65/64: Difference between revisions

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{{Infobox Interval
{{Infobox Interval
| Ratio = 65/64
| Monzo = -6 0 1 0 0 1
| Cents = 26.841376
| Name = wilsorma
| Name = wilsorma
| FJS name = P1<sup>65</sup>
| Color name = 3oy1, thoyo 1sn,<br>Thoyo comma
| Sound =  
| Comma = yes
}}
}}
In [[13-limit]] [[just intonation]], '''65/64''', the '''wilsorma''', is a [[superparticular]] interval of around 26.8{{cent}}, nearly a quarter of a semitone or eighth of a tone. 65 is 5 times 13, which means that 65/64 can be treated as a harmonic 13th above a harmonic 5th or vice versa. It is the difference between [[5/4]] and [[16/13]]; [[8/5]] and [[13/8]]; [[13/12]] and [[16/15]]; [[15/8]] and [[24/13]], [[13/10]] and [[32/25]]; [[20/13]] and [[25/16]], and of course, infinitely many other pairs of just intervals. It differs from the septimal comma [[64/63]] by [[4096/4095]] and from the syntonic comma [[81/80]] by [[325/324]].  
In [[13-limit]] [[just intonation]], '''65/64''', the '''wilsorma''', is a [[superparticular]] interval of around 26.8{{cent}}, nearly a quarter of a semitone or eighth of a tone. 65 is 5 times 13, which means that 65/64 can be treated as a harmonic 13th above a harmonic 5th or vice versa. It is the difference between [[5/4]] and [[16/13]]; [[8/5]] and [[13/8]]; [[13/12]] and [[16/15]]; [[15/8]] and [[24/13]], [[13/10]] and [[32/25]]; [[20/13]] and [[25/16]], and of course, infinitely many other pairs of just intervals. It differs from the septimal comma [[64/63]] by [[4096/4095]] and from the syntonic comma [[81/80]] by [[325/324]].  


Tempering it out turns 5/4 and 13/8 into [[octave complement]]s of one another. This is particularly useful in many [[13-limit]] [[magic family]] extensions, as it means they are very simply mapped to plus and minus one generator.   
Tempering it out turns 5/4 and 13/8 into [[octave complement]]s of one another. This is particularly useful in many [[13-limit]] [[magic family]] extensions, as it means they are very simply mapped to plus and minus one generator.
 
This interval is the 13th-partial chroma (13-limit formal comma) in [[Ben Johnston's notation]], denoted simply with the number "13", while its reciprocal is denoted as "{{invert|13}}" (a turned "13"). If the base note is C, then [[13/8]] is represented by C–Ab13.
 
Tempering it out leads to the rank-2 2.5.13 '''wilsormatic''' temperament, which has a generator tuned to abut 370-375 cents that represents both 5/4 and 16/13, or the rank-5 '''wilsormic''' temperament.   


== See also ==
== See also ==
Line 15: Line 16:
* [[64/63]]
* [[64/63]]


[[Category:13-limit]]
[[Category:Commas with unknown etymology]]
[[Category:Small commas]]
{{todo|research|comment=Is it named after Erv Wilson?}}
[[Category:Superparticular]]
[[Category:Octave-reduced harmonics]]

Latest revision as of 20:48, 1 June 2026

Interval information
Ratio 65/64
Factorization 2-6 × 5 × 13
Monzo [-6 0 1 0 0 1
Size in cents 26.84138¢
Name wilsorma
Color name 3oy1, thoyo 1sn,
Thoyo comma
FJS name [math]\displaystyle{ \text{P1}^{5,13} }[/math]
Special properties superparticular,
reduced,
reduced harmonic
Tenney norm (log2 nd) 12.0224
Weil norm (log2 max(n, d)) 12.0447
Wilson norm (sopfr(nd)) 30
Comma size small
S-expression S13⋅S14⋅S15
Open this interval in xen-calc

In 13-limit just intonation, 65/64, the wilsorma, is a superparticular interval of around 26.8 ¢, nearly a quarter of a semitone or eighth of a tone. 65 is 5 times 13, which means that 65/64 can be treated as a harmonic 13th above a harmonic 5th or vice versa. It is the difference between 5/4 and 16/13; 8/5 and 13/8; 13/12 and 16/15; 15/8 and 24/13, 13/10 and 32/25; 20/13 and 25/16, and of course, infinitely many other pairs of just intervals. It differs from the septimal comma 64/63 by 4096/4095 and from the syntonic comma 81/80 by 325/324.

Tempering it out turns 5/4 and 13/8 into octave complements of one another. This is particularly useful in many 13-limit magic family extensions, as it means they are very simply mapped to plus and minus one generator.

This interval is the 13th-partial chroma (13-limit formal comma) in Ben Johnston's notation, denoted simply with the number "13", while its reciprocal is denoted as "13" (a turned "13"). If the base note is C, then 13/8 is represented by C–Ab13.

Tempering it out leads to the rank-2 2.5.13 wilsormatic temperament, which has a generator tuned to abut 370-375 cents that represents both 5/4 and 16/13, or the rank-5 wilsormic temperament.

See also