OnChip Systems

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Curtis Electromusic Specialities logo.png
OnChip Systems formerly known as Curtis Electromusic Specialities.

The company

After working for four years at Interdesign, Inc. Doug Curtis went on to found Curtis Electromusic Specialties in 1979.[1] He did this specifically to design and manufacture integrated circuits for music synthesizers. Curtis Electromusic Specialties manufacturered a wide variety of ICs, many of which incorporated an entire synthesizer functional component, for example, the CEM3340, which contained a complete voltage controlled oscillator. By using chips from Curtis (and its competitor, SSM), synth manufacturers were able to considerably reduce the size of their circuitry. This (along with the advent of inexpensive microprocessor control) is what led to the wave of polyphonic analog synthesizers in the 1980s. By using the Curtis and SSM chips, manufacturers were able to shrink the size of their circuitry to where it could all fit in a package no larger than what was necessary to also house a keyboard and control panel.[2]

Later developments included more highly integrated circuits such as the 3389 signal processor and the 3396 synth-on-a-chip. The further miniaturaization led to the creation of rackmount synthesizers, played via MIDI from a master keyboard, and saving performers both money and space.[2][3]

OnChip Systems

In 1988 with the advent of digital technology and software, Doug Curtis broadened his focus beyond synthesizers forming OnChip Systems and did no further design work on music synthesis products, except for occasional consulting for synth manufacturers until his premature death in 2007. Several more patents in his name are assigned for chips designed into various commercial products.[2][4][5]

In 2016 OnChip Systems re-released the 3340, in response to Coolaudio's V3340 re-design of the part to the same specifications.[6][7]


Latvian brand alpharzpp https://www.alfarzpp.lv/ produces the AS3310, AS3320, AS3330, AS3340, AS3345 and AS3360 in DIP and SMD packages.

The designs

CEM ICs have part numbers of the form "33nn", and synth designers and techs often speak these part numbers without further attribution.[2] De-encapsulated (defective) CEM ICs are obviously bipolar arrays, although Interdesign or Ferranti die marks are missing. They exactly match the 1980 databook 201 Analog IC Designs from Interdesign.[1]



Synthesizers using CEM ICs


DIY projects


See also


  1. ^ a b Pictures of dead CEM chips at Stromeko Synth World
  2. ^ a b c d Curtis Electromusic, Electronic Music wiki
  3. ^ About the Company, Curtis Electromusic
  4. ^ Doug Curtis, Curtis Electromusic
  5. ^ About the Company, Curtis Electromusic
  6. ^ Curtis Electromusic Specialties, Facebook, 5 June 2016
  7. ^ Curtis Family Speaks Out Against Behringer Synth Clone Plans Using CEM3340 by Rounik Sethi, Ask.Audio, 21 Mar 2017
  8. ^ CEM data sheets
  9. ^ a b Various schematics
  10. ^ Curtis Electromusic Product Overview
  11. ^ What chip do I have in my synth? at www.synthtech.com
  12. ^ a b Build a better music synthesiser by Thomas Henry, Tab Books Inc, 1987, ISBN 0830627553
  13. ^ Curtis Electromusic Customers and Instruments
  14. ^ Synthesizer Database by Moogulator
  15. ^ CEM chips in Doepfer Modules by Pierre Serné, 28 Feb. 2012
  16. ^ MIDIbox 3396
  17. ^ Digisound 80 Synthesizer Modules
  18. ^ Wikipedia:CEM and SSM chips in synthesizers

External links

Data sheets

CEM3310, CEM3310 long,CEM3312, CEM3320, CEM3320 long, CEM3328, CEM3330, CEM_3330-3335 long, CEM3340, CEM_3340-3345 long, CEM3350, CEM3360, CEM3365, CEM3371, CEM3372, CEM3374, CEM3378, CEM3381, CEM3389, CEM3391, CEM3394, CEM3396, CEM5508, CEM5530
Some are also freely available from: