|Oscillator||2 DCOs per voice|
|Synthesis type||Analog Subtractive|
|Filter||1 low-pass per voice|
|Attenuator||1 VCA per voice
1 ADSR envelope per voice
|External control||Poly-61M has MIDI|
The KORG Poly-61 is a programmable polyphonic synthesizer released by Korg in 1982, as a successor to the Polysix. It was notable for being Korg's first "knobless" synthesizer - featuring a push button interface for programming, dispensing from the Polysix's knobs and switches. The Poly-61 also moved to a hybrid tone generation system, using digitally controlled analog oscillators or DCO's (Roland's Juno-6 had made the same leap the previous year), in place of the Polysix' more retrograde VCOs.
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.
There are 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, but 30% need two cycles and/or two bytes, so raw performance is closer to 0.5 MIPS. The Minimum Instruction Length is 8 bits and the Maximum Instruction Length is 16 bits.
The envelope is an ADSR type. All parameters can only be set to one of 16 values.
There are 6 SSM-2056 analog envelope generator chips used in the Poly 61 each being controlled by discrete 4 bit D/A converters. This means there are only 16 possible settings for each of the ADSR parameters.
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.
- "POLY-61 Programmable Polyphonic Synthesizer (1982-11)". Korg Museum, Sound Make Up. Korg Inc.