If you’ve spent any time in music theory circles online, you’ve probably heard the term “microtonal” thrown around — maybe alongside clips of strange-sounding guitars or keyboard instruments with too many keys. It can seem intimidating, like you’d need a mathematics degree just to understand what’s going on. But there’s one microtonal tuning system that’s genuinely easy to get into if you already know your music theory: 19-tone equal temperament, also called 19edo, 19tet, or 19et.
This guide is written for musicians who know their scales, chords, and intervals but have never seriously explored tuning systems outside the standard 12-tone equal temperament (12edo) we all grew up with. By the end, you’ll understand what 19edo is, why it sounds the way it does, how to think about it, and how to start making music with it.
What Even Is Equal Temperament?
Before getting into 19edo specifically, let’s make sure we’re on the same page about what “equal temperament” means.
In 12edo — the tuning system used by virtually all Western music today — the octave is divided into 12 equal steps, each called a semitone. Every adjacent pair of notes has the same frequency ratio. This is a compromise: pure, “just” intervals (the ones that sound maximally consonant because of how their overtones align) don’t divide the octave into equal slices, so 12edo slightly detunes most intervals to make everything fit neatly.
The tradeoff is worth it in 12edo: you can play in any key and everything sounds equally good (or equally impure, depending on your perspective). The major third in 12edo, for instance, is about 14 cents sharper than a pure major third — enough that you can hear beating if you listen carefully on a sustained organ chord.
Now here’s the key idea: there’s nothing magical about 12. You can divide the octave into any number of equal parts. 19edo divides it into 19.
The Basics: What Is 19edo?
In 19edo, each step of the scale is about 63.2 cents wide (a cent being 1/100th of a 12edo semitone). That means a 19edo “semitone” is actually smaller than a 12edo semitone — roughly two-thirds the size. The octave still closes perfectly at 1200 cents, just with more steps along the way.
Here’s why that matters musically: 19edo approximates many of the same pure intervals that 12edo does, but with different — often better — accuracy. Specifically:
The major third in 19edo is about 379 cents, versus the pure 5/4 ratio at 386 cents. That’s only about 7 cents flat — noticeably closer to pure than 12edo’s major third, which is 14 cents sharp. If you’ve ever heard the difference between an organ tuned in meantone and one tuned in modern equal temperament, you’ve already heard something close to this improvement.
The minor third in 19edo sits at about 316 cents, almost perfectly matching the pure 6/5 ratio at 315.6 cents. That’s essentially just intonation.
The perfect fifth is about 695 cents — only 7 cents flat of the pure 3/2 ratio at 702 cents. In 12edo the fifth is only 2 cents flat, so 19edo’s fifth is noticeably less pure. This is the main acoustic tradeoff you’re making.
In practice, 19edo’s major and minor thirds sound strikingly smooth and pure compared to 12edo, while its fifths have a slight “waver” that most listeners notice if they’re listening for it. Whether that’s a problem or a feature is largely a matter of taste and context.
This Isn’t New — It’s Older Than 12edo
One of the most surprising things about 19edo is how old it is. Interest in this tuning goes back to the 16th century, well before 12edo became the standard.
In 1558, French composer Guillaume Costeley wrote a chanson called Seigneur Dieu ta pitié with explicit instructions that the tone should be divided into three equal parts — a description that leads directly to 19 equal divisions of the octave. This is the earliest known intentional use of 19edo in composed music.
In 1577, Spanish music theorist Francisco de Salinas described 1/3-comma meantone, a tuning in which the fifth is 694.786 cents — only a twentieth of a cent away from 19edo’s fifth of 694.737 cents. He even suggested tuning nineteen notes to the octave, which, since the system nearly closes at that point, is effectively 19edo. In 1835, mathematician Wesley Woolhouse proposed it as a practical alternative to other meantone systems.
What all of this means is that 19edo isn’t some futuristic experiment — it’s a venerable historical tuning that simply lost out to 12edo as instruments and trade standardized. In fact, most Renaissance and Baroque keyboard music was written for some variety of meantone temperament, making 19edo a historically appropriate choice for rendering that repertoire.
Notation: You Already Know It
Here’s the most immediately practical thing about 19edo for musicians: you use standard notation. The same staff, the same letters A through G, the same sharps and flats. No new symbols required.
The crucial difference is how enharmonics work. In 12edo, C# and Db are the same note — they’re “enharmonically equivalent.” In 19edo, they are different notes, about 63 cents apart. The same goes for every other enharmonic pair: D# and Eb are different, G# and Ab are different, and so on.
This is actually how notation was always meant to work. The reason we have both sharps and flats in the first place is that they originally referred to different pitches. In meantone tunings (of which 19edo is one), a sharp raises a note by a small chromatic semitone, while a flat lowers it by a larger diatonic semitone. In 19edo those two semitones have sizes of 1 step and 2 steps respectively.
