81/80: Difference between revisions
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{{Infobox Interval | {{Infobox Interval | ||
| Ratio = 81/80 | | Ratio = 81/80 | ||
| Cents = 21. | | Cents = 21.50629 | ||
| Monzo = -4 4 -1 | | Monzo = -4 4 -1 | ||
| Name = syntonic comma, <br | | Name = syntonic comma, <br>Didymus comma, <br>meantone comma | ||
| Color name = g1, Gu comma, <br/> gu unison | | Color name = g1, Gu comma, <br/> gu unison | ||
| FJS name = P1<sub>5</sub> | | FJS name = P1<sub>5</sub> | ||
| Sound = | | Sound = | ||
}} | }} | ||
{{Wikipedia|Syntonic comma}} | |||
The '''syntonic''' or '''Didymus''' or '''meantone comma''' (frequency ratio '''81/80''') is helpful for comparing [[3-limit]] and 5-limit [[just intonation]]. Adding or subtracting this comma to/from any 3-limit [[ratio]] with an [[odd limit]] of 27 or higher creates a 5-limit ratio with a much lower odd-limit. Thus dissonant 3-limit harmonies can often be sweetened via a commatic adjustment. However adding/subtracting this comma to/from any 3-limit ratio of odd limit 3 or less (the 4th, 5th or 8ve), creates a wolf interval of odd limit 27 or higher. Any attempt to tune a fixed-pitch instrument (e.g. guitar or piano) to 5-limit just intonation will create such wolves, thus tempering out 81/80 is desirable. This gives a tuning for the [[Tone|whole tone]] which is intermediate between 10/9 and 9/8, and leads to [[Meantone | The '''syntonic''' or '''Didymus''' or '''meantone comma''' (frequency ratio '''81/80''') is helpful for comparing [[3-limit]] and [[5-limit]] [[just intonation]]. Adding or subtracting this comma to/from any 3-limit [[ratio]] with an [[odd limit]] of 27 or higher creates a 5-limit ratio with a much lower odd-limit. Thus dissonant 3-limit harmonies can often be sweetened via a commatic adjustment. However, adding/subtracting this comma to/from any 3-limit ratio of odd limit 3 or less (the 4th, 5th or 8ve), creates a wolf interval of odd limit 27 or higher. Any attempt to tune a fixed-pitch instrument (e.g. guitar or piano) to 5-limit just intonation will create such wolves, thus tempering out 81/80 is desirable. This gives a tuning for the [[Tone|whole tone]] which is intermediate between 10/9 and 9/8, and leads to [[Meantone|meantone temperament]], hence the name meantone comma. | ||
Tempering out a comma does not just depend on an EDO's size; [[105edo]] tempers 81/80 out, while [[15edo|3edo]] does not. | Tempering out a comma does not just depend on an EDO's size; [[105edo]] tempers 81/80 out, while [[15edo|3edo]] does not. | ||
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If one should be so bold as to treat the syntonic comma as a musical interval in its own right as opposed to tempering it out, one can easily use it in melodies as either an [[Wikipedia:Appoggiatura|appoggitura]], an [[Wikipedia:Acciaccatura|acciaccatura]], or a quick passing tone. Furthermore, it is also very easy to exploit in [[comma pump]] modulations, as among the [[Meantone comma pump examples|known examples]] of this kind of thing are familiar-sounding chord progressions. | If one should be so bold as to treat the syntonic comma as a musical interval in its own right as opposed to tempering it out, one can easily use it in melodies as either an [[Wikipedia:Appoggiatura|appoggitura]], an [[Wikipedia:Acciaccatura|acciaccatura]], or a quick passing tone. Furthermore, it is also very easy to exploit in [[comma pump]] modulations, as among the [[Meantone comma pump examples|known examples]] of this kind of thing are familiar-sounding chord progressions. | ||
[[Monroe Golden]]'s ''Incongruity'' uses just-intonation chord progressions that exploit this comma<ref>[http://untwelve.org/interviews/golden UnTwelve's interview to Monroe Golden]</ref>. | |||
== Relations to other superparticular ratios == | |||
Superparticular ratios, like 81/80, can be expressed as products or quotients of other superparticular ratios. Following is a list of such representations r1 * r2 or r2 / r1 of 81/80, where r1 and r2 are other superparticular ratios. | Superparticular ratios, like 81/80, can be expressed as products or quotients of other superparticular ratios. Following is a list of such representations r1 * r2 or r2 / r1 of 81/80, where r1 and r2 are other superparticular ratios. | ||
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== | == See also == | ||
* [[160/81]] – its [[octave complement]] | |||
* [[40/27]] – its [[fifth complement]] | |||
* [[Small comma]] | |||
* [[List of superparticular intervals]] | |||
== Notes == | |||
[[Category:5-limit]] | [[Category:5-limit]] | ||
[[Category:Small comma]] | [[Category:Small comma]] | ||
[[Category:Interval]] | [[Category:Interval]] | ||
[[Category:Ratio]] | |||
[[Category:Superparticular]] | [[Category:Superparticular]] | ||
[[Category: | [[Category:Meantone]] | ||
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[[de:81/80]] | [[de:81/80]] |