81/80: Difference between revisions

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{{Infobox Interval
{{Infobox Interval
| Icon =
| Ratio = 81/80
| Ratio = 81/80
| Cents = 21.506290
| Cents = 21.50629
| Monzo = -4 4 -1
| Monzo = -4 4 -1
| Name = syntonic comma, <br/> Didymus comma, <br/> meantone comma
| 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 family|meantone temperament]], hence the name meantone 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|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.


According to [http://untwelve.org/interviews/golden.html this interview] {{dead link}}, Monroe Golden's ''Incongruity'' uses just-intonation chord progressions that exploit this comma.
[[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 ==


== 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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== External Links ==
== See also ==
* [[160/81]] – its [[octave complement]]
* [[40/27]] – its [[fifth complement]]
* [[Small comma]]
* [[List of superparticular intervals]]


* [[Wikipedia: Syntonic comma]]
== Notes ==


[[Category:5-limit]]
[[Category:5-limit]]
[[Category:Small comma]]
[[Category:Small comma]]
[[Category:Definition]]
[[Category:Interval]]
[[Category:Interval]]
[[Category:Ratio]]
[[Category:Superparticular]]
[[Category:Superparticular]]
[[Category:Syntonic]]
[[Category:Meantone]]


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[[de:81/80]]
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