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Various equal divisions of the octave have close approximations of acoustic phi, or | Various equal divisions of the octave have close approximations of [[acoustic phi]], or <math>φ</math>, ≈833.090296357¢. | ||
If the | If the <math>m^{th}</math> step of <math>n</math><span>ed2 is a close approximation of <math>φ</math>, the <math>n^{th}</math> step of <math>m</math><span>ed<math>φ</math> will be a close approximation of 2. | ||
For example, the 7th step of 10ed2 is 840¢, and the 10th step of 7ed | For example, the 7th step of 10ed2 is 840¢, and the 10th step of 7ed<math>φ</math> is ≈1190.128995¢. | ||
As another example, the 9th step of 13ed2 is ≈830.7692308¢, and the 13th step of 9ed | As another example, the 9th step of 13ed2 is ≈830.7692308¢, and the 13th step of [[9edϕ|9ed<math>φ</math>]] is ≈1203.35265¢. | ||
Such | Such <math>m</math><span>ed<math>φ</math> are interesting as variants of their respective <math>n</math><span>ed<math>2</math><span>, introducing some combination tone powers. | ||
{| class="wikitable" | {| class="wikitable" | ||
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|119.0128995 | |119.0128995 | ||
|} | |} | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
| rowspan="2" |'''scale step''' | | rowspan="2" |'''scale step''' | ||
| colspan="4" |'''13ed2''' | | colspan="4" |'''13ed2''' | ||
| colspan="4" |'''9edφ or 13ed(<math>2^{\frac{ | | colspan="4" |'''9edφ or 13ed(<math>2^{\frac{13log_2{φ}}{9}} ≈ 2.003876886</math>)''' | ||
|- | |- | ||
|'''frequency multiplier (definition)''' | |'''frequency multiplier (definition)''' | ||
Line 140: | Line 141: | ||
|- | |- | ||
|'''1''' | |'''1''' | ||
| | |<math>2^{\frac{1}{13}}</math> | ||
|1.054766076 | |1.054766076 | ||
|92.30769231 | |92.30769231 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{1}{9}}</math> or <math>≈2.003876886^{\frac{1}{13}}</math> | ||
|1.054923213 | |1.054923213 | ||
|92.56558848 | |92.56558848 | ||
Line 150: | Line 151: | ||
|- | |- | ||
|'''2''' | |'''2''' | ||
| | |<math>2^{\frac{2}{13}}</math> | ||
|1.112531476 | |1.112531476 | ||
|184.6153846 | |184.6153846 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{2}{9}}</math> or <math>≈2.003876886^{\frac{2}{13}}</math> | ||
|1.112862986 | |1.112862986 | ||
|185.131177 | |185.131177 | ||
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|- | |- | ||
|'''3''' | |'''3''' | ||
| | |<math>2^{\frac{3}{13}}</math> | ||
|1.17346046 | |1.17346046 | ||
|276.9230769 | |276.9230769 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{3}{9}}</math> or <math>≈2.003876886^{\frac{3}{13}}</math> | ||
|1.173984997 | |1.173984997 | ||
|277.6967655 | |277.6967655 | ||
Line 170: | Line 171: | ||
|- | |- | ||
|'''4''' | |'''4''' | ||
| | |<math>2^{\frac{4}{13}}</math> | ||
|1.237726285 | |1.237726285 | ||
|369.2307692 | |369.2307692 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{4}{9}}</math> or <math>≈2.003876886^{\frac{4}{13}}</math> | ||
|1.238464025 | |1.238464025 | ||
|370.2623539 | |370.2623539 | ||
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|- | |- | ||
|'''5''' | |'''5''' | ||
| | |<math>2^{\frac{5}{13}}</math> | ||
|1.305511698 | |1.305511698 | ||
|461.5384615 | |461.5384615 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{5}{9}}</math> or <math>≈2.003876886^{\frac{5}{13}}</math> | ||
|1.306484449 | |1.306484449 | ||
|462.8279424 | |462.8279424 | ||
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|- | |- | ||
|'''6''' | |'''6''' | ||
| | |<math>2^{\frac{6}{13}}</math> | ||
|1.377009451 | |1.377009451 | ||
