SQUELCRUDE is a monophonic acid bass synthesizer specialized for TB-303 style squelching basslines. It features aggressive resonance and filter envelopes, slides and accents, and a step sequencer with selectable key and scale. In addition to basslines, it can also be used for leads, drones, and special sound effects.
SQUELCRUDE onto an instrument track in your DAW (or launch the standalone app if not using a DAW).01 ACID RIFF 303.CUTOFF and RESO in the FILTER panel. These two controls shape the characteristic acid squelch.DECAY in the ACID panel and ENV MOD in the FILTER panel changes the speed and depth of the squelch.SEQ ON in the bottom SEQUENCER panel, press RANDOM, and hold down a key on your keyboard.SUB is an independent sound source. Even if A and B levels are set to 0, SUB will still sound. Turn it up when you want to reinforce low-end weight.CUTOFF controls brightness, and RESO determines the intensity of the resonance peak.RESO all the way up causes the filter to self-oscillate, producing a tone even without audio input. This is by design. 30 DRONE is a preset that actively utilizes this behavior.ENV MOD sets the depth of the filter envelope. At 0 it behaves like a standard bass synthesizer; increasing it brings out the signature acid sound.DRIVE adds internal filter saturation, thickening the tone without altering the resonance response.KEY TRK) select how closely the filter tracks the played pitch (OFF / 50% / 100%).DECAY controls how quickly the filter squelch falls off, ACCENT controls intensity on hard-struck notes, SLIDE sets the pitch glide time, and VEL>CUT adjusts how much playing velocity affects brightness.SLIDE takes effect when notes are played overlapping (legato). Setting it to ALWAYS glides continuously between all notes.TONE controls overall brightness tilt, VOLUME controls output level, and PAN sets stereo positioning. You can monitor the output level with the vertical meter on the right edge of the MASTER panel.BYPASS is a button located below the MASTER panel that cuts the output. It is also linked to the DAW's bypass button.SUSTAIN to 0 creates snappy plucked sounds, while raising it produces sustained notes.> CUTOFF modulates the filter, and > PITCH modulates pitch.SYNC locks RATE to musical note divisions synchronized to the DAW tempo.DELAY sets the time from note strike until modulation begins.OD thickens the tone, HARD is aggressive, and FUZZ provides a crushed texture.MIX blends in the dry sound. Use it when you want to add distortion while preserving low-end definition.SEQ ON and hold down a key to loop a phrase rooted at that note.RANDOM automatically generates a phrase strictly within the selected scale. You can edit the steps manually after generation.ACC to toggle accents, click SLD for slides, and click GATE to cycle through Note → Tie → Rest.LENGTH (number of loop steps), SWING (shuffle delay), DENSITY (note density), ACCENT (accent amount), SLIDE (slide amount), and CUT DEPTH (MOD lane modulation depth).KEY (C–B) and SCALE are selected via dropdown menus. The ROOT / KEY buttons, RATE (1/8–1/32), and OCT (0 / ±1 / ±2) buttons are arranged on the right side of the SEQUENCER panel.NOTE / MOD toggle the grid display. The MOD view is a lane for drawing per-step brightness.Drawing per-step brightness (MOD lane).
Switching to the VIEW MOD button allows you to draw cutoff raises and cuts by dragging up and down on each step. Drag across horizontally to paint steps continuously, and double-click a step to reset it to neutral (no change).
How strongly the drawn values take effect is determined by CUT DEPTH, located on the far right of the SEQUENCER knob row (LENGTH / SWING / DENSITY / ACCENT / SLIDE / CUT DEPTH). If CUT DEPTH is left at 0, drawing in the lane produces no sound change. Raise CUT DEPTH before drawing.
The lane contents are saved with your song (project). Pressing RANDOM will not erase the lane.
75% / 85% / 100%. Use this if the entire window does not fit on small laptop screens.Two key matching modes.
In ROOT mode, the played note becomes the tonic. Every key you play produces a riff with the same harmonic relationship, making it ideal for jamming without worrying about musical keys.
In KEY mode, the musical scale is fixed by KEY and SCALE, and the played note determines the phrase starting position. The phrase stays strictly within your song's key, making this mode ideal for playing along with chord progressions. For example, with KEY set to A and SCALE set to MINOR, playing C will only sound notes in the A natural minor scale.
A to save the current sound to A, and B to save to B (A lights up purple, B lights up pink).A and B can be taken from different presets. You can use a workflow like: Save A → Load another preset → Save B. Loading presets does not erase stored A / B snapshots.
Storage behavior also differs: A / B snapshots are saved with your song (project) and restored when reopened. They are not stored inside preset files.
Sets the frequency where the filter begins cutting off sound. Lower values sound darker and muffled, while higher values sound brighter. The acid squelch is created when the envelope moves upward starting from this position.
ENV MOD increases the sweep range of the squelch.800 HzEmphasizes the frequencies around the cutoff. Higher values produce a sharper, more pronounced acid character.
55 %The depth of the filter envelope sweep. This is the most crucial parameter defining the character of this instrument.
0 % it behaves like a standard bass synthesizer; increasing it brings out the signature 303 character.60 %Controls how quickly the squelch decays. Shorter times sound snappy, while longer times sound sticky and prolonged.
250 msControls how dramatically accented notes stand out. Volume, brightness, and sharpness change simultaneously.
60 %The time over which pitch glides between notes. Takes effect when notes are played overlapping (legato).
SLIDE MODE to ALWAYS glides between all notes even when not overlapping.60 msThe three vertical buttons on the right edge of the FILTER panel (labeled KEY TRK). Makes the filter cutoff follow the played keyboard pitch. Has three settings: OFF / 50% / 100%.
