28/27: Difference between revisions

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m Mention of enneadecal
It need to be pointed out the names differ by contexts (and "septimal third-tone" sounds most neutral so I place it first)
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| Monzo = 2 -3 0 1
| Monzo = 2 -3 0 1
| Cents = 62.9609
| Cents = 62.9609
| Name = small septimal chroma, <br>septimal third-tone, <br>subminor second, <br>septimal minor second
| Name = septimal third-tone, <br>small septimal chroma, <br>subminor second, <br>septimal minor second, <br>trienstonic comma
| Color name = z2, zo 2nd
| Color name = z2, zo 2nd
| FJS name = m2<sup>7</sup>
| FJS name = m2<sup>7</sup>
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}}
}}


The [[superparticular]] interval '''28/27''' (also '''small septimal chroma''' or '''septimal third-tone''') has the seventh triangular number as a numerator and is the difference between [[15/14]] and [[10/9]], [[9/8]] and [[7/6]], [[9/7]] and [[4/3]], [[3/2]] and [[14/9]], [[12/7]] and [[16/9]], and [[9/5]] and [[28/15]].  
The [[superparticular]] interval '''28/27''', '''septimal third-tone''' or '''small septimal chroma''' has the seventh triangular number as a numerator and is the difference between [[15/14]] and [[10/9]], [[9/8]] and [[7/6]], [[9/7]] and [[4/3]], [[3/2]] and [[14/9]], [[12/7]] and [[16/9]], and [[9/5]] and [[28/15]].  


Although called a ''chroma'' for its proximity (and conflation in systems like [[septimal meantone]]) with the classic chroma [[25/24]], 28/27 is a ''diatonic semitone'' in both [[Helmholtz-Ellis notation]] and [[Functional Just System]] because it is [[64/63]] smaller than the Pythagorean minor second [[256/243]]. Hence, it may be described as the '''septimal minor second''' or '''subminor second''' if treated as an interval in its own right. This is analogous to the septimal major second [[8/7]], which has the same relationship with [[9/8]], and such classification suggests the function of a strong leading tone added to the traditional harmony.  
Although called a ''chroma'' for its proximity (and conflation in systems like [[septimal meantone]]) with the classic chroma [[25/24]], 28/27 is a ''diatonic semitone'' in both [[Helmholtz-Ellis notation]] and [[Functional Just System]] because it is [[64/63]] smaller than the Pythagorean minor second [[256/243]]. Hence, it may be described as the '''septimal minor second''' or '''subminor second''' if treated as an interval in its own right. This is analogous to the septimal major second [[8/7]], which has the same relationship with [[9/8]], and such classification suggests the function of a strong leading tone added to the traditional harmony.  


It is very accurately approximated by [[19edo]] (1\19), and hence the [[enneadecal]] temperament.  
It is very accurately approximated by [[19edo]] (1\19), and hence the [[enneadecal]] temperament.  
On the other side of things, it may be called the '''trienstonic comma''' if treated as a [[comma]] to be tempered out, and in fact the [[trienstonic clan]] does exactly that.


== See also ==
== See also ==
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[[Category:Third tone]]
[[Category:Third tone]]
[[Category:Chroma]]
[[Category:Chroma]]
[[Category:Medium comma]]
[[Category:Trienstonic]]

Revision as of 15:47, 9 January 2021

Interval information
Ratio 28/27
Factorization 22 × 3-3 × 7
Monzo [2 -3 0 1
Size in cents 62.9609¢
Names septimal third-tone,
small septimal chroma,
subminor second,
septimal minor second,
trienstonic comma
Color name z2, zo 2nd
FJS name [math]\displaystyle{ \text{m2}^{7} }[/math]
Special properties superparticular,
reduced
Tenney norm (log2 nd) 9.56224
Weil norm (log2 max(n, d)) 9.61471
Wilson norm (sopfr(nd)) 20

[sound info]
Open this interval in xen-calc

The superparticular interval 28/27, septimal third-tone or small septimal chroma has the seventh triangular number as a numerator and is the difference between 15/14 and 10/9, 9/8 and 7/6, 9/7 and 4/3, 3/2 and 14/9, 12/7 and 16/9, and 9/5 and 28/15.

Although called a chroma for its proximity (and conflation in systems like septimal meantone) with the classic chroma 25/24, 28/27 is a diatonic semitone in both Helmholtz-Ellis notation and Functional Just System because it is 64/63 smaller than the Pythagorean minor second 256/243. Hence, it may be described as the septimal minor second or subminor second if treated as an interval in its own right. This is analogous to the septimal major second 8/7, which has the same relationship with 9/8, and such classification suggests the function of a strong leading tone added to the traditional harmony.

It is very accurately approximated by 19edo (1\19), and hence the enneadecal temperament.

On the other side of things, it may be called the trienstonic comma if treated as a comma to be tempered out, and in fact the trienstonic clan does exactly that.

See also