256/243: Difference between revisions
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{{Infobox Interval | {{Infobox Interval | ||
| Name = Pythagorean limma, Pythagorean diatonic semitone, blackwood comma | | Name = Pythagorean limma, Pythagorean diatonic semitone, blackwood comma | ||
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{{Wikipedia| Semitone #Pythagorean tuning }} | {{Wikipedia| Semitone #Pythagorean tuning }} | ||
'''256/243''', the '''Pythagorean limma''' or '''Pythagorean diatonic semitone''', is the [[diatonic semitone]] in [[Pythagorean tuning]]. In other words, it is the [[3-limit]] minor second. It factors as 2<sup>8</sup>/3<sup>5</sup>, and is about 90.2 [[cent]]s in size. It can be generated by stacking five [[4/3]] just perfect fourths and [[octave reduction|octave-reducing]] the resulting interval, or equivalently by decreasing 4/3 by two [[9/8]] major seconds. Unlike the situation in [[meantone]] tunings, it is smaller, not larger, than the corresponding [[chromatic semitone]], which is the Pythagorean augmented unison of [[2187/2048]]. | |||
== Approximation == | == Approximation == | ||
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== Temperaments == | == Temperaments == | ||
When this ratio is taken as a comma to be tempered in the [[5-limit]], it produces the [[blackwood]] temperament, and it may be called the '''blackwood comma'''. Edos tempering it out include [[5edo]], [[10edo]], [[15edo]], [[20edo]], [[25edo]] and [[30edo]]. See [[ | When this ratio is taken as a comma to be tempered in the [[5-limit]], it produces the [[blackwood]] temperament, and it may be called the '''blackwood comma''', named after [[Easley Blackwood Jr]]. Edos tempering it out include [[5edo]], [[10edo]], [[15edo]], [[20edo]], [[25edo]] and [[30edo]]. See [[Limmic temperaments]] for a number of other temperaments where it is tempered out. | ||
== Notation == | == Notation == | ||
In musical notations that | In musical notations that employ the [[5L 2s|diatonic]] [[chain-of-fifths notation|chain-of-fifths]], such as the [[ups and downs notation]], the limma is represented by the distances between B and C, as well as between E and F. | ||
This pattern highlights the placement of the limma intervals between | The scale is structured with the following step pattern: | ||
* A to B: [[9/8|whole tone]] | |||
* B to C: [[256/243|limma]] | |||
* C to D: [[9/8|whole tone]] | |||
* D to E: [[9/8|whole tone]] | |||
* E to F: [[256/243|limma]] | |||
* F to G: [[9/8|whole tone]] | |||
* G to A: [[9/8|whole tone]] | |||
This pattern highlights the placement of the limma intervals between the note pairs above, distinguishing them from the [[9/8|whole tone]] that occur between the other note pairs. | |||
== See also == | == See also == | ||
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[[Category:Semitone]] | [[Category:Semitone]] | ||
[[Category:Blackwood]] | [[Category:Blackwood]] | ||
[[Category:Commas named after composers]] | |||