Microtonal instruments & effects
A complete sound engine
Synths, soundfonts, plugin instruments, and effects are part of the composition environment. Pro is for the transformation layer: samples, vocals, and pitch-aware audio workflows.
- Sybil-16 Virtual Analog. 16-voice VA synthesizer named after the Oracle at Delphi. Three oscillators, multimode filter, dual envelopes, LFO matrix, character drive, built native in C++ for sample-accurate per-note tuning.
- OP-7 FM Synthesis. Six-operator FM synth with 32 algorithms and 20,800+ DX7-compatible .syx presets: bell tones, brass stacks, bass, leads. OP-7's live front-panel editor exposes every operator, and a full mod matrix lets you route envelopes and LFOs anywhere. Drop in a vintage patch or build your own, and either way it retunes through the harmonic graph.
- SF2 / SFZ Soundfonts. Sfizz-based SFZ engine with float per-note tuning patches, plus full SF2 support. GeneralUser GS, MuseScore General, FluidR3 GM, SGM, VCSL, Karoryfer: 1,300+ instruments, all retuned in real time.
- DiffSinger Neural Vocals. Type lyrics in the piano roll, draw gender, breathiness, tension, energy, expressiveness, and velocity curves, then render in the background. The vocal follows the harmonic graph.
- UTAU Sample-Based Vocals. Load UTAU voicebanks, edit phonemes and OTO timing, and tune every note through the same JI graph as the rest of the arrangement.
- WORLD Vocal Resynthesis (Pro ยท beta). Re-tune a real voice. Drop in a recorded vocal and DonutStudio analyzes it with the WORLD vocoder, then resynthesizes it under a dedicated vocal pitch editor. Pull the contour onto exact just-intonation ratios and the recording follows the harmonic graph note for note, the same as every synthesized instrument.
1,300+ instruments, ready to play
An in-app browser pulls SF2 banks, SFZ libraries, and FM patches straight into your project. Every starter instrument runs through the harmonic link graph at floating-point precision.
GM-compatible soundfonts
GeneralUser GS, MuseScore General, FluidR3 GM, SGM. Complete General MIDI banks ready to play, with auditioning and one-click download from the in-app library.
SFZ libraries
VCSL, Karoryfer, DonutStudio Misc: orchestral, ethnic, electronic, percussion. Modern SFZ format with full velocity layering, round-robins, and articulation switching.
Microtonal playback
A patched sfizz engine accepts floating-point note values, so any soundfont pitches smoothly to any harmonic ratio.
20,800+ FM presets
A DX7 .syx archive of bell, bass, lead, pad, arp, and percussion patches. Drop a patch in and retune it through the harmonic graph.
In-app store
Browse, audition, and download libraries. New ones appear automatically as the catalog grows.
Three ways to sing
Three vocal engines: neural (DiffSinger), concatenative (UTAU voicebanks), and resynthesis of real recordings (WORLD, beta). All of them get the Pro transformation features, and all retune to your chord progressions like every other instrument.
MTS-ESP: retune any plugin
The harmonic graph reaches past DonutStudio's own synths. DonutStudio acts as an MTS-ESP master, retuning every MTS-aware plugin in the session live, and as a client, so it can receive tuning too. DonutStudio Pro's Modular Grid can host a third-party synth as a patch node, carrying your just-intonation ratios straight through it. Hosted VST3 and CLAP instruments run as crash-isolated nodes with their own embedded GUIs (sandbox is beta, opt-in).
The sampling layer: your audio, retuned (Pro)
Pro applies the harmonic graph to recorded sound. Drop a sample onto a note, stretch its timing without changing pitch, or slice it at transients. Each result follows the note's exact ratio.
Per-note sample overlay
Lay an audio sample over any note in the piano roll. It plays at the note's pitch and the note's tuning, so a single recorded hit becomes a chromatic, microtonal instrument that follows your chord progressions.
Signalsmith time-stretch
Stretch and compress samples in time independent of pitch, with the Signalsmith stretch engine. Lock a loop to tempo without the chipmunk artifacts.
Slicing & transients
Detect transients and slice samples into playable hits, ready to retune, rearrange, and trigger across the keyboard.
Sample browser
Audition, tag, and organize your sample library with inline metadata editing, then drag straight onto a note.
480+ Airwindows effects
Chris Johnson's Airwindows suite ships built in, a complete library of console emulations, saturation, EQ, dynamics, reverbs, tape, modulation and more. Use them per-track, on buses, or on the master. It's the same C++ Chris distributes as VST/AU plugins. Alongside them, DonutStudio ships its own Donut Devices, the clean, tempo-synced, surgical utilities that round out the suite (below).
Console emulations
Discrete summing models like Capacitor, ToTape, and Console7 imprint analog character across the entire mix. The same Airwindows code top engineers use behind the desk.
Saturation & tone
Density, ToVinyl, and IronOxide bring vintage warmth, tape modeling, and transformer color to every track.
EQ & filters
Surgical and musical EQs alongside vibe-driven tone shapers like Air, Bass, and Treble, with a color all their own.
Dynamics
Compressors, limiters, expanders, and gates, including the Pressure series for transparent leveling and the Logical series for surgical control.
Reverb & space
Bricasti, Cathedral, Hall, and Reverb-1 through 4, from short rooms to infinite tails, designed to sit in a mix.
Per-track, per-sample, master
Drag-to-reorder effect chains anywhere they make sense: on a single sample, on the channel, on a group bus, or on the master. Native C++ throughout, with no plugin-format overhead.
Donut Devices: the clean utilities that round out the suite
Airwindows is a character and coloration suite. It leaves three things a default DAW gives you: clean surgical effects, host-tempo sync, and visual-feedback dynamics. Donut Devices fill those gaps. They're DonutStudio's own native effects, in their own "All Donuts" tab: the clean tools a producer expects to be there.
Clean modulation
DonutChorus, DonutFlanger, and DonutPhaser are the standard, transparent modulation effects, where Airwindows offers only vibey versions. Quadrature LFOs, bipolar feedback, multi-stage allpass, stereo throughout.
Tempo-synced delay
DonutDelay is a ping-pong delay locked to host tempo, with time set as a musical note division. Airwindows has zero tempo-aware delays, so this is the one you reach for.
Clean dynamics
DonutLimiter (look-ahead brickwall), DonutGate (with sidechain key and hold), and a true SidechainCompressor for the classic kick-ducks-bass pump, each with a gain-reduction readout.
Routing utilities
DCOffset, LatencyTrim, ChannelSwap, PolarityInvert, and a BitCrusher with optional TPDF dither handle the unglamorous jobs. Drop any of them anywhere in the chain.
Transform audio too
DonutStudio includes the composition engine, instruments, effects, and export. Upgrade when you want the harmonic graph to control vocals, samples, and recorded audio directly.