13-limit
The 13-limit (a.k.a. yazalatha in color notation) consists of just intonation intervals such that the highest prime factor in all ratios is 13. It is the 6th prime limit and is a superset of the 11-limit and a subset of the 17-limit. An example of an interval in the 13-limit is 40/39, since 40 is 2 × 2 × 2 × 5 and 39 is 3 × 13; a counterexample is 34/33, since 34 is 2 × 17, and 17 is a prime number higher than 13.
The 13-limit is a rank-6 system, and can be modeled in a 5-dimensional lattice, with the primes 3, 5, 7, 11, and 13 represented by each dimension. The prime 2 does not appear in the typical 13-limit lattice because octave equivalence is presumed. If octave equivalence is not presumed, a sixth dimension is needed.
These things are contained by the 13-limit, but not the 11-limit:
- The 13- and 15-odd-limit;
- Mode 7 and 8 of the harmonic or subharmonic series; this means it completes the 4th octave of those series.
In a 13-limit system, all the ratios of the 13- or 15-odd-limit can be treated as potential consonances.
The 13-limit intervals of the 2.3.13 subgroup, such as 13/12 and 16/13, are close to neutral intervals, but are further from true (hemipythagorean) neutral intervals than 2.3.11 subgroup intervals, and thus may be termed "subneutral" and "superneutral". Such intervals can be obtained by translating a Pythagorean interval by the tridecimal quartertone of 1053/1024.
As prime limits increase, ratios containing different primes over 3 in the numerator and denominator become more and more numerous. Such ratios include 15/14, 14/13, 11/10, 15/13, 13/11, 14/11, 13/10, 15/11, 7/5, and their octave complements. An example of a way to use these intervals is to build tertian triads such as 10:13:15, which consists of a 13/10 ultramajor third and a 15/13 inframinor third. Other examples include the neogothic major and minor triads of 22:28:33 and 22:26:33, which can be tempered to the 13-odd-limit via vanishing of 364/363, but can also be used as they are.
The subgroup can be convenient rank-reduced into the 7-limit without much loss in accuracy by tempering out 2080/2079 and 4096/4095, resulting in the olympic temperament, which equates 36/35 with 1053/1024 and (64/63)2 with 33/32. Other notable rank-reductions include orthoschismic and cassaschismic, which rank-reduces olympic by equating 81/80 or 64/63 respectively with the Pythagorean comma.
Edo approximation
Edos which represent 13-limit intervals better (monotonicity limit ≥ 13 and decreasing TE error): 15, 17c, 19, 26, 27e, 29, 31, 41, 46, 53, 58, 72, 87, 103, 111, 121, 130, 183, 190, 198, 224, 270, 494 and so on. For a more comprehensive list, see Sequence of equal temperaments by error.
Here is a list of edos which tunes the 13-limit well relative to their size (TE relative error < 5.5%): 31, 41, 46, 53, 58, 72, 87, 94, 103, 111, 121, 130, 140, 152f, 159, 183, 190, 198, 212, 217, 224, 270, 282, 296, 301, 311, 320, 328, 342f, 354, 364, 369f, 373, 383, 400, 414, 422, 431, 441, 460, 472, 494, and so on.
| Note: | Wart notation is used to specify the val chosen for the edo. In the above list, "27e" means taking the second closest approximation of harmonic 11. |
Intervals
Here are all the 15-odd-limit intervals of 13:
| Ratio | Cents value | Color name | Name | |
|---|---|---|---|---|
| 14/13 | 128.298 | 3uz2 | thuzo 2nd | tridecimal supraminor second |
| 13/12 | 138.573 | 3o2 | tho 2nd | tridecimal subneutral second |
| 15/13 | 247.741 | 3uy2 | thuyo 2nd | tridecimal semifourth |
| 13/11 | 289.210 | 3o1u3 | tholu 3rd | tridecimal minor third |
| 16/13 | 359.472 | 3u3 | thu 3rd | tridecimal supraneutral third |
| 13/10 | 454.214 | 3og4 | thogu 4th | tridecimal naiadic |
| 18/13 | 563.382 | 3u4 | thu 4th | tridecimal sub-tritone |
| 13/9 | 636.618 | 3o5 | tho 5th | tridecimal super-tritone |
| 20/13 | 745.786 | 3uy5 | thuyo 5th | tridecimal cocytic |
| 13/8 | 840.528 | 3o6 | tho 6th | tridecimal subneutral sixth |
| 22/13 | 910.790 | 3u1o6 | thulo 6th | tridecimal major sixth |
| 26/15 | 952.259 | 3og7 | thogu 7th | tridecimal semitwelfth |
| 24/13 | 1061.427 | 3u7 | thu 7th | tridecimal supraneutral seventh |
| 13/7 | 1071.702 | 3or7 | thoru 7th | tridecimal submajor seventh |
Music
- Justification (2022)
- Bicycle Wheels (2023)
- Venusian Cataclysms[dead link] play[dead link]
- Chord Progression on the Harmonic Overtone Series[dead link] play[dead link]
- String Quartet No. 5 (1979) – Bandcamp | YouTube – performed by Kepler Quartet
- String Quartet No. 7 (1984)
- performed by Kepler Quartet
- Unlicensed Copy (2017) – mostly 7-limit with some erstwhile 13-based chromaticisms
- WIP cover of Sheik's Theme by Koji Kondo (2025; original was 1996) - tuning adapted from Ibn Sina
- Canon on a ground – in 2.11.13 subgroup
- P`rismatic fut`URE (2025)
- fretless harp guitar study (2026)
- Threnody for the Victims of Wolfgang Amadeus Mozart (archived 2010) – 13-limit JI in 6079edo tuning
- Rough Diamond (archived 2010) a.k.a. Diamond in the Rough[1] – symphonic con brio using the Partch 13-odd-limit tonality diamond as a scale.
- Dying Visions of a Lonesome Machine (2021)
- Avenoir (2022)
- I Was a Teenage Boltzmann Brain (2022)
- Atlas Apassionata (2022)
See also
- Gallery of just intervals
- Tridecimal neutral seventh chord
- Augmented chords in just intonation, some (they are 13-limit)