The EMS Synthi 100 was a large analogue/digital hybrid synthesizer made by Electronic Music Studios (London) Ltd. The ground-breaking analogue and digital engineering was designed by David Cockerell and documented in detail in 1971. The cost at that time was £6,500. The last unit built by EMS was number 30. Afterwards, one final unit was built by Datanomics, who bought assets from EMS when the company folded in 1979. The redesigned unit was sold to Gabinete de Música Electroacústica, Cuenca, Spain.
Developed from an initial concept of three VCS3 systems. The analogue modules alone look more like six VCS3's. Add the 256 digital sequencer circuit cards and the card count is 85 (28 times larger than a VCS3 by circuit board count), with 12 VCO's and eight VCF's Two monophonic keyboards (both keyboards together produce four control voltages and two key triggers simultaneously). The digital sequencer has three (duophonic) layers, 10,000 clock events and 256 duophonic note events. Two 60 × 60 matrixes were used to connect the different modules by using patch pins. The keyboard spread could be adjusted, making it easy to play a tuned equal temperament scale as well as alternative microtonal tunings up to 61 divisions of each semitone.
The Synthi-100 was developed a few years after the first VCS3's. Both filters and oscillators were much more stable in the Synthi-100. There is an oscillator sync function that can sync the 12 main oscillators to each another or from an external source.
The Synthi 100 also had an add-on computer interface known as "Computer Synthi" which contained a PDP-8 minicomputer and 4Kb of random access memory. It featured an LED display, twin digital cassettes, Two 24 × 60 matrix patchboards, and a switch button control panel. Only three were sold.
Also the Vocoder 5000 (Studio Vocoder) was available as a separate module installed into the Synthi 100. It contained a 22 band filter, 22 × 22 matrix patchboard, mic/line inputs, two oscillators and noise sources, frequency shifter, pitch to voltage extractor, and a spectrum display driver. The first one to be used in the USA was purchased by Stevie Wonder
The Synthi 100 owned by Jack Dangers can be heard being used extensively on electronica group Meat Beat Manifesto's album R.U.O.K.?. Many photos from that album's CD sleeve are close-up photos of the Synthi 100's control panels and displays. It was claimed that his unit was the only one still in working condition at that time.
A Synthi 100 (formally from Melodia Radio) is on display at the National Music Centre in Calgary, Canada. Until recently The Music Department of the University of Saskatchewan, in Saskatoon, Canada, also possessed a Synthi 100.
The BBC Radiophonic Workshop already had an informal relationship with EMS which went back as far back as 1964 and were familiar with products being developed. They took delivery of an EMS Synthi 100 modular system in 1970 which had been modified to BBC specifications, dubbing it the "Delaware", after the name of the road outside the studio. Their composer Malcolm Clarke was one of its most enthusiastic users. One of the more notable scores he produced with the Synthi 100 was the incidental music for the 1972 Doctor Who serial The Sea Devils.
The first classical electronic music LP album generated exclusively on the Synthi 100 was released by Composers Recordings, Inc. in 1975. Called "American Contemporary-Electronic Music" (CRI SD 335), it featured full LP side lengths of music from Barton McLean (Spirals) and Priscilla McLean (Dance of Dawn).
The WDR Electronic Music Studio ordered a Synthi 100 in 1973, and it was delivered the next year It was used by Karlheinz Stockhausen in Sirius (1975-77), by Rolf Gehlhaar for Fünf deutsche Tänze (1975), by John McGuire for Pulse Music III (1978), and by York Höller for Mythos for 13 instruments, percussion, and electronic sounds (1979-80).
The University of Osnabrück, Germany, has a Synthi 100 variant labelled "Synthi 200" (since 1981). The same variant was bought in 1973 by the Bulgarian National Radio for the electronic music studio of Simo Lazarov.
IPEM, the musicology research center and former electroacoustic music production studio of Ghent University also owns a restored and working Synthi 100. It was acquired in the mid 1970s. Recently it was used by Soulwax, an electronic music band.
Eduard Artemyev, Yuri Bogdanov and Vladimir Martynov used the Synthi 100 owned by Soviet label "Melodia" for their record "Metamorphoses - Electronic interpretations of classic and modern musical works". Also Lithuanian composer Giedrius Kuprevi?ius for their rock-oratorio "Labour and Bread" (1978) and Estonian composer Sven Grünberg for the soundtrack of Hukkunud Alpinisti hotell (Dead Mountaineer's Hotel) (1979) as mentioned in the title sequence of the movie.
A Synthi 100 has been part of Radio Belgrade's Electronic Studio since the 1970s, but was in a non-functional state for the 15 years leading up to October 4, 2017, when it was restored. It is serial number 4. 
For synchronization of the oscillators use White pins (2.7k?). 220.127.116.11 - The synchronization of an oscillator
#353: EMS, Synthi 100 - 2 manual (1971-78, S/N 3009) Instrument - Synth