Unusable Engineering ApS
synth

Partials & Discrepancies

An 8-voice additive polysynth with slot-based motion, up to 128 partials per voice, and semi-controlled divergence between voices.

Additive SynthAU/VST3Mac/Win

1.3.3 - 2026-09-05

Pitch LFO

  • Fixed a bug that broke the pitch LFO in mono mode.

1.3.2 - 2026-09-01

Live View

  • Added Live View for following active voices directly in the waveform editor.
  • The editor now displays the followed voice's slewed node geometry and partial settings in real time.
  • The slot ring follows the voice's current sequencer position.
  • Live View automatically moves to another active voice when the followed voice approaches the end of its release.
  • Editing nodes, partial controls, locks, randomization, copy, paste, or clear temporarily pauses Live View on the current slot.
  • Live View resumes automatically after editing (a few seconds delay).
  • Loading a preset now shows its first active slot instead of an inactive slot.

X-Voice FM

  • Added circular cross-voice linear FM, where each voice modulates the following voice and voice 8 feeds back into voice 1.
  • Added selectable FILT and OSC modulation sources.
  • FILT uses the previous voice's filtered pre-VCA signal for smoother modulation.
  • OSC uses its oscillator output directly and has a reduced range for easier control.
  • X-Voice FM is stored independently in every oscillator slot and slews with the slot sequencer.
  • Added a lock for keeping X-Voice FM fixed across all slots.
  • Included X-Voice FM in slot randomization, copy, paste, and Live View.

Velocity Position

  • Added VEL->POS option when the slot sequencer clock is off.
  • Note velocity can now set each voice's position around the active oscillator slots.
  • Preset Slew controls the interpolation between velocity-selected positions.
  • Velocity positioning works together with Voice Offset and Position Discrepancy.
  • When KBD->RST and KBD->NEXT are combined, velocity selects the starting position before the one-step movement.

Wave Editing

  • Added Shift+drag on nodes to restrict movement to either the horizontal or vertical axis.
  • Added Option/Alt+drag on a node to scale the complete waveform vertically around zero.
  • Scaling can pass through zero to invert the waveform.

Shortcuts And History

  • Added wave-slot copy and paste with Cmd/Ctrl+C and Cmd/Ctrl+V.
  • Added multi-step undo with Cmd/Ctrl+Z.
  • Added redo with Cmd/Ctrl+Shift+Z.

Interface Performance And Stability

  • Reduced duplicate parameter, transport, geometry, and DSP messages sent between the plugin and WebView.
  • Limited visual telemetry to the interface's actual 30 FPS update rate.
  • Added bridge backpressure so stale visual frames cannot accumulate when WebView rendering falls behind.
  • Reduced unnecessary React animation and spectrum work.
  • Improved pointer, wheel, focus, and keyboard-release handling to prevent interrupted gestures and short interface freezes.
Available Downloads

All Partially Dirty

20 presets exploring the dirtier and noisier areas of Partials & Discrepancies.

Type
Preset pack
Requires
Partials & Discrepancies 1.3.2+
Author
Rasmus
Download ZIP

What it is

Partials & Discrepancies is an 8-voice synth built around one additive oscillator per voice. It was made as a more disharmonic and experimental companion to Curves & Membranes, but still with a layout where you can actually follow what is happening and stay close to the sound while it shifts.

Each slot stores a full partial shape with seven node handles plus seven behavior parameters, so the sound can move between harmonic and more broken states. Offset, Wave Warp, and Weirdness push the partials away from neat spacing, while the slot sequencer, voice offset, and discrepancy controls let voices drift and diverge in very musical ways.

It can do animated pads, unstable leads, brittle static digital sounds, and inharmonic sweeps. The architecture is deliberately simple, with a compact set of controls that can move from sweet harmony to absolute mayhem and back again.

Highlights

128 partial additive core

Each voice is built from up to 128 realtime generated partials that can align or drift off the harmonic grid.

MTS-ESP and MPE

Partials & Discrepancies supports MTS-ESP for alternative tuning systems and works with MPE-compatible controllers for more expressive playing.

Slot sequencing

Up to eight slots store full partial states and can sweep, step, slew, or key-follow between one another.

Discrepancy controls

Each voice gets its own stable random character, so tuning, filter, stereo, and slot position can drift away by controlled amounts.

Cross-Voice FM

Let each voice modulate the next. As you play the effect changes with your notes, and slowly crushes the sound to dirt and pieces

Velocity -> Slot

Velocity decides which slot will be played, letting you build sounds that transforms with each key stroke.