|553.8461538 | |553.8461538 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{6}{9}}</math> or <math>≈2.003876886^{\frac{6}{13}}</math> | ||
|1.378240772 | |1.378240772 | ||
|555.3935309 | |555.3935309 | ||
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|- | |- | ||
|'''7''' | |'''7''' | ||
| | |<math>2^{\frac{7}{13}}</math> | ||
|1.452422856 | |1.452422856 | ||
|646.1538462 | |646.1538462 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{7}{9}}</math> or <math>≈2.003876886^{\frac{7}{13}}</math> | ||
|1.453938184 | |1.453938184 | ||
|647.9591194 | |647.9591194 | ||
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|- | |- | ||
|'''8''' | |'''8''' | ||
| | |<math>2^{\frac{8}{13}}</math> | ||
|1.531966357 | |1.531966357 | ||
|738.4615385 | |738.4615385 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{8}{9}}</math> or <math>≈2.003876886^{\frac{8}{13}}</math> | ||
|1.533793141 | |1.533793141 | ||
|740.5247079 | |740.5247079 | ||
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|- | |- | ||
|'''9''' | |'''9''' | ||
| | |<math>2^{\frac{9}{13}}</math> | ||
|1.615866144 | |1.615866144 | ||
|830.7692308 | |830.7692308 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{9}{9}}</math> or <math>≈2.003876886^{\frac{9}{13}}</math> | ||
|1.618033989 | |1.618033989 | ||
|833.0902964 | |833.0902964 | ||
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|- | |- | ||
|'''10''' | |'''10''' | ||
| | |<math>2^{\frac{10}{13}}</math> | ||
|1.704360793 | |1.704360793 | ||
|923.0769231 | |923.0769231 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{10}{9}}</math> or <math>≈2.003876886^{\frac{10}{13}}</math> | ||
|1.706901614 | |1.706901614 | ||
|925.6558848 | |925.6558848 | ||
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|- | |- | ||
|11 | |11 | ||
| | |<math>2^{\frac{11}{13}}</math> | ||
|1.797701946 | |1.797701946 | ||
|1015.384615 | |1015.384615 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{11}{9}}</math> or <math>≈2.003876886^{\frac{11}{13}}</math> | ||
|1.800650136 | |1.800650136 | ||
|1018.221473 | |1018.221473 | ||
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|- | |- | ||
|12 | |12 | ||
| | |<math>2^{\frac{12}{13}}</math> | ||
|1.896155029 | |1.896155029 | ||
|1107.692308 | |1107.692308 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{12}{9}}</math> or <math>≈2.003876886^{\frac{12}{13}}</math> | ||
|1.899547627 | |1.899547627 | ||
|1110.787062 | |1110.787062 | ||
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|- | |- | ||
|13 | |13 | ||
| | |<math>2^{\frac{13}{13}}</math> | ||
|2 | |2 | ||
|1200 | |1200 | ||
|92.30769231 | |92.30769231 | ||
| | |<math>φ^{\frac{13}{9}}</math> or <math>≈2.003876886^{\frac{13}{13}}</math> | ||
|2.003876886 | |2.003876886 | ||
|1203.35265 | |1203.35265 | ||
|92.56558848 | |92.56558848 | ||
|} | |} | ||
A couple such scales can be found in the [[Scala Scale Archive|Huygens-Fokker Foundation's Scala scale archive]]. They were described by Walter O'Connell in his 1993 paper [http://anaphoria.com/oconnell.pdf The Tonality of the Golden Section]. The 18th root of φ scale doubles the resolution of the 9th root scale featured above, as so as the 9th root of φ scale is similar to 13ed2 the 18th root of φ scale is similar to 26edo (which does a notably better job of approximating 3-, 5-, and 7- limit harmonies). | |||
cet33.scl 25 25th root of phi, Walter O´Connell (1993) | |||
cet46.scl 18 18th root of phi, Walter O´Connell (1993) | |||
== See also == | |||
* [[EDe]] | |||
* [[Acoustic pi]] | |||
* [[User:Eliora/Phi to the phi]] | |||
[[Category:Golden ratio]] | |||
{{todo|inline=1|improve synopsis|improve readability}} |