25/24

Interval information

Ratio	25/24
Factorization	2-3 × 3-1 × 52
Monzo	[-3 -1 2⟩
Size in cents	70.67243¢
Names	classic chromatic semitone, chroma
FJS name	[math]\displaystyle{ \text{A1}^{25} }[/math]
Special properties	square superparticular, reduced
Tenney norm (log2 nd)	9.22882
Weil norm (log2 max(n, d))	9.28771
Wilson norm (sopfr(nd))	19
[sound info]
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The classic chromatic semitone (short: chroma), 25/24, 70.672 cents, is the superparticular ratio which marks the difference between the 5-limit thirds, 6/5 and 5/4, and sixths, 8/5 and 5/3. It is therefore the amount which sharpens or flattens a 5-limit third or sixth, 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. If it is treated as a comma to be tempered out, you remove the distinction between major & minor thirds and get only a single neutral interval in their place as in dicot family, and edos like 10edo or 17edo.

It is very accurately approximated by 34edo (2\34).

See also

• 36/25 – its fifth complement
• 48/25 – its octave complement
• Dicot family, which tempers it out
• Gallery of just intervals
• Medium comma
• List of superparticular intervals
• Chroma – a generalising concept for MOS scales
• Pythagorean chromatic semitone