15/14: Difference between revisions

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Theory: as relationship between thirds
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- misinformation (dyads are neither otonal nor utonal). - duplicate information. Re-organize
 
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{{Wikipedia|Septimal diatonic semitone}}
{{Wikipedia|Septimal diatonic semitone}}
'''15/14''' is a [[superparticular]] ratio with a numerator which is the fifth [[triangular number]]. Because it contains exactly one of each prime up to 7, it appears as the interval between many simple [[7-limit]] ratios, including:
'''15/14''' is a [[superparticular]] ratio with a numerator which is the fifth [[triangular number]]. It is traditionally called a ''diatonic semitone'', perhaps for its proximity (and conflation in systems such as septimal [[meantone]] and [[marvel]]) with the classic diatonic semitone [[16/15]]. However, 15/14 is a ''[[chromatic semitone]]'' in both [[Helmholtz–Ellis notation]] and the [[Functional Just System]], viewed as the apotome [[2187/2048]] altered by [[5120/5103]]. [[Marc Sabat]] has taken to call it the ''major chromatic semitone'' in the same material where [[21/20]] is also named as the minor diatonic semitone<ref>Marc Sabat. [https://masa.plainsound.org/pdfs/crystal-growth.pdf ''Three Crystal Growth Algorithms in 23-limit constrained Harmonic Space'']. Plainsound Music Edition, 2008.</ref>.
 
Because it contains exactly one of each prime up to 7, it appears as the interval between many simple [[7-limit]] ratios. In particular, it is the difference between certain [[interval qualities]] of seconds, thirds, sixths, and sevenths: between classical minor and supermajor, and between subminor and classical major. These are the pairs of intervals separated by 15/14:
* [[28/27]] and [[10/9]]
* [[16/15]] and [[8/7]]
* [[16/15]] and [[8/7]]
* [[7/6]] and [[5/4]]
* [[7/6]] and [[5/4]]
* [[6/5]] and [[9/7]]
* [[6/5]] and [[9/7]]
* [[4/3]] and [[10/7]]
* [[7/5]] and [[3/2]]
* [[14/9]] and [[5/3]]
* [[14/9]] and [[5/3]]
* [[8/5]] and [[12/7]]
* [[8/5]] and [[12/7]]
* [[7/4]] and [[15/8]]
* [[7/4]] and [[15/8]]
* [[9/5]] and [[27/14]]
In addition, it separates the perfect fourth from the larger septimal tritone, and the perfect fifth from the smaller septimal tritone:
* [[4/3]] and [[10/7]]
* [[7/5]] and [[3/2]]


It also arises in higher limits as:  
It also arises in higher limits as:  
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* [[22/15]] and [[11/7]]
* [[22/15]] and [[11/7]]
* [[26/15]] and [[13/7]]
* [[26/15]] and [[13/7]]
== Theory ==
15/14 is traditionally called a ''diatonic semitone'', perhaps for its proximity (and conflation in systems such as septimal [[meantone]] and [[marvel]]) with the classic diatonic semitone [[16/15]]. However, 15/14 is a ''[[Wikipedia:chromatic semitone|chromatic semitone]]'' in both [[Helmholtz–Ellis notation]] and the [[Functional Just System]], viewed as the apotome [[2187/2048]] altered by [[5120/5103]]. [[Marc Sabat]] has taken to call it the ''major chromatic semitone'' in the same material where [[21/20]] is also named as the minor diatonic semitone<ref>Marc Sabat. [https://masa.plainsound.org/pdfs/crystal-growth.pdf ''Three Crystal Growth Algorithms in 23-limit constrained Harmonic Space'']. Plainsound Music Edition, 2008.</ref>.
15/14 is the difference between certain [[interval qualities]] of thirds and sixths: between (classic) minor and supermajor, and between subminor and (classic) major. These are the pairs of intervals separated by 15/14:
* 7/6 and 5/4 (otonal thirds)
* 6/5 and 9/7 (utonal thirds)
* 14/9 and 5/3 (otonal sixths)
* 8/5 and 12/7 (utonal sixths)
[[36/35]] separates the otonal pairs from the utonal pairs; 4/3 separates the thirds from the sixths.
They can also be organized into pairs of intervals differing by 36/35:
* 7/6 and 6/5 (minor thirds)
* 5/4 and 9/7 (major thirds)
* 14/9 and 8/5 (minor sixths)
* 5/3 and 12/7 (major sixths)
15/14 separates the minor pairs from the major pairs; 4/3 separates the thirds from the sixths.
36/35 separates 15/14 from [[25/24]] on one side and [[54/49]] on the other.


== Approximation ==
== Approximation ==
15/14 is very accurately approximated by [[10edo]] (1\10) and all [[linus]] temperaments. The [[linus comma]], 5., is the amount by which a stack of ten 15/14's falls short of the octave.
15/14 is very accurately approximated by [[10edo]] (1\10) and all [[linus]] temperaments. The [[linus comma]], 5.6{{c}}, is the amount by which a stack of ten 15/14's falls short of the octave.


In combination with [[19/17]] it forms a good approximation of [[golden meantone]]. The untempered combination of five 19/17's and two 15/14's leads to an interval that is sharp to an octave by the [[mercurial comma]]: (19/17)<sup>5</sup> × (15/14)<sup>2</sup> = 2 / (mercurial comma).
In combination with [[19/17]] it forms a good approximation of [[golden meantone]]. The untempered combination of five 19/17's and two 15/14's leads to an interval that is sharp to an octave by the [[mercurial comma]]: (19/17)<sup>5</sup> × (15/14)<sup>2</sup> = 2 / (mercurial comma).
{{Interval edo approximation|max_edo=131|15/14}}
 
{{Interval edo approximation|max edo=131|15/14}}


== Temperaments ==
== Temperaments ==