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

1.5.1 - 2026-10-28

Preset Workflow

  • Cmd/Ctrl-clicking Name uses the host track name when available. Existing names get the next free numbered suffix; unsupported hosts leave the name unchanged.
  • Optimized preset meta data handling and refresh process after renaming presets.

MIDI Timing And Slot Recording

  • Notes and controllers are now applied at their sample positions within the audio buffer. Short notes contained within one buffer are rendered instead of collapsing before audio is generated.

1.5.0 - 2026-10-22

User Interface

  • The user interface has a slightly adjusted color scheme. Adding blue to the background and the tracks of filter modulation knobs.
  • All the oscillator controls have been arranged below the spectrum editor (earlier called wave editor). The harmonic controls are moved further to the left, and disharmonic controls are moved further to the right. The fm controls and some new controls are placed in the middle.
  • Discrepancy controls have been refined and can now be clicked to change values
  • Pitchbend range has been moved to the absolute left.
  • Some controls have been changed to logarithmic scaling to give more control in the lower registers.

New Filter

  • A new filter called East has been added alongside the original filter, now called West.
  • East can self-oscillate and follow the played pitch. It can be used as a sound source as well as a filter.
  • If shift-scroll is used on the filter cutoff, the cutoff snaps to key.

New Oscillator Controls

  • Detune adds a second, oppositely detuned copy of the additive oscillator for width and beating.
  • Smear is a tuned delay line that keeps ringing after the oscillator changes. With the slot sequencer, it can be used to make Karplus-Strong-style sounds.
  • Detune and Smear can have separate settings for each slot, with locks if you want the same value across the sequence.
  • Wave Clear and Wave Random are now labeled Spectra Clear and Spectra with a randomize icon. The controls work as before; the names better describe what they edit.

Ring Modulator

  • The existing bit crusher section can now be switched to a ring modulator. The controls then set ring-modulation rate and depth instead of bit depth and sample rate.
  • With key track at 100%, the ring-modulation rate follows the played pitch.
  • The modulation oscillator can also move the ring-modulation depth.

Modulation Oscillator

  • The modulation oscillator can now run in time with the host or reset its cycle on key down.
  • With Noise and Key Track selected together, it produces tuned noise that follows the notes you play, rather than unpitched noise.

Glide And Legato

  • Notes can now glide between pitches. Turn on Legato to glide only when notes overlap.
  • In polyphonic mode, each new note glides from the closest held note; notes played together as a chord start independently.

Presets

  • Added 41 new factory presets.
  • You can now make a Program Change map from the presets currently shown in the browser, in their current order. Filter or sort the list first to choose what the map contains.
  • Switching presets no longer briefly plays voices and sequencer movement left over from the previous patch.

Voice Stealing

  • When all voices are in use, notes are replaced more smoothly. This reduces clicks when playing dense passages or using long releases.

1.4.2 - 2026-10-11

Preset system

  • Reduced sudden CPU spikes due to preset analysis rescans running scheduled - rescans are only triggered by refresh icon clicks now.

1.4.1 - 2026-10-08

Patch Browser

  • Added ability to generate a zipped preset archieve from any filtered preset list.
  • Added a preset counter indicating the number of presets in the current view.

Interface

  • Added a resize icon and per-instance window-size recall.

1.4.0 - 2026-09-24

Preset Browser

  • Added preset metadata with automatic categorization based on the settings in each patch.
  • Presets can be filtered by Type, Character, Motion, and Performance.
  • Added sorting by name, save date, and preset type.
  • Added preset banks for organizing Factory, Starting Point, User, and custom preset collections.
  • Metadata and bank assignments can be edited from the preset browser without changing the sound of the patch.
  • The browser now opens at the currently selected preset.

Oscillator Filter FM

  • Added Osc Filter FM, which uses the additive oscillator to modulate the voice filter.
  • Osc Filter FM is stored independently in every oscillator slot and slews with the slot sequencer.
  • Added a lock for keeping Osc Filter FM fixed across all slots.
  • Osc Filter FM follows slot randomization, copy, paste, and Live View.

Slot Sequencer

  • Improved full-slew movement in One Revolution mode so transitions continue without pausing briefly at each slot.
  • Disabling One Revolution mode now releases voices held at their final slot and returns them to normal clocked movement.
  • Switching Internal or Host clock on or off now resets the sequencer to the first enabled slot.
  • The Rate control is now dimmed when neither Internal nor Host clock is active.

Interaction And Interface

  • Cmd/Ctrl+scroll is now twice as fine and uses continuous movement without detents or magnetic values.
  • Added a visible resize handle in the lower-right corner of the interface.
  • Fixed a webview2 issue on Windows making plugin resize blurry.

