Morph a patch while it plays
Patch morphing usually means committing: press the button, lose the sound you had, hope the new one is better. Parasite's mutator does not commit. It runs the same engine as the randomizer, but instead of replacing the patch it blends toward the roll by an amount you set, and it does not interrupt what is sounding. Turn it a little for a sibling of the current patch. Turn it more for a cousin.
One engine with two verbs
Mutate runs the exact same draw pass as a roll: the same archetypes, the same measured priors, the same recipes. Then it blends that draw against a snapshot of the current patch. Randomize commits the draw. Mutate negotiates with it. The target it leans toward is always a patch the randomizer would have been willing to commit, structural rules included, so even a heavy mutation cannot drag you toward an inaudible filter or a dangling modulation. Everything the randomizer knows about what makes a patch coherent applies here too, which is why a mutation lands somewhere musical instead of somewhere random.
Two kinds of parameters and two blends
Continuous parameters interpolate in normalised space: cutoff drifts, envelopes stretch, amounts lean toward the drawn value. Each one lands as a single clean change, not a sweep, so the host sees what you did rather than a smear.
Discrete parameters, the choices and the toggles, are never interpolated, because half of a waveform choice is not a waveform. Instead, each one flips to the drawn value with a probability equal to the amount. At a low amount most choices survive; at a high amount most of them flip. The blend stays honest either way: every intermediate state is a patch the synth could actually hold.
Things that travel together
Some parameters only make sense as a pair, so they flip as one. A wave and its harmonic table travel as one unit under a single gate: you never get the new wave with the old spectrum. An LFO wave and its curve travel the same way. A custom table or curve that survives the gate bends rather than being replaced, so a spectrum you liked is still recognisable after the turn.
What the draw leaves alone drifts rather than resetting. Mutate perturbs; it does not destroy.
The amount is the whole interface
At zero, nothing happens. At one, it is a full roll. Between the two, you choose how far from home the patch travels. There is no second page of settings to learn: the knob is the feature.
The same ten section locks as the randomizer apply, honoured exactly the same way: Mod1, Mod2, Carrier, Macros, LFO, Filter, Pitch Env, Effects, Shaper, Global. Lock the filter you trust and mutate the operators around it.
It does not cut the sound
Mutate deliberately does not silence held notes, so you can turn it while a chord is ringing and hear the patch bend under your fingers. That is safe because every parameter reaches the voice through a smoothing ramp; the engine was built to be modulated, and the mutator is just another hand on the controls. This is what separates it from a roll, which replaces the patch and cuts whatever was sounding.
Identity and undo
A mutation keeps the patch's name and identity, where a roll renames the result. A mutated patch is still your patch, just further from where it started.
One turn is one undo step, custom curves included. Push too far, undo, and you are back to the exact state before the turn, tables and all.
When you want a clean slate instead
When the current patch is not worth keeping, skip the blending: the randomizer commits a full draw, resets everything it does not use, and documents exactly which measurements it rolls from.
The demo is the full plug-in. Download Parasite and turn the knob on a chord.