If you're reading this, you probably know that the Yamaha CS-80 is one of the most coveted polyphonic analog synthesizers ever created. When it was originally released in 1976, there was nothing like it on the market - with features like eight-voice voice assign polyphony, velocity and aftertouch sensitivity, and a massive sound, it truly was a flagship in sound quality, feature set, and build quality. The CS-80 became a legend for its use by Vangelis in the classic sci-fi flick Blade Runner, creating immense and dreamy warbling soundscapes that liberally made use of its very musical and controllable ring modulator. The CS-80 set a new standard in real-time control, and Vangelis took great advantage of the CS-80's bank of arced paddle-style performance controls, as well as the aforementioned keyboard velocity and aftertouch sensitivity.

With DSP code programmed by award-winning synthesizer designer Mark Barton, Cherry Audio's GX-80 emulates all of the sonic and control characteristics of the CS-80 with outstanding accuracy. Mark's extensive research of the original CS-80 schematics and design led him back to the CS-80's predecessor, the mighty GX-1, aka "The Dream Machine" - truly one of the most impressive synthesizers ever conceived.

In the 70s and 80s, Yamaha often tested out new technology by creating a large and expensive flagship instrument. Released in 1974, the GX-1 represented the absolute cutting edge of organ and analog synthesizer technology. It was produced in extremely limited numbers (estimated around 20), and cost $50,000 (that's a comfortable house in the early 70s). This put it far out of reach for most musicians, but it was famously used by Stevie Wonder, Keith Emerson, Benny Andersson of ABBA, and a little later, by John Paul Jones of Led Zeppelin.

GX to CS

It's important to remember that like other Japanese manufacturers, Yamaha arrived in the synthesizer market via production of home organs. Korg, Roland, and Yamaha all produced small monophonic synthesizers intended as solo instruments to be placed atop a home organ. Seeing the expressive limitations of then-current "divide-down" organ technology, Yamaha used their basic SY-1 mono analog synth as the building block upon which to create the GX-1, which combined analog synthesizer voicing technology with a user interface and poly capabilities of a large multi-manual organ and pedalboard. Unlike the CS-80, the GX-1 by itself was strictly a preset instrument. Though it had no onboard synthesizer parameter controls, its analog synthesizer voicing could be programmed using an external hardware programmer box, and user sounds could then be saved as presets to cartridges through an almost comically elaborate procedure.

Though their outward appearances are radically different, both instruments are very similar under the hood. Both feature a voicing architecture based on "ranks," wherein each rank is a complete synthesizer voice consisting of an oscillator, highpass and lowpass filters, a noise generator, a sine wave oscillator, envelope generators for the filter and VCA respectively, and a VCA. The CS-80 includes two of these voice ranks, each capable of playing up to eight independent polyphonic notes - a total of 16 synth voices under the hood.

The GX-1 features four of these eight-note poly voice ranks, assignable across two keyboards, plus a single "lead synth" voice rank with its own mini three-octave keyboard, and finally, another voice synth voice rank for the pedalboard, for a grand total of 34 (!!!) full synth voices... essentially like having two complete CS-80's and then some. It should go without saying that with all these layers of voice ranks, the GX-1 was capable of beautifully large animated tones. The nature of its synth voice, particularly the cascaded highpass/lowpass filter arrangement and their unique topology, resulted in a sound quite different than the familiar fat Moog ladder filter sound, resulting in a uniquely sophisticated midrange-forward tonality.

We should also mention that both instruments were highly innovative in their "voice-assign" polyphonic arrangement. We take the ability to play multiple individually articulated notes for granted, but this was all but unheard of in 1974. Besides a few custom rigs, there were no other instruments on the market that could assign keys to a finite number of synthesizer voices - the impact of this innovation cannot be overstated (otherwise we'd all still be playing Farfisa organs and string machines). By the time the CS-80 was released in 1976, the only other voice-assign poly synths on the market were the Oberheim Two- and Four-Voice instruments, and these were far more finicky to use.

That said, Yamaha's approach to preset sounds was downright archaic. The CS-80 included 22 permanent factory presets, divided between the two voice ranks, and allowed "storage" (to use of the term loosely) of four additional sounds (two per rank) via tiny slider pots under a hinged panel. These sliders were miniaturized versions of all voicing controls, and selecting the Tone Selector Memory 1-4 buttons simply swapped out the main panel voice controls for the chosen mini slider set. For those of you with an electronics background, you can only imagine how many failure-prone 4000-series logic switching chips this feat entailed! The GX-1 used a conceptually similar system, but all of its sound presets were defined by external cartridges full of tiny trimpots. Unlike the CS-80, these were too tiny to edit sounds with in real-time, so Yamaha came up with a pair of impressively elaborate external programming boxes whose operation is so ridiculous as to be pure comedy.

To be fair, the GX-1 was really conceived as an organ on steroids moreso than a purely user-programmable synthesizer. Besides its beautifully layered sound, the GX-1 had a fantastically innovative array of performance controls, including velocity- and pressure-sensitive keyboards, a knee expression lever, swell pedals, and a pitch bend ribbon.

GX1+CS-80 = GX-80

As its name implies, the Cherry Audio GX-80 is not purely a CS-80 emulation. Though the Yamaha GX-1 and CS-80 are similar under the hood, the GX-1 is roughly equivalent to two complete CS-80's in one (real big) box. Additionally, the GX-1 oscillator section featured a pulse wave output with an adjustable highpass resonator and a sawtooth wave output with its own dedicated bandpass resonator (these are in addition to and in parallel with the standard pulse and sawtooth wave outputs), allowing numerous additional sound colors. It's particularly useful for simulating the resonances of traditional string and wind instruments.

The Cherry Audio GX-80 incorporates all of the GX-1's extra features. Single and Dual buttons allow GX-80 to operate like the standard two-rank CS-80; the GX-1's additional two voice ranks are added when Layer Mode is set to Dual. We've also added a keyboard split mode, allowing splitting of the lower and upper ranks across the keyboard. The GX-1's additional filtered waveform outputs are also included, as well as its octave-up triangle wave and the ability to invert filter envelope control. GX-80 also includes CS-style filters as well as the GX-1's unique filter topology. All GX-1-unique parameter controls are orange to distinguish them from standard CS-80 control parameters.

GX-80 has been super fun to develop, and Mark Barton's work on its audio path has been exemplary. We hope you enjoy this monster synth as much as we do!

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