Fractaos is a 4-voice polyphonic, multitimbral fractal oscillator/synth voice for Eurorack. From a musical perspective, it is not just a sound source—it can be the core of an entire melodic layer, from mono leads to poly chords, tuned percussion, drones, and evolving harmonic textures.
Since only one manual was provided here, I’ll focus on how this module can be used in a system to create melodic material and how to patch around its strengths.
Fractaos is especially strong for:
Its sound engine is unusual: each of 4 voices contains a driver oscillator + follower oscillator, with fractal algorithms creating the waveform structure in real time. That means melodic parts can be much more animated than a typical subtractive oscillator, especially when using:
Use one voice as a lead by driving Fractaos from:
Choose more pitch-coherent geometric fractals such as:
These are likely to give the most stable harmonic behavior for melodic lines.
This gives you a lead that can move from: - clean and glassy - to vocal/formant-like - to unstable, metallic, or quasi-acoustic
That makes Fractaos great for melodies that need motion without extra modulation sources.
Fractaos supports 4-voice polyphony, so it can function like a complete poly synth voice in a rack.
You can play chords through: - MIDI polyphonic mode - 4 separate 1V/oct + trig inputs - a polyphonic sequencer or MIDI-to-CV setup
Each note has: - its own oscillator pair - its own ADSR envelope - its own resonant fractal filter
So chord voicings have internal separation and movement rather than sounding flat.
For stable harmonic content: - Keep Chaos moderate - Use geometric fractals - Use Spread subtly - Use Texture carefully for resonant color
For lush pads/chords: - Use Texture fractals as the main oscillator - Add a geometric primitive - Slow Speed - Medium Amount - Long ADSR attack/release
This is ideal for: - ambient harmony - synth-pop chord beds - cinematic sustained harmony - slow-moving generative tonal clusters
Fractaos should shine with: - gate sequencers - pitch sequencers - MIDI arp sources - generative CV
Because the sound source is internally animated, even simple note patterns can feel complex.
Feed: - pitch CV to one voice or several voices - synced triggers to the trig input(s)
Use: - Loop OFF / Trig ON for note-retriggered modulation - Speed to control modulation cycle - Amount to control how much the primitive shapes each note event
This makes every note articulate with a slightly different internal contour, which is very useful for: - plucky arps - pseudo-acoustic phrases - animated ostinatos
This is the main sound identity.
The manual suggests the 14 geometric fractals are the most spectrally defined and reproducible.
Especially melodic: - Fibonacci: warm, useful general-purpose tone - Koch: crystalline highs, brass-like lows - Julia: softer and smoother - Mandelbrot: bright and harmonically rich - Rössler: deformed-sine character - Sierpinski: odd harmonic brightness
These can be good for melodies when you want notes to feel unstable, percussive, or semi-atonal.
This is the secondary fractal used as modulation source.
For melodic clarity, use primitive shapes that: - complement the main fractal - don’t destabilize pitch too much - animate articulation rather than overwhelm it
A good practical approach: - choose a stable main fractal - choose a more animated primitive - then adjust Morph, Amount, and Speed
This creates melodic tones with movement while preserving note identity.
For melodic use, Morph is one of the most important controls.
It is not just a blend; the primitive still modulates the main fractal, so this affects both tone and behavior.
For melodies, the sweet spot is often low to mid Morph, where pitch remains clear but timbre is alive.
In normal mode, Spread detunes the follower relative to the driver.
For melodies: - low Spread = stable pitch center - medium Spread = animated doubling - high Spread = more dramatic harmonic shift
Because the follower can rise toward +1 octave, Spread can make simple melodies sound layered and “composed” rather than bare.
Texture acts like a fractal filter/resonance/formant extractor.
Use it to make lines feel: - vocal - resonant - organic - hollow - nasal - wind-instrument-like
Texture is very good for turning simple sequenced notes into musically expressive phrases without needing an external filter.
Chaos adds instability and can be quantized depending on fractal type.
For tonal music: - keep Chaos lower for basses, hooks, and chords - increase Chaos for transitional phrases, fills, and lead intensity
A very effective technique is to modulate Chaos slowly so a melody evolves over time while staying on the same pitch sequence.
Fractaos has an LFO/envelope behavior derived from the primitive and controlled by switches: - Loop - Trig - Morph(FM) - Spread - Chaos
This matters a lot musically, because you can make a melody behave differently depending on note articulation.
Set: - Loop OFF - Trig ON
Each note retriggers the primitive modulation contour. This is great for: - plucks - mallet-like synth lines - expressive phrases - repeatable note attacks
This behaves somewhat like a timbral envelope on every note.
Set: - Loop ON
Good for: - pads - sustained harmony - long melodies - legato-style evolving parts
Set: - Loop OFF - Trig OFF - Morph ON - Spread OFF - Chaos OFF
Now Amount becomes bipolar around center: - below center: internal feedback - center: neutral - above center: primitive modulates frequency of main fractal
Important note from the manual: - FM does not work when the main fractal is a Texture - FM has no effect on Drum curves
So for melodic FM sounds, stick to the geometric fractals.
One of the most interesting parts of Fractaos is that its Drum fractals are pitched and real-time synthesized, not samples.
Available drum models: - Kick - Tom - Snare - HiHat - Cymbal
The manual explicitly says MIDI pitch still affects them: - Kick and Tom behave fairly tonally - Snare, HiHat, Cymbal shift more in color/resonance than strict pitch
This means Fractaos can do: - tuned tom melodies - pitched kick-bass lines - hybrid percussive arps - melodic strikes layered with tonal tails
Because Morph can blend a Drum curve with a geometric primitive: - you can create a note that starts as percussion - then blooms into a pitched harmonic body
That is extremely useful for: - marimba-like lines - synthetic kalimba - tuned techno percussion - melodic IDM hits
This is one of the most distinctive melodic capabilities in the module.
