25/24: Difference between revisions

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{{Infobox Interval
{{Infobox Interval
| Icon =
| Name = just chromatic semitone, classic(al) chromatic semitone, diptolemaic chromatic semitone, dicot comma
| Ratio = 25/24
| Color name = yy1, yoyo unison
| Monzo = -3 -1 2
| Cents = 70.67243
| Name = classic chromatic semitone, <br>chroma
| Color name =  
| FJS name = A1<sup>25</sup>
| Sound = jid_25_24_pluck_adu_dr220.mp3
| Sound = jid_25_24_pluck_adu_dr220.mp3
| Comma = yes
}}
}}
'''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]], 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.


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]].  
== Approximation ==
25/24 is very accurately approximated by [[17edo]]'s 1\17 (70.588{{cent}}). In fact, the interval that results from stacking seventeen 25/24 chromatic semitones reduced by an octave is the [[septendecima]], only 1.428{{cent}} in size.


It is very accurately approximated by 17edo's 1\17 (70.588¢). In fact, a chain of seventeen 25/24 chromatic semitones is only 1.428¢ flat of the octave.
== 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 ==
== See also ==
* [[36/25]] – its [[fifth complement]]
* [[36/25]] – its [[fifth complement]]
* [[48/25]] – its [[octave complement]]
* [[48/25]] – its [[octave complement]]
* [[Dicot family]], which tempers it out
* [[Sqrt(25/24)]] – its exact half
* [[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 [[5L 2s|diatonic]] scale
* [[2187/2048|Pythagorean chromatic semitone]]
* [[Chroma]] – a generalising concept for all [[mos]] scales


[[Category:5-limit]]
[[Category:Chroma]]
[[Category:Chroma]]
[[Category:Interval ratio]]
[[Category:Semitone]]
[[Category:Semitone]]
[[Category:Third tone]]
[[Category:Third tone]]
[[Category:Listen]]
[[Category:Dicot]]
[[Category:Superparticular]]
[[Category:Commas named for how they divide the fifth]]