DonutStudio's tuning system is built around a simple idea: an interval is not just a distance in cents. It can be a relationship.
In ordinary 12-TET MIDI, a note says: play this semitone. In DonutStudio, a note can also say: be 3/2 above that note, be 5/4 above this root, or snap to the simplest ratio that explains this musical moment. That difference is the core of the app's tuning model.
After auditing the built-in interval sets, several things became clearer. Some old names were misleading. Some presets were doing useful work but needed more honest labels. And some tuning ideas that sound similar on the surface are actually different tools.
DonutStudio Is Ratio-First
DonutStudio's built-in interval presets use exact rational ratios: 1/1, 5/4, 3/2, 7/4, 45/32, and so on.
That makes them different from historical keyboard temperaments like quarter-comma meantone. A temperament fixes a set of pitch classes and compromises some intervals so that a keyboard can play in many keys. A ratio set gives the program exact harmonic relationships it may use when creating or interpreting links between notes.
That distinction matters. True quarter-comma meantone has a fifth of about 696.578 cents. It is not the pure ratio 3/2 = 701.955 cents. So quarter-comma meantone is not a ratio preset. It belongs in a cent-valued temperament or Scala-style path, not inside DonutStudio's ratio preset system.
The audited preset that used to be called Quarter Comma Meantone was actually a 5-limit chromatic just-intonation set, so it was renamed accordingly.
The Default: 5-Limit JI Chromatic
The normal default is now 5-limit JI (chromatic). It contains the conservative 5-limit vocabulary: 1/1, 16/15, 9/8, 6/5, 5/4, 4/3, 45/32, 3/2, 8/5, 5/3, 9/5, 15/8, and 2/1.
This is a good default because it gives pure major thirds, minor thirds, fourths, fifths, sixths, and common sevenths without forcing septimal color into ordinary imported MIDI.
The older name Just Intonation was too vague. Almost every ratio preset in DonutStudio is some kind of just intonation. The more specific name tells the truth: this is a 5-limit chromatic ratio vocabulary.
5-Limit Plus Septimal Tritone
DonutStudio also keeps a related set: 5-limit JI + septimal tritone.
This is mostly 5-limit, but its tritone uses 7/5. That is a real and beautiful interval, but it is not a generic tritone. It is a septimal tritone.
The audit made this distinction important because a 12-TET tritone can mean different harmonic things: 45/32 as a 5-limit augmented fourth, 64/45 as a 5-limit diminished fifth, or 7/5 as a septimal tritone. Those should not be silently collapsed into one label.
The septimal tritone set is useful as a color preset, but it is not the safest default for converting a full 12-TET song into dynamic JI.
Selected Limits
A phrase like 7-limit JI can sound like it names a complete finite object. It does not. Full 7-limit just intonation is infinite. You can keep generating more ratios using primes up to 7 forever.
So DonutStudio uses names like 7-limit selected JI. That wording matters. It means the preset is a curated subset of useful 7-limit relationships, not the totality of 7-limit harmony.
The same principle applies to 11-limit and 13-limit collections. They are selected pitch vocabularies, not complete mathematical universes.
Pythagorean, Wendy Carlos, and Partch
The audit also corrected several historical names. The old Pythagorean preset was not a full chromatic Pythagorean tuning. It was a Dorian-flavored diatonic selection, so it became Pythagorean Dorian. A full chromatic 3-limit option can be named Pythagorean Chromatic (3-limit).
The old Wendy Carlos Super Just preset actually matched Wendy Carlos' Harmonic scale, so it was renamed Wendy Carlos Harmonic. The real Super Just set is a separate preset.
The Partch 43-tone Genesis set is different again: it is a historically specific 11-limit scale world, not just a small chord vocabulary. DonutStudio keeps that kind of set available, but it should be understood as a named xenharmonic system rather than a generic import default.
Tenney Height
Several DonutStudio modes use Tenney height as a rough consonance measure. For a reduced ratio, H = log2(numerator * denominator).
Simple ratios have low Tenney height: 3/2 is simpler than 5/4, 5/4 is simpler than 16/15, and 16/15 is simpler than tiny comma-like ratios such as 81/80.
This is useful because it measures ratio complexity, not just cents distance. A small interval can still be complex. The syntonic comma 81/80 is only about 21.51 cents, but it is much more complex than a wide pure fifth 3/2. That is why DonutStudio can use Tenney height to ask which ratios are simplest.
Mode 1: Preset Intervals
Preset mode uses a hand-authored ratio vocabulary. This is the best mode when the user knows the harmonic language they want: 5-limit JI (chromatic), 7-limit selected JI, Pythagorean Dorian, Wendy Carlos Harmonic, Partch Otonality, or Partch Utonality.
