only sawtooth and square.
Filter
The filter has the typical controls for cutoff, resonance, keyboard tracking and envelope amount. Some of these are rather limited by the poor parameter resolution. Keyboard tracking is simply "on" or "off" for example, and resonance and envelope level (here labelled "EG Intensity") have only 8 values.
Output
The final component in the audio path is a VCA. It can be driven by the envelope generator or a CV/Gate pulse.
Sound Processor
NEC D8049C - 8 bits, 11 MHz (max.), 40 pins (DIP), Supply Voltage = 5V
There is 2 of them on the CPU board (KLM-509), one is a Programmer and the other is an Assigner.
The 8049 has 2 KB of masked ROM as well as 128 bytes of RAM and 27 I/O ports. The µC's oscillator block divides the incoming clock into 15 internal phases, thus with its 11 MHz max. crystal one gets 0.73 MIPS (of one-clock instructions). Some 70% of instructions are single byte/cycle ones, but 30% need two cycles and/or two bytes, so the raw performance would be closer to 0.5 MIPS. Minimum Instruction Length of 8 bits and Maximum Instruction Length of 16 bits.[1]
Modulation
Envelope generator
The envelope is an ADSR type. All parameters can be set to any of 16 values. The chip used are the SSM-2056 and there are 6 of them. These are voltage controlled (analog).
LFO
The LFO (known as a 'modulation generator' on the Poly-61) is a simple triangle wave that can be routed to the DCOs or VCF. It has a variable delay before it is triggered
Notable Users
- FM Static
- The Faint
- Com Truise
- Heizraum Studios
- Kanjo
Differences from the Korg Polysix
Although similar in some ways, there are numerous differences between the two:
- Many parameters on the Poly-61 have limited resolution of 8 steps, whereas Polysix parameters have 256 step resolution.
- The Poly-61 has DCOs versus VCOs on the Polysix.
- The Poly-61 has two oscillators versus one on the Polysix.
- The Poly-61M has basic MIDI implementation.
- The Poly-61 has 64 memories, instead of 32 on the Polysix.
- The Polysix has an analog effects board, whereas the Poly-61 has no effects.