12edo: Difference between revisions

clarify what the 12edo thirds are being compared to. We are a wiki, not a 31edo propaganda channel
Octave stretch or compression: unify precision. Note prime 2. Misc. fixes
 
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It is the smallest number of equal divisions of the octave ([[edo]]) which can seriously claim to represent [[5-limit]] harmony, and because it represents a [[meantone]] temperament (specifically {{frac|1|12}} Pythagorean comma meantone, or approximately {{frac|1|11}} syntonic comma or full schisma meantone).
It is the smallest number of equal divisions of the octave ([[edo]]) which can seriously claim to represent [[5-limit]] harmony, and because it represents a [[meantone]] temperament (specifically {{frac|1|12}} Pythagorean comma meantone, or approximately {{frac|1|11}} syntonic comma or full schisma meantone).


It divides the octave into twelve equal parts, each of exactly 100 [[cent]]s each unless [[stretched and compressed tuning|octave stretching or compression]] is employed. It has a [[3/2|fifth]] which is quite accurate at 700 cents, two cents flat of just. It has a [[5/4|major third]] which is 13.7 cents sharp of 5/4, which, while reasonable for its size, is unsatisfactory for some. The [[6/5|minor third]] is flat of 6/5 by even more, 15.6 cents.
It divides the octave into twelve equal parts, each of exactly 100 [[cent]]s each unless [[stretched and compressed tuning|octave stretching or compression]] is employed. It has a [[3/2|fifth]] which is quite accurate at 700 cents, two cents flat of just. It has a [[5/4|major third]] which is 13.7 cents sharp of just, which, while reasonable for its size, is unsatisfactory for some. The [[6/5|minor third]] is flat of just by even more, 15.6 cents.


Historically, 12edo became dominant primarily due to practical considerations for keyboard instruments and its ability to handle modulation across all keys with reasonable intonation.
Historically, 12edo became dominant primarily due to practical considerations for keyboard instruments and its ability to handle modulation across all keys with reasonable intonation.
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=== Prime harmonics ===
=== Prime harmonics ===
{{Harmonics in equal|12|prec=2}}
{{Harmonics in equal|12|prec=2}}
=== Octave stretch ===
Whether there is intonational improvement from [[stretched and compressed tuning|octave stretch and compression]] for 12edo varies by context. A slight compression such as what is given by [[40ed10]] and the [[The Riemann zeta function and tuning|zeta-optimized]] 99.81{{c}} step size shows improved intonation of harmonics 5 and 7 at the cost of worse 2 and 3, while stretching the octave for a purer 3 and for a better match of the inharmonicity on string instruments, like those in [[7edf]], [[19edt]], or [[31ed6]], also makes sense.