Full walkthrough

A walkthrough of Partials & Discrepancies covering the additive partial model, slot-based motion, discrepancy controls, and how the synth stays fast to work with while moving into stranger territory.

A no-talking set of sound examples showing what Partials & Discrepancies can do across animated, harmonic, dissonant, and more unstable territory.

A little session showing what the Discrepancies controls do, and how they can be used to breathe life or a bit of chaos into patches.

An unplanned 26-minute session using the additive oscillator of Partials & Discrepancies in a few different ways. Good if you have time to kill, are looking for some boredom, or want to get to know the oscillator a bit better.

Reference

Quick user guide

The interface is divided into oscillator shaping, slot motion, modulation, filtering, envelopes, output, and per-voice discrepancy. This guide covers the operating modes and the shortcuts used while editing.

01

Signal and voice modes

Voice mode, oscillator register, and live voice controls

Each voice uses one additive oscillator with up to 128 partials. The oscillator passes through the voice filter and amplifier before reaching the output stage.

Poly / Dual / Unison select independent or stacked voice allocation.

32' / 16' / 8' / 4' select the oscillator register.

PB48 steps through pitch-bend ranges of 48, 12, 7, 5, 3, and 2 semitones.

Live View follows an active voice in the slot editor. Editing pauses the live view display temporarily.

02

Partial editor

Additive partial node editor and partial controls

The seven nodes define the amplitude contour applied across the active partials. Horizontal node position selects a point in the partial range. Vertical position sets level and polarity.

Count sets the number of active partials from 8 to 128.

Distribution changes how partials are distributed through node setup.

Odd/Even changes the balance between odd and even harmonics.

Offset moves partial frequencies away from exact harmonic multiples.

Wave Warp moves the partials closer and further apart in a wave pattern.

Weirdness reduces the distance between partials in a rather weird way. Opens for some controlled detuning setups.

Lock keeps its parameter fixed while other slot values are recalled or interpolated.

X-Voice FM uses the preceding voice as a linear-FM source. FILT uses its filtered pre-amplifier signal; OSC uses its oscillator signal.

Shift-drag node
Lock movement to the first detected axis.
Option/Alt-drag node
Scale the complete node shape vertically. Crossing zero inverts it.
Double-click node
Set its vertical value to zero without changing its horizontal position.
03

Slots and Live View

Eight oscillator slots around the partial editor

Eight slots store separate node shapes and partial-control states. Enabled slots form the path used by sequencing, CC4, velocity position, and voice offset.

Ring segment shows which slots are active and which is being edited.

Slot solo is temporary and is not saved with the preset. It affects notes started after solo is enabled.

Live View follows the current slot position of an active voice and changes followed voice when the current one becomes stale.

Voice dots shows the active voices current amplitude, which one is currently used by live view, and toggles voices off and on.

Slot circle voice dots shows the movement across slots on the slot tracks by each of the eight voices.

Shift-click slot
Enable or disable the slot.
Double-click slot
Enable or disable the slot.
Cmd/Ctrl-click slot
Solo the slot. Repeat to clear solo; select another slot to move solo.
Cmd/Ctrl+C / Cmd/Ctrl+V
Copy or paste the selected slot.
04

Slot sequencer

Slot sequencer direction, clock, keyboard stepping, rate, and slew controls

The slot sequencer moves through enabled slots and interpolates their stored oscillator states. Rate and Slew determine when movement starts and how much of each step is used for interpolation.

Normal / Reverse / Pendulum / Mylife / Skips / Random define the slot order.

Internal / Host select the local rate or musical divisions from the DAW clock. Turning both off disables continuous clocking.

KBD->RST resets a voice to the sequence start on note-on.

KBD->NEXT advances the voice's starting position on note-on.

KBD->RST + KBD->NEXT runs one complete direction-aware revolution in a clocked mode and holds on the final step. When clocked mode is off, it goes one single step with duration set by slew time

Voice Offset distributes voices across different starting slots.

Key Track tracks internal-clock speed from note pitch.

Vel->Pos maps note velocity to each voice's slot position when continuous clocking is off.

CC4 sweeps each voice across the enabled slots when clocking is off.

Slew sets the time or percentage for interpolation between slots. In Vel->Pos and CC4 mode, sets how much of each step or CC4 region is used for interpolation.

05

Pitch modulator

Pitch modulation LFO and noise controls

The pitch modulator applies a dedicated LFO or noise source to oscillator pitch. It runs independently from the modulation oscillator and filter-frequency modulator.

LFO / Noise selects between a sine wave or noise as modulator.

Amount sets pitch-modulation depth in semitones. The mod wheel is used as a multiplier and can add up to 1.25 semitones to the displayed amount.

