The EMS Synthi 100 was a large analogue synthesizer made by Electronic Music Studios (London) Ltd. It was released in 1971 and cost £6,500. It is estimated that fewer than 40 units were built.
The Synthi 100 was developed from a combination of three VCS-3 systems, ending up with 12 VCOs, two keyboards (each of it duophonic, making it possible to play four voices simultaneously), and a 3-track 256-step monophonic digital sequencer. Two 60 x 60 matrixes were used to connect the different modules by using patch pins. The keyboard spread could/had to be adjusted, making it difficult to play a tuned temperated scale for a longer time, but allow for alternative tunings easily.
The sound of the Synthi-100 was subtly distinct from the VCS-3. Both filters and oscillators were much more stable in the Synthi-100. The instrument, however, was very sensitive to temperature changes, so it required repeated re-tuning.
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 x 60 matrix patchboards, and a switch button control panel. Three were built.
Also the Vocoder 5000 (Studio Vocoder) was available as a separate module installed into the Synthi 100. It contained a 22 band filter, 22 x 22 matrix patchboard, mic/line inputs, two oscillators and noise sources, frequency shifter, pitch to voltage extractor, and a spectrum display driver.
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