6:7:9: Difference between revisions

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'''6:7:9''', the ''subminor triad'' or ''septimal minor triad'', is a triad in the [[7-limit]] sometimes used in place of a [[minor triad]]. It appears as a minor triad in the [[5L 2s|diatonic scale]] of [[superpyth]], as [[64/63]] being tempered out means [[32/27]] is equated with [[7/6]]. This is in contrast to [[meantone]], where 32/27 is equated with [[6/5]], and thus the minor triad becomes [[10:12:15]].
'''6:7:9''', the ''subminor triad'' or ''septimal minor triad'', is a triad in the [[7-limit]] sometimes used in place of a [[minor triad]]. It appears as a minor triad in the [[5L 2s|diatonic scale]] of [[superpyth]], as [[64/63]] being tempered out means [[32/27]] is equated with [[7/6]]. This is in contrast to [[meantone]], where 32/27 is equated with [[6/5]], and thus the minor triad becomes [[10:12:15]].


6:7:9 is the second-simplest [[otonal]] {{w|tertian harmony|tertian}} triad, past [[4:5:6]], and is thus very [[consonant]]. However, its inverse, [[14:18:21]], may sound less stable due to its higher otonal complexity. In addition, the [[7/6]] and [[9/7]] intervals differ by [[54/49]], an interval of 168 [[cent]]s, which means the subminor and supermajor triads don't contrast very well the same way 5-limit triads do. Nonetheless, these triads may be used in progressions together with the 5-limit ones.
6:7:9 is the second-simplest [[otonal]] {{w|tertian harmony|tertian}} triad, past [[4:5:6]], and is thus very [[consonant]]. The inverse of 6:7:9 is [[14:18:21]], the supermajor triad. These triads can be used in the same way as the 5-limit ones, leading to a septimal version of tertian harmony. However, this has a number of issues. First of all, [[14:18:21]] may sound unstable due to its relatively high otonal complexity. In addition, the [[7/6]] and [[9/7]] intervals differ by [[54/49]], an interval of 168 [[cent]]s, unlike [[5/4]] and [[6/5]], which differ by [[25/24]], an interval only about 71 cents in size. This means the 6:7:9 and 14:18:21 chords don't contrast as well as the 5-limit 4:5:6 and 10:12:15 chords. Another important fact is that the 6:7:9 chord doesn't contain the root, though it is a subchord of [[4:5:6:7:9]] which does. These triads are nonetheless useful in tertian harmony, bringing new flavors not found in the 5-limit.


== See also ==
== See also ==
* [[14:18:21]] - the supermajor triad
* [[14:18:21]] - the supermajor triad
* [[6:7:8:9]] - adds [[4/3]]
* [[6:7:9:10]] - adds [[5/3]]
* [[6:7:9:10]] - adds [[5/3]]


{{Todo|expand|improve readability|research|inline=1|text=This chord may be closely connected to 7-limit interpretations of the Blues scale.}}
{{Todo|add sound example|research|inline=1|text=This chord may be closely connected to 7-limit interpretations of the Blues scale.}}


[[Category:Minor triads|#]] <!-- 1-digit first number -->
[[Category:Minor triads|#]] <!-- 1-digit first number -->

Revision as of 09:51, 22 December 2025

Chord information
Harmonics 6:7:9
Subharmonics 1/(21:18:14)
Intervals from root 1/17/63/2
Cents from root 267¢702¢
Step intervals 7/6, 9/7
Step cents 267¢, 435¢
Color name zo or z
Prime limit 7
Genus 327 (63)
Intervallic odd limit 9
Otonal odd limit 9
Utonal odd limit 21
Consistent edos (d ≥ 2) 5edo*, 14edo*, 17edo*, 19edo*, …

6:7:9, the subminor triad or septimal minor triad, is a triad in the 7-limit sometimes used in place of a minor triad. It appears as a minor triad in the diatonic scale of superpyth, as 64/63 being tempered out means 32/27 is equated with 7/6. This is in contrast to meantone, where 32/27 is equated with 6/5, and thus the minor triad becomes 10:12:15.

6:7:9 is the second-simplest otonal tertian triad, past 4:5:6, and is thus very consonant. The inverse of 6:7:9 is 14:18:21, the supermajor triad. These triads can be used in the same way as the 5-limit ones, leading to a septimal version of tertian harmony. However, this has a number of issues. First of all, 14:18:21 may sound unstable due to its relatively high otonal complexity. In addition, the 7/6 and 9/7 intervals differ by 54/49, an interval of 168 cents, unlike 5/4 and 6/5, which differ by 25/24, an interval only about 71 cents in size. This means the 6:7:9 and 14:18:21 chords don't contrast as well as the 5-limit 4:5:6 and 10:12:15 chords. Another important fact is that the 6:7:9 chord doesn't contain the root, though it is a subchord of 4:5:6:7:9 which does. These triads are nonetheless useful in tertian harmony, bringing new flavors not found in the 5-limit.

See also

Todo: add sound example, research

This chord may be closely connected to 7-limit interpretations of the Blues scale.