Xenharmonic Wiki

21/20

Revision as of 09:34, 15 October 2020 by FloraC (talk | contribs) (Clarification and maybe we avoid the term "chromatic semitone" here, just chroma)
Interval information
Ratio 21/20
Factorization 2-2 × 3 × 5-1 × 7
Monzo [-2 1 -1 1⟩
Size in cents 84.46719¢
Names minor semitone,
large septimal chroma
Color name zg2, zogu 2nd
FJS name [math]\displaystyle{ \text{m2}^{7}_{5} }[/math]
Special properties superparticular,
reduced
Tenney height (log2 nd) 8.71425
Weil height (log2 max(n, d)) 8.78463
Wilson height (sopfr(nd)) 19

[sound info]
Open this interval in xen-calc

21/20 is a small semitone of about 85 cents. It may be found in 7-limit just intonation as, for example, the difference between 8/7 and 6/5, or between 5/3 and 7/4.

Although called a chroma for its proximity (and conflation in systems like septimal meantone) with the major chroma 135/128, 21/20 is a diatonic semitone in both Helmholtz-Ellis notation and Functional Just System because it is 5120/5103 smaller than the Pythagorean minor second 256/243.

See also

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