There are only two enharmonic equivalents in 19edo without resorting to double sharps or flats: E# = Fb and B# = Cb. Everything else splits into two distinct pitches.
The practical upshot: if you’re writing a C major chord, it’s still C–E–G. If you’re writing C minor, it’s still C–Eb–G. Key signatures work the same way. Chord names work the same way. You can transfer your existing music theory knowledge directly — you just need to stay careful about spelling, because C# and Db now mean genuinely different things.
In terms of step sizes, the major scale in 19edo follows the same W-W-H-W-W-W-H pattern you already know, but now a whole step (W) is 3 scale degrees and a half step (H) is 2 scale degrees, rather than 12edo’s 2 and 1.
New Chords: The Supermajor and Subminor
Here’s where 19edo starts to offer genuinely new harmonic territory. Because C# and Db are different notes, intervals that were identical in 12edo are now distinct. This creates chord qualities that simply don’t exist in standard tuning.
In 12edo, there are two basic triad qualities: major and minor (plus diminished and augmented). In 19edo, there are four main ones:
Major (C–E–G): The same major chord you know, with a pure-ish major third. Sounds sweeter and more stable than in 12edo.
Minor (C–Eb–G): Standard minor chord. The minor third is nearly pure — one of 19edo’s best intervals.
Supermajor (C–E#–G): Written as C(#3) or Csmaj. The third is one step wider than a major third — about 442 cents. This approximates the 9/7 ratio, a bright, tense, strangely colorful sound that has no equivalent in 12edo. Think of it as a major chord with a sharp, penetrating quality.
Subminor (C–Ebb–G): Written as C(b3) or Csmin. The third is one step narrower than a minor third — about 253 cents. This approximates the 7/6 ratio, a darker, more hollow sound than a standard minor chord. The Ebb (E double-flat) is a note that doesn’t exist in 12edo.
These aren’t exotic or alien-sounding chords — they have clear emotional characters and sit comfortably alongside regular major and minor chords in progressions. The supermajor has a kind of brilliant, strident brightness; the subminor has a deep, melancholy hollowness. Both are immediately usable.
The same expansion applies to seventh chords. In 19edo you have the standard major seventh, minor seventh, and dominant seventh — but also a harmonic seventh chord (C–E–G–Bbb, sometimes called Ch7), which uses a “diminished seventh” interval that approximates the pure 7/4 ratio. This is the chord you hear in blues and barbershop singing when vocalists naturally drop to a tuning that clashes slightly with a piano — 19edo lets you do it with an instrument tuned to hit that ratio on purpose.
For a more complete breakdown of chords in 19edo, the 19edo chords page on the Xenharmonic Wiki is an excellent reference.
The Pentatonic Scale Gets More Interesting
One of the subtler but very musically relevant properties of 19edo is how it changes the feel of familiar scales.
Because 19edo has narrow whole tones and wide diatonic semitones relative to 12edo, the diatonic scale (the standard major scale) can sound slightly more mellow or “dull” compared to its 12edo counterpart. The half steps are bigger and softer, the whole steps smaller.
The pentatonic scale, however, flips this around. The contrast between the pentatonic scale’s two step sizes — the narrow whole tone and the wide minor third — becomes much more pronounced in 19edo than in 12edo. Many players find 19edo’s pentatonic scale more expressive and emotionally vivid as a result. Where 12edo has an expressive diatonic scale and a relatively bland pentatonic, 19edo has a more mellow diatonic and a more intense, evocative pentatonic.
This suggests a natural compositional approach for 19edo: lean heavily on pentatonic structures, use them as “super-chords” whose modulations define your harmonic motion, and treat the full diatonic scale as a more fluid, ambient space between those pentatonic anchors.
Key Changes and New Harmonic Tricks
Because enharmonic equivalents are genuinely different notes, modulation works differently in 19edo — and opens up new possibilities.
In 12edo, a pivot chord modulation works because a chord can belong to two different keys simultaneously. In 19edo, you can exploit the fact that a chord spelled one way in one key and the “same” chord spelled enharmonically in another key are actually slightly different pitches. This lets you slide between keys in ways that would be impossible in 12edo, creating moments of subtle harmonic surprise.
More concretely: instead of modulating up a semitone (a common pop technique), you can modulate up a diminished third — an interval that doesn’t exist in 12edo but sits between a whole step and a semitone in 19edo. To listeners conditioned by 12edo, this creates a jolt of tension and novelty before the ear settles in.
The 19edo Primer on the Xenharmonic Wiki goes into specific chord progressions and modulation strategies in practical detail, including examples using standard roman numeral notation.
