These instruments are no longer in production, but they remain an important part of our story.
The Demon Core Oscillator, Demon Core Expander, and Neutron Flux Filter represent early explorations of our approach to sound — driven by a desire to push beyond the expected and reimagine what these instruments could be.
With these modules, we set out to explore new architectures and sonic possibilities, combining analog foundations with unconventional control to create something distinct. Out of this exploration emerged the sound that became characteristic of Supercritical: rich DCO-based tones shaped by character, warmth, and saturation.
Each module helped shape the direction of what Supercritical Synthesizers is today.
While these products have been discontinued, their spirit lives on.
The Demon Core Oscillator is built around our MDCO (Multiperiod Digitally Controlled Oscillator), a unique design where a single analog core generates multiple simultaneous waves with independent pitch and phase control — effectively delivering up to 16 analog voices.
These voices can be tightly tuned, statically detuned, or set to drift, allowing sounds that range from precise digital textures to unstable vintage-style character. At balanced settings, the result recalls the warmth of classic 80s VCO designs.
Based on saw and pulse waves (with PWM), more complex timbres can be created through unison stacking and phase sync. Slight detuning introduces rich harmonics, while sync triggering can produce dynamic, flanging-like effects — especially effective for dense bass sounds.
Voices can be arranged in unison and octave stacks across up to six octaves, with accurate A440 tuning and high-precision 1V/Oct tracking. Linear FM and fine control ensure both musicality and flexibility.
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.
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.
The Demon Core Expander extends the capabilities of the host oscillator into a fully playable polyphonic instrument. Its core feature is flexible polyphony: all 16 voices can be arranged in a wide range of configurations, from dense unison stacks to expressive multi-voice setups, with support for octave layering.
Polyphony can be controlled via four 1V/Oct CV inputs or MIDI. CV inputs handle the first voices, while MIDI unlocks full polyphonic control and introduces per-voice gating. Although the oscillator itself runs continuously, the expander enables “virtual VCAs” for each voice — all implemented in the analog domain.
Per-voice gating is paired with integrated ADSR envelopes, transforming the oscillator into a powerful pad and string machine. A dedicated gate output, driven by MIDI, allows further interaction with external modules and supports retriggering for more dynamic performance.
MIDI connectivity is handled via 3.5 mm TRS with automatic Type A/B detection, along with a configurable MIDI thru for flexible routing.
Additional controls expand the phase sync behavior, allowing precise shaping of timing from tight, punchy bass to long evolving textures. Extended CV modes provide further control over sync timing and variation, octave stacking depth, and modulation via an internal LFO.
As an expander module, it requires the Demon Core Oscillator to operate.
The Neutron Flux Filter is a stereo analog filter with digital control, designed to move seamlessly between classic character and entirely new sonic territory. Its dual 4-pole cores can operate in stereo, split configurations, or be chained into a steep 8-pole mono filter.
A range of selectable “characters” defines the filter’s behavior, from warm and rounded to sharp, resonant, or unstable. These models capture the spirit of classic designs while extending them into more experimental territory, with additional characters and updates expanding the palette further.
An integrated overdrive stage adds up to +20 dB of gain before the filter core, allowing anything from subtle saturation to aggressive distortion. The flexible topology enables independent drive behavior across the cores, opening up more complex signal paths.
Stereo operation goes beyond simple widening by introducing controlled cutoff spread and drift between channels. This creates a dynamic, animated stereo image — more akin to a moving spectral space than traditional chorus or delay effects.
With its combination of analog signal path and flexible digital control, Neutron Flux offers a wide spectrum of filtering, from familiar tones to highly expressive and unconventional textures.
You can update your Neutron Flux Filter’s firmware by holding BUTTON and POLES buttons and turning the power on. The module then enters bootloader state. Next, two different patterns are shown on the LED ring around CHARACTER. The second shows the version number (displayed below with each version). Don’t mind the first 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 CHARACTER 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 red 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.
When the module is waiting for the update files, the yellow LEDs show the input level. Try to run the audio via a VCA or an amplifier module if the level is not sufficient. The update may require multiple attempts. Check that the file has completely downloaded.
