Overview
A saturation and distortion engine firmware for the Qu-Bit Aurora module. Featuring 36 distinct algorithms organized across 6 banks, configurable in 3 distinct modes. Heavily inspired by the legendary Ohmforce Ohmicide.
Signal Path
flowchart LR
subgraph Input
IN[Input L/R]
end
subgraph Crossover
XO[Crossover
Mix knob] end subgraph LowPath[Low Frequency Path] LOW[Low Band
Dry] end subgraph DistortionChain[Distortion Chain] HIGH[High Band] PRE[Pre-HPF
Time knob
20Hz-2kHz] DIST[Mode + Algorithm
Warp / Blur / Reflect] BAL[Balance
RMS Matching] COMP[Compressor
Peak Control] DC[DC Block] CAB[Cab Sim
Optional] POST[Post-LPF 4th Order
Atmosphere knob
20Hz-20kHz] end subgraph Output MIX((+)) CLIP[Soft Clip] TRIM[Output Trim
Shift+Mix] GATE[Noise Gate] OUT[Output L/R] end IN --> XO XO --> LOW XO --> HIGH LOW --> MIX HIGH --> PRE --> DIST DIST -.->|Reference| BAL PRE -.->|Input RMS| BAL DIST --> BAL --> COMP --> DC --> CAB --> POST --> MIX MIX --> CLIP --> TRIM --> GATE --> OUT
Mix knob] end subgraph LowPath[Low Frequency Path] LOW[Low Band
Dry] end subgraph DistortionChain[Distortion Chain] HIGH[High Band] PRE[Pre-HPF
Time knob
20Hz-2kHz] DIST[Mode + Algorithm
Warp / Blur / Reflect] BAL[Balance
RMS Matching] COMP[Compressor
Peak Control] DC[DC Block] CAB[Cab Sim
Optional] POST[Post-LPF 4th Order
Atmosphere knob
20Hz-20kHz] end subgraph Output MIX((+)) CLIP[Soft Clip] TRIM[Output Trim
Shift+Mix] GATE[Noise Gate] OUT[Output L/R] end IN --> XO XO --> LOW XO --> HIGH LOW --> MIX HIGH --> PRE --> DIST DIST -.->|Reference| BAL PRE -.->|Input RMS| BAL DIST --> BAL --> COMP --> DC --> CAB --> POST --> MIX MIX --> CLIP --> TRIM --> GATE --> OUT
Signal Flow Details
- loginInput: Stereo audio input
- call_splitCrossover (Mix knob, 20-500Hz): Splits signal into low and high frequency bands. Low frequencies pass through dry (preserves bass punch), high frequencies go through distortion chain.
- filter_altPre-Filter (Time knob, 20Hz-2kHz): High-pass filter before distortion
- blur_circularMode + Algorithm: Distortion processing with selected algorithm and FAM mode
- balanceBalance: RMS-based level matching - matches distorted output to input loudness
- compressCompressor: Gentle peak control (threshold -3dB, ratio 8:1, attack 5ms, release 50ms)
- align_horizontal_centerDC Block: Removes DC offset from asymmetric distortion before cab sim
- speakerCab Sim (optional): V30 4x12 cabinet emulation (Resonant thump at 80Hz, phase smear 0.4ms delay)
- filter_altPost-Filter (Atmosphere knob, 20Hz-20kHz): 4th-order low-pass for tone shaping
- call_mergeCombine: Dry low frequencies + processed high frequencies
- content_cutSoft Clip: Safety limiter to prevent digital clipping
- volume_downOutput Trim (Shift+Mix, 0-2x): Final volume control after all processing
- lens_blurNoise Gate: Removes noise floor (threshold scales with drive)
Controls & CV Inputs
All CV inputs are bipolar (-5V to +5V, normalized to -1 to +1) and add directly to the corresponding knob value. The combined value is clamped before applying any scaling or mapping.
| Knob | CV Input | Function |
|---|---|---|
| Warp | CV_WARP | Drive/gain (1x to 100x, 0 to +40dB log). Use with envelope for dynamic distortion. |
| Blur | CV_BLUR | Algorithm-specific modulation. Use with LFO for animated textures. |
| Reflect | CV_REFLECT | BIAS parameter. Adds to BIAS after dead-center detection. Use for asymmetry modulation. |
| Atmosphere | CV_ATMOSPHERE | Post-filter cutoff (20Hz to 20kHz). Use for filter sweeps. |
| Time | CV_TIME | Pre-filter cutoff (20Hz to 2kHz). Use for dynamic bass control. |
| Mix | CV_MIX | Crossover frequency (20Hz to 500Hz). (Normal mode only) |
| Shift+Mix | — | Output trim (0x to 2x, default 60%) |
Banks & Modes
Bank Colors
Analog
Saturation & soft clipping
Fold
Wavefolding & complex shaping
Geometric
Variable geometric shaping
LoFi
Digital degradation
Chaos
Noise & physics
Temporal
Time-based & experimental
Modes (LED_FREEZE)
| Mode | Color | Description |
|---|---|---|
| S - Standard | Green | Raw distortion algorithm. The BIAS parameter adds a DC offset before the distortion is applied. The DC offset is removed after processing. |
| X - Tube | Orange | Simulates a tube amplifier (Rectifier sag, Crossover distortion, Triode vs Pentode shaping, Grid blocking, Harmonic blend). |
| O - Odd | Purple | Creates inharmonic distortion through envelope-based amplitude modulation (Inharmonic). Positive BIAS expands, Negative compresses harmonic spacing. |
Buttons & Gate Inputs
| Reverse | Next algorithm in bank |
| Freeze | Previous algorithm in bank |
| Shift + Reverse | Next bank |
| Shift + Freeze | Cycle Mode (S → X → O) |
| Hold Freeze 5s | Toggle V30 Cab Sim (LEDs blink 3x to confirm) |
| Gate | Function |
|---|---|
| GATE_FREEZE | Algorithm Hold - freezes input sample through distortion for buzzing sustain |
| GATE_REVERSE | Octave Up - full-wave rectification doubles fundamental frequency |
Ready to unleash the Tempest?
Download the latest firmware binary or build it yourself.
Download Tempest.bin from the repo releases, or run make at Firmware/Tempest to build it, then flash to Aurora via USB.