Years ago, in the Elektor magazine, an article appeared on the (then) new Curtis Synthesizer IC’s (CEM). Many synths were build around these specialised IC’s until analog synths went out of interest late 80’s. The Elektor magazine proposed applications for these chips in a Polyphonic synthesizer.

Now that DIY building a synthesizer and an analog revival is taking place many of us were looking for these CEM chips, which were not produced any longer. But since a couple of years the original Curtis chips are manufactured again (yet not all different chips available) and an alternative is available as the Alfa series AS chips.

Soon we will feature a more extended post about these chips, including the legendary SSM series.

Curtis does have a facebook group. The Alfa RPAR chips are manufactured in Riga, visit their website.

This is a list of the CEM chips available at some time:

  • CEM3310 ENV ADSR
  • CEM3312 ADSR + VCA
  • CEM3318 ADSR (microprocessor-controlled via two voltages)
  • CEM3320 24 dB/Oct. VC multimode filter
  • CEM3328 24 dB/Oct. VC LPF
  • CEM3330 exp/lin VCA
  • CEM3335 exp VCA
  • CEM3340 VCO (Saw,Tri,Pulse)
  • CEM3345 VCO (Saw,Tri,Pulse) with comparator
  • CEM3350 12 dB/oct Multimode Filter x2 (no notch)
  • CEM3360 VCA x2
  • CEM3365 DAC
  • CEM3371 Envelope x2
  • CEM3372 24 dB/oct. Filter, Mix, VCA
  • CEM3374 VCO x2 (PWMable Pulse, Tri, Saw)
  • CEM3378 24 dB/oct. VCF, 2-channel mixer, VCA
  • CEM3379 24 dB/oct. VCF, VCA, VC pan
  • CEM3381 / PDA381 VCA x2 linear
  • CEM3382 / PDA382 VCA x2 log
  • CEM3385 24 dB/oct Filter (LoFi)
  • CEM3387 signal processor 3-4 pole cascade Filter, VC Pan/VCA
  • CEM3389 signal processor 4 pole Filter, VC resonance, VCA, VC Pan
  • CEM3391 Microprocessor Controllable: VCF, VCA, Env (ADSR)
  • CEM3394 Microprocessor Controllable: VCO, VCF, VCA, external input (complete synth voice)
  • CEM3396 Microprocessor Controllable: Wave-Shaper x2, VCF, VCA
  • CEM3397 same core design as CEM3396 but with separate external signal (noise/sub/wavetable) input and VCA to mix stage and additional
  • CEM5508 / PD508 Octal Sample&Hold (8x)
  • CEM5530 30ch multiplex sample&hold (Prophet VS)