What About Scales Beyond the Diatonic?
19edo contains all the standard modes (Dorian, Phrygian, Lydian, etc.) — they work exactly as you’d expect. But it also supports a rich variety of non-diatonic scales that emerge naturally from the tuning’s structure.
A few worth knowing:
Negri[9]: A 9-note scale with an almost hypnotic evenness. 8 of its 9 steps are the same size (2 steps each), with one slightly wider gap. It’s simple to navigate and has a dreamy, suspended quality.
Sensi[8]: An 8-note scale built from a generator of 7 steps (about 442 cents). It’s been described as 19edo’s answer to the diminished scale — built from two interlocked diminished seventh chords, but with additional harmonic richness from the 7th and 13th harmonics.
Meantone chromatic: The full 12-note chromatic scale of 19edo, which gives you all the standard chromatic possibilities plus the richer interval quality of meantone thirds.
For a comprehensive list of available scales and their modes, see the 19edo modes page.
Playing 19edo: Practical Considerations
Guitar and fretted instruments: A 19edo guitar requires a refret — the frets are placed at different positions to the nineteen-equal divisions rather than twelve. The neck length and playing technique don’t change significantly, especially on longer-scale instruments. If you want to experiment without committing to a refret, there are software-based approaches using pitch-shifting effects or MIDI guitars. The Xenharmonic Wiki guide to tuning a 19edo guitar by ear is a useful practical reference.
Standard guitar with standard tuning: You can approximate 19edo by adjusting the open strings slightly from A=440. If your reference is A=440, the adjustments for standard EADGBE tuning are roughly: E flat 5 cents, A standard, D sharp 5 cents, G sharp 11 cents, B flat 11 cents, E flat 5 cents. This won’t give you 19edo frets, but it brings your open strings into 19edo alignment for playing with others tuned similarly.
Keyboards: Isomorphic keyboards (like the Lumatone or various hexagonal button layouts) are particularly good for 19edo because the same fingering patterns work across all keys. Standard piano keyboards can be used with split sharps — a historical approach that was common on harpsichords. Some DAW-based setups let you remap a standard MIDI controller to play 19edo using pitch-bend tuning tables.
Software and DAWs: Tools like Surge XT, Vital, and most modern software synthesizers support Scala tuning files or MTS (MIDI Tuning Standard), letting you retune to 19edo with minimal effort. The learning curve is mostly on the instrument side — the software side is largely solved.
Serialism in 19edo
If you’re interested in 20th-century compositional techniques, 19-tone serialism works exactly like 12-tone serialism, just with 19 pitch classes instead of 12. A tone row uses each of the 19 notes exactly once before repeating. Bostjan Zupancic’s piece Brain for Breakfast (2016) is a notable example of 19-tone serial composition and is a good listening starting point for this approach.
What to Listen To
The 19edo music page on the Xenharmonic Wiki has an enormous catalog spanning the 16th century to 2026, including:
Historical: Costeley’s Seigneur Dieu ta pitié (1558), rendered by Roger Wibberley — the oldest known piece specifically composed for 19edo.
Classical in 19edo: Numerous Bach pieces rendered in 19edo by Claudi Meneghin and Fabio Costa, including Well-Tempered Clavier preludes and fugues, which take on a noticeably sweeter, more consonant character in this tuning.
Original 20th-century works: Easley Blackwood’s Fanfare in 19-note Equal Tuning (1980) is a landmark piece by a rigorous American composer exploring equal temperaments systematically.
Contemporary: Artists like Sevish, Xotla, Francium, and many others have released full albums in 19edo across genres from jazz to electronic to classical, available on Bandcamp and Spotify.
Is 19edo Right for You?
19edo is probably the easiest entry point into microtonality for a trained musician because so much of what you already know transfers directly. The notation is familiar, the harmonic logic is recognizable, the scales you know still exist and work, and the improvements to thirds and sixths are immediately audible and pleasing rather than jarring.
The main thing to adjust mentally is letting go of enharmonic equivalence. C# and Db being different is initially confusing, but it quickly starts to feel natural — and eventually you’ll wonder how 12edo got away with collapsing them together for so long.
If you want to go deeper, the Xenharmonic Wiki’s 19edo page is the most comprehensive single resource available, covering theory, notation, scales, chords, instruments, and a vast music catalog. The Primer for 19edo is the best place to start if you want a structured walkthrough.
The world of 19edo is large enough that you could spend a musical lifetime in it and still find new territory. But it’s also approachable enough that you can start making music in it this week — with instruments you already own and theory you already understand.
Further reading: 19edo on the Xenharmonic Wiki · 19edo chords · 19edo modes · Primer for 19edo · How to tune a 19edo guitar by ear
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