Dates 1982-1986 Timbrality Monotimbral LFO 1 | Polyphony 6 voices Oscillator 2 DCOs per voice | |
Manufacturer Korg (Keio Electronic Laboratories) | ||
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.
Contents
In 1984 a MIDI version, the Poly-61M was released featuring basic MIDI implementation.
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.
Embedded processors
NEC D8049C - 8 bits, 11 MHz (max.), 40 pins (DIP), Supply Voltage = 5V
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.
Envelope generator
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.
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.