Preset mode is explicit and stable. The ratios are known, named, and auditable.
Mode 2: Harmonic Series Count
Harmonic Series mode is the older overtone-based behavior. Instead of choosing from a curated ratio table, DonutStudio searches through harmonics up to a maximum count.
This is useful when the user wants the raw overtone world: 1, 2, 3, 4, 5, 6, 7.... It is direct, but it is not the same as a balanced scale or a chromatic preset. It is a harmonic search limit.
Mode 3: Lowest Tenney Count
Lowest Tenney Count asks for a number of interval classes and generates the simplest octave-folded ratios first.
For example, count = 12 means: give me 12 distinct octave-reduced ratios with the lowest Tenney height. This is root-relative. It answers the question: which intervals are simplest against the root?
That makes it useful as a maximum-consonance vocabulary generator, but it is not the same as optimizing a whole scale for every possible pair inside it.
Mode 4: Harmonic Window
Harmonic Window came from a more demanding question: if I want N notes, which set lets me stack the most mutually consonant chords?
We first explored this as an optimizer over all pairwise Tenney heights. The important result was that minimax pairwise Tenney kept rediscovering the same structure: contiguous harmonic or subharmonic windows.
So the implemented mode exposes that structure directly. The useful controls are count, start harmonic, and otonal / utonal.
Otonal uses a numerator window such as k/k, (k+1)/k, (k+2)/k, and onward. Utonal mirrors it as a denominator window such as top/top, top/(top-1), top/(top-2), and onward.
The count means distinct folded pitch classes. If the window hits an octave duplicate, DonutStudio keeps extending until it has the requested number of unique interval classes.
This mode is honest about what it is. It is not a mysterious Balanced Tenney black box. It is a harmonic window: the mathematical shape that appears when you try to keep the worst pairwise relationship inside a stack as simple as possible.
Otonal and utonal windows have the same consonance profile. They differ in spacing direction: one is the pitch-inversion of the other.
What Harmonic Window Is Not
Harmonic Window is not a transposable chord vocabulary. It is excellent for stacking notes around one implied fundamental, building overtone or undertone chord worlds, and exploring dense consonant sonorities.
But if the musical goal is to have the same chord vocabulary transpose smoothly across many roots, Harmonic Window is the wrong tool. That calls for a lattice or Tonnetz mode built from generators such as 3/2 and 5/4. That future mode should stay separate. A hybrid would compromise both goals.
12-TET Lowest Tenney Presets
DonutStudio also includes two fixed 12-TET-facing ratio presets: 12-TET Lowest Tenney JI (100c tolerance) and 12-TET Lowest Tenney JI (50c tolerance).
These are not the same as the free Lowest Tenney Count generator. They ask: for each 12-TET semitone region, which low-Tenney ratio fits best?
The 100c version uses a full semitone bucket: plus or minus 50 cents around the target semitone. The 50c version uses a stricter bucket: plus or minus 25 cents. These are useful for mapping ordinary MIDI notes into nearby JI ratios while still preserving the idea of 12 semitone regions.
Functional 12-TET JI
The deeper import problem is different again. A 12-TET MIDI note does not tell DonutStudio whether a tritone is 45/32, 64/45, or 7/5. It also does not tell whether a minor seventh wants 9/5, 16/9, or 7/4.
That is why a future Functional 12-TET JI mode should not be just another preset. It should be a Root Path Tune interpretation mode. Instead of asking what this semitone always means, it should ask: given this root, chord, frame, and surrounding musical context, which ratio best explains this note?
That lets DonutStudio stay conservative by default, using 5-limit ratios for ordinary material, while still allowing septimal colors when the local harmony supports them.
The Design Rule
The audit led to one useful rule: name the mode after the musical object it actually produces.
So: 5-limit JI (chromatic), not Quarter Comma Meantone. Harmonic Window, not Balanced Tenney Set. 7-limit selected JI, not Full 7-limit JI.
This keeps DonutStudio's tuning system musically legible. A composer should be able to look at a mode and understand what kind of harmonic world it creates.
Summary
DonutStudio now has several distinct ratio-source ideas: Preset Intervals for curated exact-ratio vocabularies, Harmonic Series Count for raw overtone search, Lowest Tenney Count for simplest root-relative folded ratios, and Harmonic Window for contiguous harmonic or undertone windows for consonant stacks.
Separately, the 12-TET Lowest Tenney presets are fixed semitone-bucket JI mappings, Functional 12-TET JI is a future context-aware import interpretation, and Tonnetz/Lattice mode is a future transposable chord vocabulary.
The important thing is that these are not competing names for one feature. They answer different musical questions. That is the point of a ratio-first composition tool: not to choose one tuning system forever, but to make the harmonic relationship itself editable.