This week an odd topic: analogue synthesis. In the 1970s and early 80s, Yamaha was a leading manufacturer of analogue synthesisers. Where the MiniMoog is the archetype of the monophonic (one voice) keyboard synthesiser, the Yamaha CS80 is the undisputed ‘mother of polysynths’, regarded as the most impressive achievement in audio engineering in the seventies.

The origin of the CS series was the design of synthesis modules for the GX1 Electone organ early in that decade, applied also in the SY-1 and SY-2 monophonic synthesisers. These instruments used discrete component-based synthesis modules for VCO, VCF, VCA and envelopes, moulded in a thick epoxy harness for stability, causing the units to be heavy – the GX1 weighed 300 kilograms.

After the GX and SY models, the discrete component-based synthesis modules were developed into a series of Yamaha IG series integrated circuits, produced for Yamaha by Mitsubishi in the 70s and early 80s. A remarkable feat, with only competitor Roland also producing proprietary analogue synthesis chips, where most other manufacturers of analogue synthesisers in the late seventies and eighties used general-purpose synthesis chips by SSM and Curtis Electro Music (CEM).

With one exception, all Yamaha CS series synthesisers were built with proprietary analogue and digital circuitry, no microprocessors were used. This makes the polyphonic CS50 (4-voice), CS60 and CS80 (8-voice) all the more exceptional – achieving full voice polyphony without a CPU takes a lot of hardware engineering, with Yamaha being the only company at that time with the resources to pull it off. Although the poly CS models used the IG series chips they were still heavy, with the CS80 weighing 100 KG – also due to the unique balanced velocity-sensitive keyboard with polyphonic after-touch.

As a result of Yamaha’s very strict production quality management, many CS80’s survived 40 years of usage, and are still in use today. The most notable user of the CS80 was the Greek composer Vangelis, check out his albums Beaubourg, Spiral, China, and, of course, the soundtrack to Blade Runner.

In the early 1980s, microcomputer technology was adopted by synthesiser developers to build programmable polyphonic instruments, making use of the microcomputer’s memory to store settings. The pioneering synthesiser manufacturer Sequential Circuits was the first to launch a mass-produced CPU driven model, the Prophet 5, soon followed by the Roland Jupiter 8, Oberheim OBX, Moog MemoryMoog and Yamaha CS70M, all making use of the same Z80 microprocessor.

The CS70M, however, was one of a kind. It had pioneering features such as digital faders (yes, really, the faders produced a 5-bit code instead of a voltage), a magnetic strip-based external memory, fully analogue-yet-programmable dual channel synthesis and, to top it all off, a polyphonic sequencer. It’s as if the engineers pulled out every trick they could think of for their last analogue baby...

The CS70M would be the last of Yamaha’s analogue synthesisers, as in 1983 the fully digital DX7 was launched, changing the world of popular music for the next decade. But that’s another story for another blog episode...