Rate / Color sets LFO speed or the character of the noise source.

Fade In sets how long the modulation takes to reach its full depth.

Mono synchronizes the LFO across voices and removes per-voice Mod Speed discrepancy. With Mono off, every new note resets its own LFO phase.

Key On / Key Off selects whether modulation and its fade begins at note-on or note-off.

06

Modulation oscillator

Modulation oscillator waveform, rate, fade, and destination controls

The modulation oscillator is a separate per-voice source for audio-rate and low-frequency modulation. Its rate can be free-running or derived from the played note.

Sine / Saw / Pulse / S/H / Noise select the oscillator shape. Non-sine shapes are smoothed when used for amplitude modulation.

Rate sets the free-running frequency.

Fine adds fine adjustment to the modulation-oscillator frequency.

Key Track derives oscillator rate from note pitch and follows the selected PB range.

Fade In sets the modulation fade time.

Key On / Key Off selects whether modulation and its fade begins at note-on or note-off.

Filter FM applies the oscillator directly to filter frequency.

Osc TZFM applies linear through-zero frequency modulation to the additive oscillator.

Amp AM applies amplitude modulation.

Crush-Rate modulates the bit-crusher sample rate.

07

Bit Crusher

Bit crusher rate, bit depth, and key tracking controls

The bit crusher reduces signal resolution through independently controlled sample-rate reduction and bit-depth reduction. It is placed before the filter, so the filter can shape its artifacts.

Rate sets the crusher sample rate. Lower values produce more sample-rate reduction.

Bits sets the output bit depth from 24 down to 4 bits.

Key Track scales the crusher sample rate from note pitch.

08

Filter

Filter and filter frequency modulation controls

The state-variable filter provides low-pass and band-pass responses with selectable slope, resonance shaping, key tracking, velocity control, and parallel dry/wet operation.

LP / BP select the filter response.

6 dB / 12 dB / 18 dB select the filter steepness.

Resonance sets filter emphasis. The filter is not capable of self-oscillation.

Res Warp adds resonance-dependent drive.

Key Track tracks cutoff from note pitch.

Vel->Cutoff moves cutoff from note velocity.

Wet blends filtered and unfiltered output.

09

Filter frequency modulator

Filter frequency modulation LFO and noise controls

The filter-frequency modulator applies a dedicated LFO or noise source to cutoff. It is independent from the pitch modulator and modulation oscillator.

LFO / Noise selects between a sine wave or noise as modulator

Amount sets cutoff-modulation depth in semitones.

Rate / Color sets LFO speed or noise color.

Fade In sets how long the modulation takes to reach its full depth.

Mono synchronizes the LFO across voices and removes per-voice Mod Speed discrepancy. With Mono off, every new note resets its own LFO phase.

Key On / Key Off selects whether modulation and its fade begins at note-on or note-off.

10

Amplifier envelope and output

Amplifier envelope and output controls

The amplifier ADSR controls voice level. Velocity can scale the envelope response, and the output section provides final gain and parallel compression.

Attack sets the rise time from note-on.

Decay sets the time from the attack peak to the sustain level.

Sustain sets the held level.

Release sets the fade from the current voice level after note-off.

Vel Sens sets how strongly note velocity scales amplifier level.

Output sets final output gain.

Comp Mix blends a fixed compressor output with the untreated output.

11

Filter envelope

Filter envelope amount, velocity, and ADSR controls

The filter ADSR offsets cutoff independently for every voice. Its amount and velocity response are bipolar.

Attack sets the rise time from note-on.

Decay sets the time from the attack peak to the sustain level.

Sustain sets the held envelope level.

Release sets the return time after note-off.

Amount sets positive or negative cutoff modulation in semitones.

Vel Sens sets positive or negative scaling from note velocity.

12

MPE and MIDI control

MPE mode logo, pitch bend range, and voice controls

The logo button steps through three expression modes. The unlit state disables the additional MPE mappings. White and red use different pressure and slide assignments.

Grey mode is the most chaotic MPE mode, it affects a ton of parameters in confusing ways.

White mode distributes pressure and CC74/slide across several synthesis parameters for broad timbral movement.

Red mode uses CC74/slide to open the filter. Pressure controls per-voice amplitude above the envelope sustain floor.

Red mode, zero sustain follows pressure directly when attack and decay are at minimum. Release remains available.

Pitch bend follows the selected PB range.

Sustain holds active notes from MIDI CC64.

MTS-ESP applies tuning from a compatible tuning source.

13

Discrepancies

Per-voice discrepancy controls and randomize button

Discrepancies apply a stable set of differences to the eight physical voices. Every voice, including voice 1, has its own values. A control sets the permitted amount of variation; it does not generate continuous random modulation.

