Fractaos is unusually deep for a Eurorack oscillator because it’s not just “an oscillator with FM.” It’s really:
That means the best sounds usually come from stacking several small motions at once rather than one huge modulation source.
From the manual, the most modulation-friendly panel parameters are:
And the switches decide where the primitive-derived modulation goes:
These are not CV-modulatable: - Depth - Primitive Depth
So for live patching, treat Depth settings as your “static engine configuration,” then animate: - chaos - morph - texture - spread - speed/amount
That’s where the sound comes alive.
The primitive isn’t just a second oscillator. It also creates internal motion. The switches let you decide whether that motion affects: - morphing - spread/detune - chaos
This is one of the module’s strongest features.
Texture does a lot at once: - fractal filter resonance - formant extraction/detection - micro-detuning - filter intensity
So in practice: - low Texture = more direct oscillator identity - medium Texture = vocal/formant/organic complexity - high Texture = unstable, spectral, resonant, sometimes noisy behavior
That makes Spread one of the best performance parameters on the module.
Each fractal responds differently to Chaos. Some become unstable, some become richer, some just get slightly rougher. So the best approach is: - pick a fractal family for the musical role - then find its sweet-spot chaos window
Best starting points: - Rule30 — granular, dense, percussive - Collatz — stepped and jerky, rhythmic - Dragon — beating and expressive under chaos - Hénon — unstable/experimental - Lorenz — complex drifting, irregular - Drum models: Kick, Tom, Snare, HiHat, Cymbal
Also try morphing Drum curves with geometric primitives for hybrid percussion.
Best starting points: - Mandelbrot — bright, crystalline, harmonically rich - Cantor — gapped saw/pulse character - Sierpinski — strong odd harmonics - Dragon — moving/internal beating - Rule30 — nasty bass texture - Koch — brassy low register - Fibonacci — warmer foundation - Hilbert — stepped rectangular spectral behavior
Best starting points: - Cloud - Storm - String - Ensemble - Cluster - Lorenz - Rössler - Julia - Fibonacci
For pads, the texture fractals as the main fractal are especially important because they’re intentionally noisy/atmospheric.
This is one of the best “free complexity” moves.
Use: - a slow triangle LFO - random slewed voltage - very slow envelope - offset + attenuated modulation
Why it works: Texture changes not only filter intensity but also formants and micro-detuning, so even tiny movement sounds rich.
Use a fast-decay envelope into F-Chaos or P-Chaos.
Why: A burst of chaos at the attack makes sounds feel: - struck - ripped - unstable - snarling
This is excellent for: - distorted kicks - tearing bass attacks - noisy transient design
Result: clean-ish body with violent transient articulation.
Use: - Loop OFF - Trig ON
Now each new note retriggers the primitive contour from the beginning.
If Morph, Spread, or Chaos are enabled, each hit/note gets its own animated shape.
This is one of the best methods for: - punchy bass plucks - animated percussion - articulated sequences
Use: - Loop ON - optional Trig ON if you want note-synced restarts
Now the primitive becomes a looping LFO.
Great for: - wobble basses - fluttering spectral percussion - living drones - breathing pads
The manual’s “simplified FM mode” is huge for aggressive sounds.
Set: - Loop OFF - Trig OFF - Morph ON - Spread OFF - Chaos OFF
Now Amount becomes bipolar: - 0–50%: internal feedback - center: neutral - 50–100%: primitive 2 modulates main fractal frequency
This is your primary route to: - tearing reese-like basses - metallic attacks - snarling dubstep timbres - overdriven, deformed waveforms
FM does not work when the main fractal is a Texture fractal, and does not affect Drum curves.
Fractaos is unusually good at percussion because you can combine: - actual drum models - geometric fractals - primitive-triggered contouring - chaos bursts - texture resonance
Patch: - trigger mult -> Fractaos trig + external fast envelope - external envelope -> Texture CV - another envelope or accent CV -> F-Chaos CV
This gives: - attack-dependent filter/formant bite - aggressive transient dirt - more “broken speaker” energy
Try: - more Texture - more Morph - primitive = Cantor or Collatz - pitch lower - higher Chaos on accented hits
You get: - percussive shell/noise from Snare - digital tearing from primitive modulation - unstable noise sprays from chaos - flamming metallic edges via spread modulation
Sequence pitch slightly even on Snare. The manual says pitch shifts color/resonance/internal filtering strongly on Snare/HiHat/Cymbal. Tiny pitch sequences can create a whole kit from one patch.
Spread modulation on short metallic voices introduces oscillating detune and can create: - shaken hat texture - digital sizzle - unstable cymbal wash
Use random stepped CV with attenuation into: - P-Chaos - or Morph
Now every hit gets a slightly different color without losing the patch identity.
One of Fractaos’s coolest manual-noted features is using Morph with Drum curves to blend percussion with the second geometric fractal.
You can create: - percussive attack + pitched sustain - drum-to-bass hybrids - “hit becomes note” sounds - tuned tom stabs
This is excellent for modern bass music fills.