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.
Free additional patch banks for download

Installing additional Preset Banks

Trajectoire's illustrated guide to installing his free Quasicrystal bank (or any other bank) and finding it in the preset browser.

Type
PDF guide
Requires
Partials & Discrepancies 1.4.0+
Author
Trajectoire
Download PDF

All Partially Dirty

21 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 ten behavior parameters, so the sound can move between harmonic and more broken states. Offset, Wave Warp, and Weirdness push the partials away from harmonic spacing, while the slot sequencer, voice offset, and discrepancy controls let voices drift and diverge in either musical or more chaotic ways.

It can do animated pads, unstable leads, brittle static digital sounds, and inharmonic sweeps. The architecture is kept 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 playthrough of around 30 presets from Partials & Discrepancies v1.5.0, with fully dry sound and some of the update's new features shown on screen.

A no-talking run through the 24 new factory presets included with Partials & Discrepancies 1.4.0.

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.

Glide sets the time used to move from one note pitch to the next. In polyphonic mode, a new note starts from the closest held note.

Legato limits glide to overlapping notes. Notes played together within the chord window start at their own pitches.

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.

When all voices are occupied, voice stealing fades out the replaced voice before starting the new note.

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.

Detune adds an oppositely detuned copy of the additive oscillator for beating and width. It is stored separately in each slot.

Smear feeds the oscillator into a tuned delay line. Its tail can ring across slot changes for plucked, Karplus-Strong-style sounds.

Osc Filter FM uses the additive oscillator to modulate the voice filter. It is stored separately in each slot.

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.

Spectra Clear / Spectra randomize clear or randomize the active slot's partial spectrum. These are the former Wave Clear and Wave Random controls.

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, including Detune, Smear, and Osc Filter FM. 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. The Rate control has note-related frequency detents in this mode.

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 source for audio-rate and low-frequency modulation. It can run freely, track the played note, or sync to the host clock.

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

Rate / Sync Rate sets frequency when running freely or a musical division when Sync is active.

Fine adds fine adjustment to the modulation-oscillator frequency.

Key Track derives oscillator rate from note pitch and follows the selected PB range. With Noise selected, it produces tuned band-pass noise that follows the note.

Sync locks the oscillator to the DAW clock. Sync and Key Track are alternative rate modes.

KBD->RST restarts a synced waveform on note-on. With free-running S/H, it generates a new starting value.

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 / Ring Depth modulates bit-crusher sample rate in Bit mode or ring-modulation depth in Ring mode.

07

Bit Crusher and Ring Modulator

Bit crusher section with rate, bit depth, and key tracking controls

This stage sits before the voice filter. Bit mode reduces sample rate and bit depth; Ring mode multiplies the oscillator by a separate carrier for pitched sidebands.

Bit / Ring switches between the original bit crusher and the new ring modulator.

Rate sets the crusher sample rate in Bit mode or the carrier frequency in Ring mode.

Bits / Depth sets bit depth from 24 down to 4 bits in Bit mode or the amount of ring modulation in Ring mode.

Key Track scales the crusher sample rate or ring carrier frequency from note pitch.

08

Filter

Filter and filter frequency modulation controls

The original filter is now called West. The new East filter uses the same LP/BP, slope, cutoff, and wet controls but can self-oscillate at high resonance.

West / East select the original West filter or the new, self-oscillating East filter.

LP / BP select the filter response.

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

Cutoff sets filter frequency. In East mode with high resonance, it also sets the self-oscillation pitch.

Resonance sets filter emphasis. East can self-oscillate at high settings; West retains the earlier response.

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.

Shift-wheel Cutoff
Snap cutoff to note-related frequency detents. A detent holds briefly before further scrolling moves past it.
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 or Ring Depth destination.

Bit Crush varies bit depth, sample rate, and key tracking in Bit mode. In Ring mode, it varies ring depth, carrier rate, and 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. Presets can be organized by bank and metadata, filtered or sorted, and used to build a Program Change map.

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.

Type / Character / Motion / Performance filter presets by their automatically detected or manually edited attributes.

META edits a preset's bank and attribute overrides without changing its sound.

PC Map Current List writes up to 128 presets from the current filtered and sorted list to the Program Change map.

Export Listed Presets exports the currently filtered preset list as a zip.

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 control's default value, usually its initial-patch value.
Option/Alt-wheel
Fine adjustment.
Shift-wheel
Coarse adjustment.
Cmd/Ctrl-wheel
Ultra-fine adjustment without magnetic snapping.

Questions no-one asked:

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

Two synthesizers and all fourteen effects in one package. Currents & Nostalgia is sold separately.

€179.00€496.00incl. 25% Danish VAT€143.20 excl. VAT

Includes 16 products.