Last update: 8 March 2022

The Yamaha CS80

So, you want a synth that will make everybody sit up and take notice? Well... how about tracking down the world's first fully programmable polysynth? Provided that you're prepared to devote half your studio to a keyboard that weighs nearly half a ton, and the other half to its huge dedicated speakers, you're looking for one of the seven or so examples still known to exist. You're after a Yamaha GX1.

Released in 1975, the GX1 was not just back-breaking, it was ground-breaking too. Each of its 36 voices had a dedicated analogue oscillator plus two filters and two envelope generators. You built patches from two of these voices, and you could play them with eight-voice polyphony from each of the twin five-octave manuals, monophonically from a velocity- and pressure- sensitive 'solo' manual, and from the double-octave bass pedals. There were 70 voice memories from which you could derive 135 individual patches and almost limitless combinations. There was a primitive analogue drum machine, and some basic internal effects. With abundant layering, filtering, modulation, and performance facilities, the GX1 was so flexible that no other synthesiser came close. Mind you, no other synthesiser came close to its cost either and, at approaching £50,000, it's hardly surprising that Yamaha sold very few. Rumour has it that only twenty or so saw their home shores recede into the distance. Those that did ended up in prestigious hands indeed. Abba, Stevie Wonder and Led Zeppelin's John Paul Jones were all aficionados, but perhaps the most famous was Keith Emerson's, which featured prominently on ELP's Works video, and formed the basis of the evergreen Fanfare for the Common Man. Still, Yamaha didn't seem to mind the meagre sales, and why should they... the GX1 proved to be the test-bed for a much more successful, portable version. Weighing in at a mere 100Kg, and costing just £4,950, this offered many of the features of its illustrious progenitor. It was the CS80, and Yamaha sold over 2000 of those.

Fanfare for the uncommon synth

To appreciate the major difference between the CS80 and lesser contemporaries such as the ARP Omni, the Korg PE1000 and the Polymoog, you have to take a brief look at the number of complete synthesiser circuits (including oscillators, filters and envelopes) that each instrument possessed. Synthesisers are only truly polyphonic if each note is shaped individually. Nowadays we take for granted the idea that, if you play a second note, it follows the same tonal and volume development that any previous note exhibited. Indeed, the cheapest synth modules will now articulate 64 notes or more correctly. But in the 1970s this was not the case, and all of the competitors mentioned (and a number of later quasi-polyphonic synths such as the Korg Trident, Roland RS505 and ARP Quadra) incorporated just a single filter and a single envelope, so any subsequent notes began at whatever stage the first had already reached. This means that, while early Moogs, ARPs and Korgs were polyphonic in the sense that you could press lots of notes simultaneously, their limited architectures meant that they couldn't shape new notes correctly if others were still depressed.

The CS80 changed all of that. Each of its sixteen GX1-derived voices was a self-contained monosynth with dual contour generators, resonant high-pass and low-pass filters, and its own response to velocity and aftertouch. Every voice was, therefore, a powerful synthesiser, with facilities exceeding those of most monosynths. The CS80 also boasted a fabulous ring-modulator, chorus and vibrato and, in addition to 22 presets, had four memories to take advantage of it all. Furthermore, its wooden keyboard was superb, offering an excellent weighted action (which even the GX1 lacked), and additional features such as its ribbon controller made it more expressive than most monosynths. This was heady stuff, and years ahead of its competition so, despite its still considerable price tag, the CS80 was a huge success. Nowadays, a list of its endorsees reads like a 'who's who?' of the late-70s: Vangelis, Eddie Jobson, Tomita, Patrick Moraz, Tangerine Dream, Peter Vetesse, Duncan Mackay, Don Airey, Ken Freeman, Stevie Wonder, Kate Bush, and Ultravox... to name but a few.

So everything was perfect at the polysynth party? Well... no. While a well-treated CS80 sounded wonderful and would generally be reliable, life on the road could turn it into an extremely heavy, expensive-to-maintain, pain in the posterior. Remember, these were the days before the affordable micro-processors and purpose-built silicon chips (ASICs) used in modern synths, so every one of the 16 oscillator circuits, the 32 filters and 32 envelopes, the controllers, and the programmers, needed space on a circuit board. Well, on one of 35 (!) circuit boards to be precise. The result was heat - lots of it - and hot analogue oscillators go out of tune. As do very cold ones. The problem was sometimes so extreme that merely opening the case to adjust the tuning could cause the instrument to go out of tune. As did closing it again. And it didn't even have an auto-tune function!

Nevertheless, everybody persevered. Long after the appearance of the Prophet 5 and the Oberheim OB-X, the CS80 remained the instrument of choice for many top players. The depth and quality of its sound - which many would say has never been equalled, let alone surpassed - made almost any inconvenience worthwhile. With a CS-80, a Minimoog, and a Hammond organ, you were at the top of the tree.

Still you turn me on

Nowadays, finding a CS80 in mint condition (or, more to the point, affording it) is almost impossible, and those that appear for sale can be tatty and potentially unreliable. But let's suppose that you manage to find a good one. How are you going to hook it into a modern studio? You could add MIDI, but that entails more circuitry, and carries its own risks. Alternatively, you could set up the sounds exactly as you want them and sample them. Unfortunately, and in common with other vintage synths, sampling the CS80 fails to capture the essential quality of the instrument. Without the individuality and inconsistencies of the sixteen voices and the expression that comes from its poly-pressure-sensitive wooden keyboard, the results are never quite the same.

So why buy one? After all, you'll never be able to carry it to a gig on your own, and it might be out of tune before you get there anyway. You can't easily hook it up in your MIDI studio, and sampling it doesn't work. To make matters worse, many CS80 spares are hard to obtain. The reason, of course, is to experience the power and quality of a truly impressive analogue synthesiser. The CS80 was flexible, great fun to program, delicious to play, looked an absolute treat, and was the only synth ever to recapture the depth and sound of the GX1.

Copyright © Gordon Reid.

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