Fractaos can do bass very well if you focus less on “traditional analog FM bass” and more on: - morph movement - attack chaos - spread detune - texture/formants - simplified FM mode
This creates multiple interlocked movements: - spectral shape changing from Morph modulation - detune throbbing from Spread modulation - chaos-driven internal roughness - filter/formant animation from Texture
Patch an LFO or sequencer lane into: - Texture CV for vowel/growl emphasis - Morph CV for phrase evolution - Pitch CV for slides or stepped riffs
Clock a stepped random or sequenced CV into Texture while the internal primitive loops on Morph. That gives macro movement plus internal motion.
This gives you animated detune between driver/follower. It’s not a classic supersaw detune; it’s stranger and often gnarlier.
Then add: - a little Chaos ON - slow CV to Texture - envelope to F-Chaos
This keeps body and adds attack abrasion.
Fractaos will sound huge through: - wavefolder - distortion - lowpass or bandpass filter - VCA with envelope follower sidechaining
But even before external processing, Spread + Texture is already very “reese-adjacent.”
This is one of the most important bass modes on the module.
Use a sequencer with: - pitch CV into a voice - gate/trig into trig input - accent envelope into Texture - slower modulation into P-Chaos
This produces bass phrases with stable pitch but moving overtone violence.
Automate Amount itself with CV while in FM mode. Small CV moves near the center crossing point can dramatically change the spectral behavior.
This makes each note speak with an internal motion envelope rather than a static tone.
Use external envelope into Spread CV for pitch-tear on every hit.
Subtle version: - low attenuation - very fast decay
Extreme version: - moderate attenuation - medium decay
Result: a “rip” or “bark” at note onset.
Fractaos loves sequencer modulation lanes.
Use a sequencer row or CV track to step-modulate one of: - Texture - Morph - F-Chaos - P-Chaos - Amount
Best combination: - one stepped lane to Texture - one slewed/random lane to P-Chaos - internal primitive modulating Morph
That gives: - step-specific tone - overall living movement - controlled unpredictability
This is where Fractaos gets very special because of: - Texture fractals - Drone mode - 8-oscillator chord spread - slow primitive movement - formant and resonance behavior
Use Spread in its three zones:
Very slowly sweep Spread through the Drone chord region while also slowly modulating Texture.
This changes both: - tuning relationships - spectral identity
The result feels composed rather than merely filtered.
Texture plus slow Morph modulation creates formant/vocal drift without requiring an actual vocal filter.
Use tiny amounts. On Fractaos, subtle is often more eerie than extreme.
The manual notes Storm can evoke thunder/dense rain depending on Amount, Chaos, Depth, and Texture. Modulating Chaos and Texture slowly is the key.
This creates weather systems, not just pads.
The microtuning options especially will produce eerie, alien, haunted harmony.
Use a slow CV into Pitch while in Drone mode for whole-cloud transposition. If you have four pitch CV sources, you can offset the four voice pairs separately while the 8-oscillator spread remains global.
Fractaos rewards particular modulation types.
Use these on: - Chaos - Texture - Morph - Spread
Use these on: - Texture - Amount - Morph - Chaos
Use these on: - Texture - Morph - Pitch - Chaos very lightly
Best for: - plucks - kicks - snare hybrids - bass stabs
Best for: - dubstep movement - chorused bass - unstable drones
Best for: - drum transient corruption - bass attack tear - broken digital edge
Best for: - metallic basses - harsh stabs - distorted synth tones
Best for: - extreme sound design - horror drones - glitch percussion - mutant bass FX
Use attenuation and restraint here; it can get wild quickly.
Goal: aggressive moving bass
Wide, growling, moving bass with attack abrasion and phrase evolution.
Goal: distorted percussive hit with synthetic tail
Snare hit with tearing digital edge, unstable brightness, and a weird tonal residue.
Goal: eerie ambient drone
A drifting harmonic cloud with slightly uncanny tuning and spectral vocal-like motion.
If I had to choose a single performance knob on Fractaos for live interest, it would often be Texture. It can move the sound from: - defined - to resonant - to organic - to unstable without simply acting like a plain filter sweep.
Especially for percussion and bass, Chaos is often strongest when it is: - moderate at rest - pushed by envelope/accent CV on attack
That preserves body while adding violence.
Too much Morph can dissolve the core note. Start lower than you think, then add modulation. Bass usually hits harder when the center of gravity remains audible.
This is one of the module’s signature tricks: - drum transient - geometric sustain - fractured hybrid tone
Perfect for: - neuro percussion - cinematic impacts - weird tom/bass hits
On many modules, detune spread is just width. Here it becomes: - interval architecture - chord selection - microtonal atmosphere
That’s much more powerful than typical unison spread.
The most unique thing about Fractaos is that it doesn’t sound best when treated like a normal oscillator plus filter. It excels when you think in layers:
If you want, I can also turn this into: - a cheat sheet of best fractal pairings - a set of 20 patch recipes - or a “what to patch into each CV input” guide