25/24: Difference between revisions

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-"chroma"; +"dicot comma". Chroma is ever more general than this interval. 17edo -> 7edo since the latter is more typical
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{{Infobox Interval
{{Infobox Interval
| Name = just chromatic semitone, classic(al) chromatic semitone, diptolemaic chromatic semitone, chroma
| Name = just chromatic semitone, classic(al) chromatic semitone, diptolemaic chromatic semitone, dicot comma
| Color name = yy1, yoyo unison
| Color name = yy1, yoyo unison
| Sound = jid_25_24_pluck_adu_dr220.mp3
| Sound = jid_25_24_pluck_adu_dr220.mp3
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}}
}}


'''25/24''', the '''just chromatic semitone''', '''classic(al) chromatic semitone''' or '''diptolemaic chromatic semitone''' (short: '''chroma'''), 70.672{{cent}}, is the [[superparticular]] ratio which marks the difference between the [[5-limit]] seconds, [[16/15]] and [[10/9]], [[27/25]] and [[9/8]], thirds, [[6/5]] and [[5/4]], sixths, [[8/5]] and [[5/3]], and sevenths, [[16/9]] and [[50/27]], and [[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.
'''25/24''', the '''just chromatic semitone''', '''classic(al) chromatic semitone''' or '''diptolemaic chromatic semitone''', 70.672{{cent}}, is the [[superparticular]] ratio which marks the difference between the [[5-limit]] seconds, [[16/15]] and [[10/9]], [[27/25]] and [[9/8]], thirds, [[6/5]] and [[5/4]], sixths, [[8/5]] and [[5/3]], and sevenths, [[16/9]] and [[50/27]], and [[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.


== Approximation ==
== Approximation ==
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== Temperaments ==
== Temperaments ==
If 25/24 is treated as a comma to be tempered out, you remove the distinction between major and minor thirds and get only a single neutral interval in their place as in [[dicot family]], and edos like [[10edo]] or 17edo.
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 major and minor thirds are removed and get only a single neutral interval in their place, as in [[7edo]] and [[10edo]]. See [[dicot family]] for the rank-2 family where it is tempered out.  


==See also==
== See also ==
* [[36/25]] – its [[fifth complement]]
* [[36/25]] – its [[fifth complement]]
* [[48/25]] – its [[octave complement]]
* [[48/25]] – its [[octave complement]]
* [[Dicot family]], where it is tempered out
* [[Gallery of just intervals]]
* [[Gallery of just intervals]]
* [[Medium comma]]
* [[Medium comma]]
* [[List of superparticular intervals]]
* [[List of superparticular intervals]]
* [[Chroma]] – a generalising concept for [[MOS]] scales
* [[Chromatic semitone]] – a generalising concept for the [[diatonic]] scale
* [[2187/2048]] – the Pythagorean chromatic semitone
* [[Chroma]] – a generalising concept for all [[mos]] scales
* [[Sqrt(25/24)]] – its exact half
* [[Sqrt(25/24)]] – its exact half



Revision as of 15:29, 26 January 2023

Interval information
Ratio 25/24
Factorization 2-3 × 3-1 × 52
Monzo [-3 -1 2
Size in cents 70.67243¢
Names just chromatic semitone,
classic(al) chromatic semitone,
diptolemaic chromatic semitone,
dicot comma
Color name yy1, yoyo unison
FJS name [math]\displaystyle{ \text{A1}^{5,5} }[/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
Comma size medium
S-expression S5

[sound info]
Open this interval in xen-calc

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, 27/25 and 9/8, thirds, 6/5 and 5/4, sixths, 8/5 and 5/3, and sevenths, 16/9 and 50/27, and 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.

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 major and minor thirds are removed and get only a single neutral interval in their place, as in 7edo and 10edo. See dicot family for the rank-2 family where it is tempered out.

See also