=== Subsets and supersets ===
=== Subsets and supersets ===
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<nowiki/>* [[Normal lists|Octave-reduced form]], reduced to the first half-octave, and [[Normal lists|minimal form]] in parentheses if distinct
<nowiki/>* [[Normal lists|Octave-reduced form]], reduced to the first half-octave, and [[Normal lists|minimal form]] in parentheses if distinct
== Octave stretch or compression ==
Whether there is intonational improvement from [[stretched and compressed tuning|octave stretch and compression]] for 12edo varies by context. A slight compression such as what is given by [[40ed10]] and the [[the Riemann zeta function and tuning|zeta-optimized]] 99.81{{c}} step size shows improved intonation of harmonics [[5/1|5]] and [[7/1|7]] at the cost of worse [[2/1|2]] and [[3/1|3]], while stretching the octave for a purer 3 and for a better match of the inharmonicity on string instruments, like those in [[7edf]], [[19edt]], or [[31ed6]], also makes sense.
; [[WE|12et, 7-limit WE tuning]]
* Step size: 99.664{{c}}, octave size: 1195.971{{c}}
Compressing the octave of 12edo by 4{{c}} results in much improved primes 5, 7 and 11, but much worse primes 2 and 3. Both 7-limit [[WE]] and [[TE]] tuning do this. [[40ed10]] does this as well. An argument could be made that such tunings enable [[7-limit|harmonies involving the 7th harmonic]] to regular old 12edo without even needing to add any new notes to the octave. This adds in brand new harmonic possibilities without breaking any common 12-tone music theory.
{{Harmonics in cet|99.664256|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 12et, 7-limit WE tuning}}
{{Harmonics in cet|99.664256|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 12et, 7-limit WE tuning (continued)}}
; [[ZPI|34zpi]]
* Step size: 99.807{{c}}, octave size: 1197.686{{c}}
Compressing the octave of 12edo by around 2{{c}} results in improved primes 5 and 7, but worse primes 2 and 3. The tuning 34zpi does this. It might be a good tuning for 5-limit [[meantone]], for composers seeking more pure thirds and sixths than regular 12edo. It would be well suited for playing classic pieces written for [[historical temperaments]], as well as being well suited to playing simultaneously with other instruments or voices that use [[just intonation]].
{{Harmonics in cet|99.807|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 34zpi}}
{{Harmonics in cet|99.807|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 34zpi (continued)}}
; [[WE|12et, 5-limit WE tuning]]
* Step size: 99.868{{c}}, octave size: 1198.416{{c}}
Compressing the octave of 12edo by around 1{{c}} results in slightly improved primes 5 and 7, but slightly worse primes 2 and 3. Both 5-limit WE and TE tuning do this. This has the same benefits and drawbacks as 34zpi, but both are less intense here compared to 34zpi.
{{Harmonics in cet|99.868021|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 12et, 5-limit WE tuning}}
{{Harmonics in cet|99.868021|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 12et, 5-limit WE tuning (continued)}}
; 12edo
* Step size: 100.000{{c}}, octave size: 1200.000{{c}}
Pure-octaves 12edo performs well on harmonics 2, 3 and 5 but poorly on harmonics 7, 11 and 13 compared to other edos with a similar number of notes per octave.
{{Harmonics in equal|12|2|1|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 12edo}}
{{Harmonics in equal|12|2|1|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 12edo (continued)}}
; [[31ed6]]
* Step size: 100.063{{c}}, octave size: 1200.757{{c}}
Stretching the octave of 12edo by a little less than 1{{c}} results in an improved prime 3, but worse primes 2, 5, and 7. This loosely resembles the stretched-octave tunings commonly used on pianos. It may better match the [[timbre|slightly inharmonic partials]] of some string instruments. The tuning 31ed6 does this.
{{Harmonics in equal|31|6|1|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 31ed6}}
{{Harmonics in equal|31|6|1|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 31ed6 (continued)}}
; [[19edt]]
* Step size: 101.103{{c}}, octave size: 1201.235{{c}}
Stretching the octave of 12edo by a little more than 1{{c}} results in an improved prime 3, but worse primes 2, 5, and 7. It may better match the [[timbre|slightly inharmonic partials]] of some string instruments. The tuning 19edt does this.
{{Harmonics in equal|19|3|1|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 19edt}}
{{Harmonics in equal|19|3|1|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 19edt (continued)}}
; [[7edf]]
* Step size: 100.279{{c}}, octave size: 1203.351{{c}}
Stretching the octave of 12edo by around 3{{c}} results in improved primes 3 and 13, but much worse primes 2, 5, and 7. This has similar benefits and drawbacks to [[Pythagorean]] tuning. Most modern music probably will not sound very good here because of the off 5th harmonic. The tuning 7edf does this.
{{Harmonics in equal|7|3|2|intervals=integer|columns=11|collapsed=true|title=Approximation of harmonics in 7edf}}
{{Harmonics in equal|7|3|2|intervals=integer|columns=12|start=12|collapsed=true|title=Approximation of harmonics in 7edf (continued)}}


== Scales ==
== Scales ==