7/5: Difference between revisions
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{{Infobox Interval | {{Infobox Interval | ||
| Name = narrow tritone, lesser septimal tritone, Huygens' tritone | |||
| Name = narrow tritone, | |||
| Color name = zg5, zogu 5th | | Color name = zg5, zogu 5th | ||
| Sound = jid_7_5_pluck_adu_dr220.mp3 | | Sound = jid_7_5_pluck_adu_dr220.mp3 | ||
}} | }} | ||
{{Wikipedia|Septimal tritone}} | |||
In [[7-limit]] [[ | In [[7-limit]] [[just intonation]], '''7/5''' is a '''narrow [[tritone]]''' (or '''Huygens' tritone''') measuring about 582.5¢. It is a noticeable 17.5¢ away from the 600¢ half-octave (square root of 2) tritone of [[12edo]] and every even-numbered [[edo]]. It represents the difference between [[7/4]] and [[5/4]]. | ||
While in the context of the [[harmonic seventh chord]], it is rightly recognized as a type of diminished fifth, it can also be argued on the basis of the fact that 7/5 interval is smaller than 600 cents that it acts more as a type of augmented fourth than a diminished fifth – an analysis that is required in cases where this interval occurs in a [[5L 2s|diatonic scale]] that demonstrates [[Rothenberg propriety]]. This is one of the reasons why 7/4 can be argued to be a type of "sinth" – a cross between a sixth and a seventh – as opposed to merely a subminor seventh. | |||
7/5 is notable for its low [[harmonic entropy]], and is often reported to sound more consonant than the half-octave tritone; indeed it appears in the harmonic seventh chord that forms the basis of consonance in 7-limit JI. Its inversion is [[10/7]], which measures about 617.5¢, and these two septimal tritones differ by the [[superparticular]] interval [[50/49]], about 35.0¢. Systems which temper out 50/49 will equate 7/5 and [[10/7]], usually to the 600¢ half-octave. | |||
Another just tritone is [[729/512]] (611.7¢), and this is literally a tri-tone, since it is (9/8)<sup>3</sup>, or three "whole tones". Yet another is [[45/32]], about 590.2¢, which appears in the [[5-limit]] (inversion is [[64/45]]). See also [[13/9]], [[18/13]], [[17/12]], [[24/17]], [[25/18]] and [[36/25]]. | |||
== Approximation == | |||
{{Interval edo approximation|7/5}} | |||
== See also == | == See also == | ||
* [[10/7]] – its [[octave complement]] | * [[10/7]] – its [[octave complement]] | ||
* [[15/14]] – its [[fifth complement]] | * [[15/14]] – its [[fifth complement]] | ||
* [[Gallery of | * [[Gallery of just intervals]] | ||
[[Category:Tritone]] | [[Category:Tritone]] | ||
[[Category:Over-5]] | [[Category:Over-5 intervals]] | ||
[[Category:Taxicab-2 intervals]] | |||