Drone mode turns Fractaos into a continuously sounding 8-oscillator harmonic instrument.
In this mode: - oscillators no longer act as simple voice pairs - all 8 oscillators run simultaneously - Spread has a special chord/microtuning behavior
Even though it’s called “Drone,” it’s really also a harmonic composition mode.
These include: - major triad spread - minor triad spread - sus4/fifths - major 7th - minor 7th - add9 - add11 - add13 - just intonation - 7-limit flavor - 19-TET slice - Bohlen-Pierce subset
Drone mode can be used for: - harmonic pedal tones - chord drones under a sequence - evolving intros/outros - ambient tonal centers - modal beds for improvisation
Use the 1V/oct inputs or MIDI notes to transpose the individual voice pairs while in Drone mode. That means you can: - hold a fractal chord cluster - then move parts of it melodically - or transpose the whole harmonic field
This lets Fractaos behave like a moving chord machine.
MULTI mode is where Fractaos becomes especially compositional.
You can assign: - a different preset to each of the 4 voices - or leave some voices in LIVE mode
Each voice can respond to its own MIDI channel.
Example assignment: - Voice 1: bass preset - Voice 2: chord stab preset - Voice 3: lead preset - Voice 4: tuned tom/snare hit preset
Now one Fractaos becomes a mini ensemble.
Use separate MIDI channels or CV control to play: - one slow sustained line - one faster arpeggio - one chord voice - one accent voice
Because each voice can have a different preset, timbral separation is built in.
Use LIVE on one voice for hands-on tweaking while the other voices play stable preset-based roles.
This is very useful in performance: - one fixed harmonic bed - one improvisable lead voice
In MULTI mode: - outside Drone mode, preset voices keep their saved Spread - the panel Spread knob only affects LIVE voices
So for arrangement: - save precise spreads in presets for stable parts - use LIVE voices for manual expression
In Drone mode: - global Spread takes control of all 8 oscillators, including preset voices
That means an entire multitimbral setup can be swept into chordal motion together.
Fractaos includes one ADSR per voice, with shared settings across voices.
Parameters: - Attack: 1 ms to 8 s - Decay: up to 8 s - Sustain - Release: up to 12 s - Curve: linear, exponential, logarithmic
Good for: - plucks - sequences - bass lines - arpeggios
Good for: - pads - chord swells - ambient melodic overlays
Interesting note from the manual: Release still matters even with Sustain at 0.
This is useful for: - struck notes - pseudo-percussion - expressive decay tails - melodic phrases where early note release changes the articulation
That makes Fractaos good for dynamic phrase shaping, especially from a MIDI keyboard.
Fractaos has: - 8 CV inputs with attenuators for major parameters - 4 x 1V/oct inputs - 4 x trig inputs - MIDI input
Send: - pitch to one or more 1V/oct inputs - gates/trigs to matching trig inputs
Then use Fractaos internally for timbral motion.
Since Fractaos already has internal movement, external modulation works best for slow macro changes: - slowly scan Texture - gently modulate Morph - animate Pitch for vibrato/gliss - sweep Spread for widening
Because melodic use depends on pitch coherence, accurate 1V/oct sources will matter if using CV rather than MIDI.
Useful helpers in a system: - quantizer - sequential switch - clock divider - logic - performance mixer - stereo effects
Fractaos already outputs stereo, so it pairs especially well with: - reverb - delay - stereo chorus - spectral processors
These can elevate melodic parts from “synth voice” to “full arrangement layer.”
Result: lush evolving polyphonic harmonic bed.
Result: tuned metallic melody, great for IDM/electro/experimental techno.
Result: tuned percussion line that reads as both rhythm and melody.
Result: one module handling multiple melodic roles in a track.
Result: harmonic drone that still produces melodic motion through transposition of partial groups.
Fractaos can cover several melodic roles:
Use: - Fibonacci - Rössler - Julia - Kick/Tom hybrid patches
Keep: - low Chaos - moderate Morph - controlled Texture
Use: - Mandelbrot - Koch - Dragon - Sierpinski - FM mode
Great for: - solo melodies - hooks - expressive improvisation
Use: - geometric fractals for harmonic clarity - texture fractals for atmosphere - long ADSR - low/moderate Spread
Use: - trig-retriggered primitive behavior - short envelopes - moderate Amount - rhythmic sequencer input
Use: - Drum fractals + Morph toward geometric primitive - short to medium envelopes - sequenced pitch and rhythm
Because presets save: - knob values - switch states - envelope parameters
You can prepare: - verse pad - chorus lead - bridge percussion melody - outro drone
Preset voices can stay fixed while LIVE voices are tweaked manually.
The manual notes: - MIDI velocity can be enabled/disabled - aftertouch affects internal movement/timbral variation
That makes Fractaos especially playable as a melodic instrument from a keyboard.
Fractaos is best understood as a polyphonic fractal synthesizer voice with unusually rich internal animation. For melody creation, its strengths are:
If your goal is to create melodic components rather than just sound design experiments, Fractaos is strongest when used in these ways:
If you want, I can also turn this into: - a “best melodic patches for Fractaos” cheat sheet - a quick-start guide - or a genre-specific patch list for ambient, techno, IDM, or cinematic music.