16 Voice Demon Core Oscillator

The catch of our Demon Core Oscillator is in a new innovation called the MDCO (Multiperiod Digitally Controlled Oscillator) which allows a single analog oscillator core to form multiple simultaneous waves with pitch and phase control. In practice this means 16 analog voices which can be controlled separately.

The sonic gravy is found in the fine tuning of the voices. They can be set in strict digital tuning, be statically detuned (spread) or set to drift (Core Stability). Or both. The spread control takes us from a brutalist digital cityscape to super saw planet while the core stability ranges from vintage DCO synthesizers to a broken and misbehaving vintage VCO. On the middle ground of both controls the sound resembles that of the old warm VCO designs of the 80’s (which we are very fond of).

The basic building blocks are saw and pulse waves (with PWM) but more complex waveforms can be created using two or more unison waves and triggering the phase sync via the sync trigger input. Simultaneous unison waves in the same phase increase the amplitude but when slightly detuned they generate strange harmonics and form unusual waveforms. If more voices are used, spread is opened slightly and the sync trigger input is used with gate signal, the phase sync acts like a decay envelope producing flanging effect. This can be used for massive bass synthesizer sounds.

All of the voices can be configured in different depths of unison and octave stack. Up to 6 octaves are supported. The 16 voices are spread evenly between the octaves.

Since we know the precise tuning of the waves the master tuning can be accurately set in A440 across 6 octaves via a tuning LED. This makes the module handy for practical applications requiring accurate pitch. The 1V/Oct pitch control is calibrated to high precision. A bipolar linear FM with a attenuator controls the master pitch in conjunction with the 1V/oct input.

While the Demon Core Oscillator stores megatons of energy in itself, it can be boosted to maximum yield by attaching the Demon Core Expander to it. Check it out over here.

Tech specs:

  • 12hp, skiff friendly with 25mm depth.
  • 120mA +12V and 20mA -12V
  • 16 configurable voices (octave, stacks)
  • Saw and pulse waves with PWM ranging from 0-100%
  • Coarse tune for 6 octave range with half-step increments
  • Fine tune for ± half step range
  • A blinking tuning indicator for finding C note in every octave and A440 fine tuning
  • 1V/oct master pitch CV
  • Linear FM CV (±5V) with attenuator
  • Combined Spread / PWM CV (±8V) with offset function
  • Stability CV (±8V) with offset function
  • Trigger input for synchronizing the phases for all waves
  • Mono audio output
  • A function (shift) button to do magic for different controls!
  • Software updates via audio
  • Secure shrouded power connector with a supplied power cable

Firmware updates


You can update your Demon Core Oscillator’s firmware by holding WAVE, FUNCTION and VOICES buttons and turning the power on. The module then enters bootloader state. Next, two different patterns are shown on the 16 LED ring. The first shows the version number (displayed below with each version). Don’t mind the second pattern, it is for our debugging purposes. After that the module is waiting for the firmware update. You can connect your computer or phone’s headphone output to FM CV jack and play the firmware audio file. The progress is shown on the voices LED array. After updating the firmware the module enters play mode.

From an ordinary headphone output on a smartphone, volume should be turned way up to achieve proper result. If a animated pattern is shown, cycle power, go to the bootloader state and try again. WARNING: the audio files below contain 56k modem-esque DAMN LOUD audio. Don’t damage your ears or audio equipment with it.

The firmware update will reset the module and MIDI settings.


DCO Firmware 1.3

Bug fix:  MIDI channel was not restored from memory correctly (since v1.2)


DCO Firmware 1.2

Firmware 1.2 LED Pattern

  • Poly portamento: hold “Voices” and turn “FM Amount” on the main module to adjust rate
  • CV gate trigger: Hold “Function” and turn “FM Amount” on the Expander above 5% to turn on CV gate.
    Now a fast change, bigger than about 0.6 semitones, in the expander CV inputs triggers a note in the corresponding voice.
    The gate length is determined by position of “FM Amount” when holding “Function”.
    The generated gate is also output to the “Gate/Trig” output.


    • Going to stream mode always resets all MIDI notes.
      This makes it easier to start the stream mode at a known state.
    • Certain errors are now signaled by flashing all the module and/or expander LED’s 12 times on startup.

We do not expect these errors to be encountered in the wild.
However, if you do have flashing LED’s on startup, please contact us at info@supercriticalsynthesizers.com

Bug fixes:

    • when resetting the module to defaults (i.e. long hold of Wave + Function + Voices), the FM Amount on the module would be set to that of the expander.
    • main module FM amount, expander attack and decay were not restored from memory on power on, but were instead reset to their current physical positions.
    • in stream mode, it was possible for some of the voices to be left to a very low note (MIDI note -1) before any actual MIDI notes are played.

This would also affect the CV inputs, which control pitch relative to the currently chosen MIDI note (or the default, if none are played).


DCO Firmware 1.1

Firmware 1.1 LED Pattern

  • Virtual VCA zipper noise at medium release and attack times has been significantly reduced.

Bug fixes:

  • At 5 voices, stack depth 3, using the pulse waveform, the maximum frequency was limited to about 600Hz, above which the frequency would wrap down by an octave. This has been raised to 2.5kHz


DCO Firmware 1.0

Firmware 1.0 LED Pattern

  • Init release
  • Modules 1-100 have this firmware when shipped


Other useful info