28/15
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| Ratio | 28/15 |
| Factorization | 22 × 3-1 × 5-1 × 7 |
| Monzo | [2 -1 -1 1⟩ |
| Size in cents | 1080.5572¢ |
| Name | septimal grave major seventh |
| Color name | zg8, zogu octave |
| FJS name | [math]\text{d8}^{7}_{5}[/math] |
| Special properties | reduced |
| Tenney height (log2 nd) | 8.71425 |
| Weil height (log2 max(n, d)) | 9.61471 |
| Wilson height (sopfr(nd)) | 19 |
| Harmonic entropy (Shannon, [math]\sqrt{nd}[/math]) |
~4.22382 bits |
[sound info] | |
| open this interval in xen-calc | |
28/15 is a 7-limit just intonation interval of about 1080.6 cents. It is well approximated by 10edo (9\10).
Terminology
Despite being approximated by the major seventh in systems like septimal meantone, and even being called the septimal grave major seventh by some musicians, 28/15 is a diminished octave in just intonation notation systems such as Sagittal notation, Helmholtz-Ellis notation and the Functional Just System, viewed as the Pythagorean diminished octave (4096/2187) altered by 5120/5103.