100%. Low bass becomes substantially smoother and more settled.50%The knob located on the far right of the SEQUENCER knob row. Determines how strongly the brightness curves drawn in the MOD lane affect the cutoff.
0 %Determines the musical notes used by phrases. KEY (C–B) and SCALE are chosen via dropdown menus, and the ROOT / KEY buttons toggle the mode. RANDOM picks notes exclusively from the selected scale.
ROOT: The played note becomes the tonic.KEY: Notes are constrained by KEY and SCALE, and the played note sets the phrase starting position. Stays strictly in key.MINOR / C / ROOTSCALE can be selected from 12 types:
MINOR / MAJOR / DORIAN / PHRYGIAN / MIXOLYDIANHARM MINOR (Harmonic Minor) / MEL MINOR (Melodic Minor) / PHRYG DOM (Phrygian Dominant: has a Spanish flavor, great for acid and psychedelic riffs)PENT MIN (Minor Pentatonic) / PENT MAJ (Major Pentatonic) / BLUESCHROMATIC (All 12 semitones; phrases can drift outside conventional keys)Defines phrase tendencies: note density, accent frequency, and slide frequency.
RANDOM again. The phrase tendency evolves while you listen, allowing you to fine-tune it by ear.75 % / 30 % / 25 %Morphs smoothly between two stored sound snapshots, A and B. Moving the slider physically moves the knobs on the screen.
A or B again. This folding occurs only during manual slider movements; it is not triggered during DAW automation playback, ensuring saved A / B snapshots are never altered during playback.0 % (Neither A nor B saved)OSC A WAVE: SAW
CUTOFF: 400 Hz
RESO: 75 %
ENV MOD: 70 %
ACID DECAY: 220 ms
ACCENT: 80 %
AMP SUSTAIN: 0 %OSC A LEVEL: 60 %
SUB: 90 %
CUTOFF: 200 Hz
RESO: 20 %
ENV MOD: 20 %
KEY TRACK: 100%
DIST TYPE: OFFSEQ ON: On
ROOT/KEY: KEY
KEY: Song Key
SCALE: MINOR
RATE: 1/16
DENSITY: 75 %1. Create a dark patch (lower CUTOFF / lower RESO) -> Save to A
2. Switch presets or tweak toward a bright sound
(higher CUTOFF / higher RESO / higher DIST AMOUNT) -> Save to B
3. Move the MORPH slider slowly from 0 % to 100 %In addition to manual movement following song arrangements, you can also stop halfway to use an intermediate hybrid tone between A and B as a new starting point. If you like the intermediate sound, you can save it directly as a preset.
If low notes sound harsh or overly piercing in the highs, set KEY TRACK to 100%. Lower notes will lower the cutoff accordingly, preventing harshness in the bass register. 09 DEEP SUB / 10 MUTED BASS / 03 TB CLASSIC use this setting.
| Item | Details |
|---|---|
| OS | Windows 10 / 11 (64bit) macOS 11 or later (Apple Silicon / Intel) |
| Formats | Windows: VST3 plugin / Standalone Mac: VST3, AU plugin / Standalone |
| Supported DAWs | DAWs supporting VST3 or AU (verified in Ableton Live) |
| Polyphony | Monophonic (1 voice at a time) |
| Sample rates | 44.1 kHz - 192 kHz |
| Latency | A slight latency is introduced for audio quality (automatically reported to DAW so recording alignment is preserved) |
| Window size | 1100 × 864 px (UI scale 75% / 85% / 100% selectable via background right-click) |
SQUELCRUDE.vst3 folder to the following location:C:\Program Files\Common Files\VST3\
SQUELCRUDE.exe directly. On first launch, you will need to configure your audio device and MIDI input settings.SQUELCRUDE.vst3 to ~/Library/Audio/Plug-Ins/VST3/, and copy SQUELCRUDE.component to ~/Library/Audio/Plug-Ins/Components/. To use as standalone, copy SQUELCRUDE.app to your "Applications" folder (where ~ represents your home folder. In Finder, open the "Go" menu, choose "Go to Folder...", paste the path, and press Return).cd ~/Library/Audio/Plug-Ins
xattr -dr com.apple.quarantine VST3/SQUELCRUDE.vst3
xattr -dr com.apple.quarantine Components/SQUELCRUDE.component
xattr -dr com.apple.quarantine /Applications/SQUELCRUDE.appWindows: Delete the C:\Program Files\Common Files\VST3\SQUELCRUDE.vst3 folder. To completely remove settings and user presets, delete %APPDATA%\Tonecraft Tokyo\SQUELCRUDE\.
Mac: Delete the copied SQUELCRUDE.vst3, SQUELCRUDE.component, and SQUELCRUDE.app files. To also remove settings and user presets, delete ~/Library/Tonecraft Tokyo/SQUELCRUDE/.
C:\Program Files\Common Files\VST3\ (or under ~/Library/Audio/Plug-Ins/ on Mac), and perform a plugin rescan in your DAW. If you copied files while your DAW was running, changes may not take effect until restarted.BYPASS is turned on or MASTER VOLUME is turned all the way down. In standalone mode, also check your audio device and MIDI input settings.RESO is turned all the way up, the filter self-oscillates and continues ringing without audio input. Lower RESO to stop the self-oscillation.SUB is an independent sound generator. Set SUB level to 0 as well.ROOT/KEY to KEY, and match KEY and SCALE to your song. In ROOT mode, the played note is treated directly as the tonic.CUT DEPTH is set to 0. Raise CUT DEPTH. The lane draws the modulation shape, but this knob determines how strongly it takes effect.A and B indicator lights must be lit. If either snapshot is missing, there is no destination to morph toward and nothing will happen.