Plasma Synthesiser

Electronic Musical Instrument

The Plasma Synthesiser

In its initial incarnation, Plasma was a two-voice Virtual Analogue monophonic synthesiser with an integrated sequencer. Later incarnations added CEM-based analogue filters and envelope generators although this was at a time when Curtis chips were in very short supply so adding these components was not deemed a sensible long term strategy.

Initially, the oscillators were the instrument's weakest link. Aliasing was a serious problem. Later experiments with Karplus-Strong and PolyBLEP oscillators helped to improve the sound but the correct solution - band limited oscillators - were still a way off.

Current Status:

  • Last updated : 02-Feb-23
  • Two voice architecture with digital filter and EG's working
  • Hardware checks out and working as it should
  • Midi-In fast and responsive. Pitch bend not working. Modulation wheel only partially working.
  • Envelope generators imprecise
  • Effects - delay working, reverb sounds crude and metallic
  • Sequencer - single channel record and playback working

Next steps:

  • 1. Figure out how to develop the front panel controls so that they match up with the capabilities of the Teensy audio library
  • 2. Design the new audio path using the Teensy audio tool
  • 3. Port Teensy Midi-over-USB protocol
  • 4. Design a new CPU card around a Teensy 3.5
  • 5. Solve the LCD mounting issue
  • 6. Design an enclosure for the rack-mounting version
  • 7. Don't forget to add a volume knob on the output (ahem...)


Contact Unreal Devices

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The office is closed Saturday and Sunday, and all major holidays.