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Korgs poly61 & 61m - Bam - 12-12-2018

Korgs poly61 & 61m

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Poly 61

The KORG Poly-61 (PS-61) is an analogue 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 is 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' VCOs. The Poly-61 also boasted double the amount of patch memory (64 memory positions versus the Polysix's 32), but did not feature its predecessor's on board effects.

Korg (Keio Electronic Laboratories)
Technical specifications
6 voices
2 DCOs per voice
Synthesis type
Analog Subtractive
1 low-pass per voice
1 VCA per voice
1 ADSR envelope per voice
Storage memory
64 patches
61 keys
External control
Poly-61M has MIDI

In 1984 a MIDI version, the Poly-61M was released featuring basic MIDI implementation, however, prior to that, a person could order a factory installed Poly 61 with MIDI in and MIDI out jacket installed on a plate on the rear of the keyboard; simply called Poly-61 with Factory Installed MIDI. The MIDI of the day was quite crude, relatively, with only note on and note off information. No velocity (the amount of force the key is pressed); no Aftertouch, (the programable parameter of what happens after Note Off) and other standards of today was missing.

The Poly-61 offers two DCOs per voice. DCO1 provides sawtooth, pulse, and PWM waveforms. DCO2 has only sawtooth and square.

Filter Edit
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 Edit
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 Edit
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 ┬ÁC'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.

Com Truise
FM Static
Jesse Saunders
Ray Parker Jr. "Ghostbusters"
The Faint
Twenty Four Hours

These are way cool in my book... And great Synths at sometimes a lower price point than more popluar synth of early 80s!! Great features and sound

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