Korg Vintage Poly61 61 Key Polyphonic Synth with A&S Case Used

Left in the closet for years, it still plays and comes with a Flight Case from A&S caes. In excellent physical condition

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 , in place of the Polysix' more retrograde VCOs.

The Ploy61 also retained the arpeggiator of the Polysix. The Poly-61 can provide cool gritty basses or trippy analog sounds and fx.

Also added is the familiar Korg joystick, which can be used to modulate the VCO or the VCF. However, its filter only has 7 steps of resonance and is not as fat as the Polysix's filter.

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.

Modulation

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.