Randomizer: Random Patch Generator

Most random buttons treat every knob as a coin toss. The result is noise: a closed filter over a silent oscillator, a release that never ends, four parameters fighting each other. Parasite is an FM synth with a randomizer that works the other way around. It is a random patch generator whose distributions were measured from the factory bank, so what it rolls already behaves like an instrument.

An archetype comes first

Every roll starts by drawing an archetype, weighted toward the short and the percussive because that is what the bank is made of. The archetype pins the envelope and the tail character before any other parameter is chosen. A pluck decays like a pluck, a pad breathes like a pad, and nothing drawn afterwards can undo that. It is the difference between a patch and a pile of settings.

Priors instead of coin tosses

The distributions behind each parameter are measured from the factory bank, and they are drawn in normalised knob space, so each parameter keeps its own skew. Some of what the corpus shows:

Filter cutoff is bimodal. Real patches sit low or open, rarely in the mushy middle.
Resonance and cutoff move against each other. A low cutoff tends to bring a resonant peak with it.
Fine tune is quantised to musical intervals instead of landing anywhere in between.
Many amount knobs sit at zero far more often than a flat random would put them, because that is where sound designers leave them.

Recipes on top

Single knobs drawn well still do not make a sound design decision, so on top of the priors sit coherent recipes, each moving a whole group of parameters together the way a person would rather than one knob at a time. One of them parks an operator at a sub audio rate inside the FM graph, which is a place nothing outside the engine can reach.

No roll arrives silent

A patch that arrives inaudible is a wasted roll, so the generator refuses to produce one. Draw a filter low enough to mute the sound and it has to earn it: either something moves that filter, or the draw is replaced. You never press the button and get silence.

It draws its own material

The roll is not limited to the stock waveforms. Some rolls generate a custom harmonic spectrum for an oscillator, or draw an LFO curve that is not one of the presets. Two rolls of the same archetype can still differ at the level of raw timbre, not just settings.

No leftovers

Anything a roll does not engage is reset to its default. Every effect and every texture is drawn fresh or reset on each roll, and an LFO curve always matches the wave it was drawn with. Nothing bleeds from the previous patch into the next one, so a roll never inherits a forgotten effect send or a stray modulation from three rolls ago. The only way state carries across rolls is a lock, and a lock is a decision you made.

Every roll is also one undo step, custom curves included. A bad roll costs one undo, nothing more.

Locks

Ten sections can be locked, matching the panels of the advanced page: Mod1, Mod2, Carrier, Macros, LFO, Filter, Pitch Env, Effects, Shaper, Global. Lock the filter you like and reroll everything around it. Lock everything but the effects and use the roll as an effects dice.

A lock suppresses the writes, never the draws, so the sequence of rolls stays reproducible whatever you lock or unlock along the way. The FM algorithm itself is only rewritten when all three operator panels are unlocked, because rewiring the graph under a locked operator would change the sound the lock was protecting.

When you need it not to commit

Randomize replaces the patch, so it silences held notes. When you want the same engine without the interruption, the mutator runs the identical draw and blends it into what is already sounding, by an amount you set.

The demo is the full plug-in. Download Parasite and roll.