Tune offsets oscillator pitch independently for each voice, up to approximately one semitone in either direction at maximum.

Wave offsets the horizontal and vertical positions of the partial-editor nodes while preserving their order.

Position offsets each voice along the active slot path. The offset is added to sequencer, CC4, velocity-position, and voice-offset movement.

Harmonic varies partial count, harmonic distribution, and the odd/even balance.

Disharmonic varies partial offset, wave warp, and weirdness.

Mod Speed scales per-voice pitch-LFO, filter-LFO, and modulation-oscillator rates. It also contributes to amplifier- and filter-envelope timing. Mono LFO mode bypasses its speed difference for that LFO.

Mod Depth scales filter-LFO depth, filter-envelope amount, and the modulation oscillator's Filter FM, Osc TZFM, Amp AM, and Crush-Rate destinations.

Bit Crush varies bit depth, sample rate, and crusher key tracking.

Filter Env varies amplifier-independent filter-envelope attack, decay, and release timing.

Filter varies cutoff, resonance, resonance warp, response, and key tracking for each voice.

Amp Env varies amplifier-envelope attack, decay, and release timing.

Level varies voice output level before the final mix.

Stereo places voices at different positions in the stereo field.

Dice generates a new complete set of stable per-voice values. The set is stored with the preset and remains unchanged until another throw or another preset is loaded.

Zero settings bypass the corresponding discrepancy offsets even though the stored random values still exist.

White MPE mode uses the same per-voice values to distribute CC74/slide across slot position, node shape, harmonic distribution, odd/even balance, partial wave warp, and weirdness. This response can therefore change after a dice throw even when the discrepancy sliders are at zero.

14

Presets and editing shortcuts

Preset navigation, name, and save controls

The preset name display opens the browser. Preset names come from filenames; the folder and refresh controls support external renaming and deletion.

Name generates a preset name.

Save writes the current state. Saving the init patch first generates a name automatically.

Factory / User / Starting Points / Favorites filter the preset browser. Favorites and versioned-save settings are stored globally.

Versioned Save writes the next free numerical suffix only when the current preset is dirty.

Folder opens the preset directory for external renaming or deletion.

Refresh reloads filenames and deletions made outside the plugin.

Shift-click preset arrow
Move ten presets.
Cmd/Ctrl-click preset arrow
Move to the first or last preset.
Cmd/Ctrl+Z
Undo the previous edit gesture.
Cmd/Ctrl+Shift+Z
Redo the previous edit gesture.
Double-click control
Reset to the initial-patch value.
Option/Alt-wheel
Fine adjustment.
Shift-wheel
Coarse adjustment.
Cmd/Ctrl-wheel
Ultra-fine adjustment without magnetic snapping.

Recommended for

  • Animated additive pads that move through several harmonic states
  • Noisy and dissonant motion with rhytmic or key-following slot changes
  • Sound-design sessions where visual feedback can guide the results.

Fit and focus

Great fit for:

  • additive synthesis with a quick and simple interface
  • old polysynth behaviour without old polysynth hassle
  • harmonic exploration that stays visual and playful

Questions people ask

What is Partials & Discrepancies?

It is an 8-voice additive synth built around a sinplified abstraction for partial control, where each voice has up to 128 partials, slot-based timbre motion, and discrepancy controls that make the voices diverge from one another.

How is it different from a conventional synth?

It puts the additive structure, slot motion, and voice divergence right in front of you, so the sound can get weird while the workflow stays readable.

Who is it for?

It is for synth users who want something more adventurous than a standard polysynth, but still immediate enough to quick sound design and experimentation when you need fast results.

Does it support MTS-ESP and MPE?

Yes. Partials & Discrepancies supports MTS-ESP for microtonal and alternative tuning setups, and it is also MPE compatible, with 3 MPE modes, if you want a more expressive controller workflow.

Compatibility

macOS 12+, Windows 10/11
macOS: AU/VST3, Windows: VST3

Partials & Discrepancies also supports MTS-ESP and is MPE compatible.

These plugins use detailed real-time processing and are happiest on reasonably recent CPUs, especially when several instances are running at once.

Preset system

A shared walkthrough of the Unusable preset system, with practical tips for saving, naming, organizing, and moving between ideas.

Bundle option

Also available in bundle form

If this plugin fits your workflow, there is a good chance one of the bundles will fit even better and reduce total spend.

Full Suite v2

All unusable tools in one package, built to surprise, inspire, and keep the creative process moving.

€179.00€438.00incl. 25% VAT

Includes 15 products.