Cerberus – The Guardian at the Gates of Tone

In the mythical realm of audio, where pure sine waves flow like rivers and harmonics dance like spirits in the air, there stands a fearsome guardian at the boundary between the clean and the corrupted: Cerberus, the three-headed hound of distortion.

Legend says that Cerberus was forged in the underworld of analog circuitry, where vacuum tubes glow like embers and transformers hum their ancient songs. Unlike his mythological namesake who guards the gates of Hades, this Cerberus guards the threshold between pristine signal and beautiful destruction.

Each of his three heads possesses a unique power:
The First Head — the wise one — speaks in the language of filters, deciding what frequencies may pass into the realm of saturation. With slopes of 12, 24, or even 48 decibels, it shapes the incoming sound, preparing it for the trials ahead.

The Second Head — the fierce one — commands the four chains of saturation. Like chambers in the underworld, each chain can hold a different form of sonic destruction: the smooth warmth of Tube, the aggressive bite of Hard Clip, the folding madness of Foldback, or the vintage character of Tape. This head chooses which trials the audio must endure, stacking them in series like the circles of Dante’s inferno.

The Third Head — the serpent-tongued one — weaves modulation through the processing chains. With four LFOs at its command plus one global serpent coiling through all, it breathes life and motion into the static distortion, making the effect writhe and pulse like a living creature.
Together, the three heads work in terrifying harmony. Your sound enters pure and innocent — just a simple waveform seeking passage through the sonic realm. But Cerberus does not let anything pass unchanged.

“Your sound will not escape unscathed,” growls the beast as the gates open.

The audio trembles as it passes through the input filters, then faces the gauntlet of the four-slot chain where up to 16 different forms of saturation await. Each slot can crush, fold, clip, or warmly compress the signal. The processed sound then emerges through output filters, facing a final limiter before the panner and volume grant it freedom.

But here’s the secret: those who learn to tame Cerberus — who understand his parameters and know how to feed each head just the right amount of drive, gain, and modulation — discover that the beast is not truly their enemy. He is a craftsman of character, a sculptor of harmonics, turning lifeless digital signals into warm, breathing, analog-like creatures of sound.

And so musicians approach the gates, not with fear, but with anticipation, knowing that Cerberus will transform their pure tones into something richer, more complex, more alive.

Just don’t forget to feed him the right messages, or he might bite harder than you expect.

Multi-Algorithm Saturation & Distortion Processor

Cerberus is a comprehensive stereo saturation and distortion effect for Pure Data, offering 16 different saturation algorithms arranged in a flexible 4-slot processing chain.

Features

16 Saturation Algorithms: Soft (tanh), Hard Clip, Foldback, Tube, Tape, Bitcrush, Transformer, Vintage, Arctangent, Exponential, Hyperbolic, Polynomial, Rational, Sigmoid, and Diode

4-Slot Processing Chain: Combine up to 4 saturation algorithms in series with independent drive, gain, and wet controls per slot

Input (wet)/Output (global) Filtering: Configurable highpass and lowpass filters (12dB, 24dB, or 48dB slopes) before and after saturation processing

Output Filter: Korgon lowpass filter with resonance control

Noise Generator: Multiple noise types (White, Pink, Brown, Velvet variants) with envelope follower modulation

LFO System: 4 independent LFOs plus 1 global LFO, each with multiple waveforms, frequency modulation, and assignable modulation targets

Signal Chain: Gate → Input Filters → Saturation Chain → Wet/Dry Mix → Output Filters → Limiter → Panner → Volume
Limiter & Dynamics: Built-in gate and limiter for controlled output

Controls:

The bottom row of buttons accesses the individual settings.
– 1st C – F: Chain slots
– 1st C#: Ringmod
– 1st G – 2nd C: Chain slot LFOs
– 2nd D: Global LFO
– 2nd E: Wet input/output filters
– 2nd F: Noise/envelope follower
– 2nd G: Input gate
– 2nd A: Global (Mix, Input, Input level)
– 2nd B: Presets

The parameters in the first row are controlled with the encoder. If a second parameter is in the row, it is controlled with the encoder in combination with the AUX button.

The parameters in rows 2 – 5 are controlled with the potentiometers. If a second parameter is in the row, it is controlled with the same poti in combination with the AUX button.

LFO frequencies can be tapped with AUX.

To exit the patch, the encoder must be held down for more than one second.

Hold AUX for at least 3 seconds to reset the patch.

A Quick Guide (PDF) is also included in the patch directory and here: https://codeberg.org/attackallmonsters/audiokern/src/branch/cerberos/src/cerberos/quickguide.pdf

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New in version 1.0:
– Added ring mod (pre wet, press 1st C#)
– New algo Chebyshev

The ring modulator has two frequencies. The second frequency is relative to the primary frequency. The primary frequency can also be set using AUX and the Organelle or other MIDI keyboards/devices. The octave can be adjusted in the settings (2nd A). In “Classic” mode, only the primary frequency is used. All other modes also use the secondary frequency. “Independent” is interesting because the primary frequency is routed to the left channel and the secondary frequency to the right channel. A nice little stereo effect.

Chebyshev is more suitable for pure sine waves. A sine generator will be added in a later version. I don’t have enough time right now.
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A few things aren’t working quite right yet. Some of the parameter defaults are also not optimal. But it’s already working pretty well. More algorithms will probably follow. I’ll probably also add a polyphonic sine generator, because it can generate some pretty cool sounds using different chain algorithms. Otherwise, you can just attach a synthesizer or guitar. That works fine, too.

And if the sound is a bit too weak, more drive or input gain (2nd A) is the solution.

Let me know if something doesn’t work!

Image AI generated.

Have fun with the hellhound.

Version 0.2
Fix: The same algorithm could be assigned to multiple channels. If an algorithm is selected that is already active on another channel, it will be ignored.