25/24
| Interval information |
classic(al) chromatic semitone,
diptolemaic chromatic semitone,
dicot comma
reduced
(Shannon, [math]\displaystyle{ \sqrt{nd} }[/math])
[sound info]
25/24, the just chromatic semitone, classic(al) chromatic semitone or diptolemaic chromatic semitone, 70.672 ¢, is the superparticular ratio which marks the difference between the 5-limit seconds, 16/15 and 10/9, thirds, 6/5 and 5/4, sixths, 8/5 and 5/3, and sevenths, 9/5 and 15/8. It is therefore the amount which sharpens or flattens a 5-limit second, third, sixth, or seventh, and when notating 5-limit just intonation it can be associated with the sharp or flat symbol, and along with an additional symbol for the 81/80 comma, it can be used for a complete system of 5-limit notation as an extension of diatonic.
Approximation
25/24 is very accurately approximated by 17edo's 1\17 (70.588 ¢). In fact, the interval that results from stacking seventeen 25/24 chromatic semitones reduced by an octave is the septendecima, only 1.428 ¢ in size.
Temperaments
If 25/24 is treated as a comma to be tempered out, it may be called the dicot comma. Doing so leads to the dicot temperament, where the distinction between 5-limit major and minor thirds are removed and there is only a single neutral interval functioning as both, as in 7edo, 10edo, and 17edo. See dicot family for the rank-2 family where it is tempered out.
See also
- 36/25 – its fifth complement
- 48/25 – its octave complement
- Sqrt(25/24) – its exact half
- 1ed25/24 - its equal multiplication
- Gallery of just intervals
- Medium comma
- List of superparticular intervals
- Chromatic semitone – a generalising concept for the diatonic scale
- Chroma – a generalising concept for all mos scales