Edϕ: Difference between revisions
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Various equal divisions of the octave have close approximations of [[acoustic phi]], or <math>φ</math>, ≈833.090296357¢. | |||
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<math>φ</math> is ≈1190.128995¢. | |||
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 <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" | ||
|+ | |+ | ||
| | | rowspan="2" |'''scale step''' | ||
| colspan="4" |'''10ed2''' | | colspan="4" |'''10ed2''' | ||
| colspan="4" |'''7edφ or 10ed(<math>2^{\frac{10log_2{φ}}{7}}</math>)''' | | colspan="4" |'''7edφ or 10ed(<math>2^{\frac{10log_2{φ}}{7}} ≈ 1.988629015</math>)''' | ||
|- | |- | ||
|'''frequency multiplier (definition)''' | |'''frequency multiplier (definition)''' | ||
|'''10ed2 frequency multiplier (decimal)''' | |'''10ed2 frequency multiplier (decimal)''' | ||
Line 28: | Line 29: | ||
|120 | |120 | ||
|120 | |120 | ||
|<math>φ^{\frac{1}{7}}</math> or <math> | |<math>φ^{\frac{1}{7}}</math> or <math>≈1.988629015^{\frac{1}{10}}</math> | ||
|1.071162542 | |1.071162542 | ||
|119.0128995 | |119.0128995 | ||
Line 38: | Line 39: | ||
|240 | |240 | ||
|120 | |120 | ||
|<math>φ^{\frac{2}{7}}</math> or <math> | |<math>φ^{\frac{2}{7}}</math> or <math>≈1.988629015^{\frac{2}{10}}</math> | ||
|1.147389191 | |1.147389191 | ||
|238.025799 | |238.025799 | ||
Line 48: | Line 49: | ||
|360 | |360 | ||
|120 | |120 | ||
|<math>φ^{\frac{3}{7}}</math> or <math> | |<math>φ^{\frac{3}{7}}</math> or <math>≈1.988629015^{\frac{3}{10}}</math> | ||
|1.229040323 | |1.229040323 | ||
|357.0386984 | |357.0386984 | ||
Line 58: | Line 59: | ||
|480 | |480 | ||
|120 | |120 | ||
|<math>φ^{\frac{4}{7}}</math> or <math> | |<math>φ^{\frac{4}{7}}</math> or <math>≈1.988629015^{\frac{4}{10}}</math> | ||
|1.316501956 | |1.316501956 | ||
|476.0515979 | |476.0515979 | ||
Line 68: | Line 69: | ||
|600 | |600 | ||
|120 | |120 | ||
|<math>φ^{\frac{5}{7}}</math> or <math> | |<math>φ^{\frac{5}{7}}</math> or <math>≈1.988629015^{\frac{5}{10}}</math> | ||
|1.410187582 | |1.410187582 | ||
|595.0644974 | |595.0644974 | ||
Line 78: | Line 79: | ||
|720 | |720 | ||
|120 | |120 | ||
|<math>φ^{\frac{6}{7}}</math> or <math> | |<math>φ^{\frac{6}{7}}</math> or <math>≈1.988629015^{\frac{6}{10}}</math> | ||
|1.510540115 | |1.510540115 | ||
|714.0773969 | |714.0773969 | ||
Line 88: | Line 89: | ||
|840 | |840 | ||
|120 | |120 | ||
|<math>φ^{\frac{7}{7}}</math> or <math> | |<math>φ^{\frac{7}{7}}</math> or <math>≈1.988629015^{\frac{7}{10}}</math> | ||
|1.618033989 | |1.618033989 | ||
|833.0902964 | |833.0902964 | ||
Line 98: | Line 99: | ||
|960 | |960 | ||
|120 | |120 | ||
|<math>φ^{\frac{8}{7}}</math> or <math> | |<math>φ^{\frac{8}{7}}</math> or <math>≈1.988629015^{\frac{8}{10}}</math> | ||
|1.7331774 | |1.7331774 | ||
|952.1031958 | |952.1031958 | ||
Line 108: | Line 109: | ||
|1080 | |1080 | ||
|120 | |120 | ||
|<math>φ^{\frac{9}{7}}</math> or <math> | |<math>φ^{\frac{9}{7}}</math> or <math>≈1.988629015^{\frac{9}{10}}</math> | ||
|1.85651471 | |1.85651471 | ||
|1071.116095 | |1071.116095 | ||
Line 118: | Line 119: | ||
|1200 | |1200 | ||
|120 | |120 | ||
|<math>φ^{\frac{10}{7}}</math> or <math> | |<math>φ^{\frac{10}{7}}</math> or <math>≈1.988629015^{\frac{10}{10}}</math> | ||
|1.988629015 | |1.988629015 | ||
|1190.128995 | |1190.128995 | ||
|119.0128995 | |119.0128995 | ||
|} | |} | ||
{| class="wikitable" | |||
|+ | |||
| rowspan="2" |'''scale step''' | |||
| colspan="4" |'''13ed2''' | |||
| colspan="4" |'''9edφ or 13ed(<math>2^{\frac{13log_2{φ}}{9}} ≈ 2.003876886</math>)''' | |||
|- | |||
|'''frequency multiplier (definition)''' | |||
|'''10ed2 frequency multiplier (decimal)''' | |||
|'''pitch (¢)''' | |||
|'''Δ (¢)''' | |||
|'''frequency multiplier (definition)''' | |||
|'''frequency multiplier (decimal)''' | |||
|'''pitch (¢)''' | |||
|'''Δ (¢)''' | |||
|- | |||
|'''1''' | |||
|<math>2^{\frac{1}{13}}</math> | |||
|1.054766076 | |||
|92.30769231 | |||
|92.30769231 | |||
|<math>φ^{\frac{1}{9}}</math> or <math>≈2.003876886^{\frac{1}{13}}</math> | |||
|1.054923213 | |||
|92.56558848 | |||
|92.56558848 | |||
|- | |||
|'''2''' | |||
|<math>2^{\frac{2}{13}}</math> | |||
|1.112531476 | |||
|184.6153846 | |||
|92.30769231 | |||
|<math>φ^{\frac{2}{9}}</math> or <math>≈2.003876886^{\frac{2}{13}}</math> | |||
|1.112862986 | |||
|185.131177 | |||
|92.56558848 | |||
|- | |||
|'''3''' | |||
|<math>2^{\frac{3}{13}}</math> | |||
|1.17346046 | |||
|276.9230769 | |||
|92.30769231 | |||
|<math>φ^{\frac{3}{9}}</math> or <math>≈2.003876886^{\frac{3}{13}}</math> | |||
|1.173984997 | |||
|277.6967655 | |||
|92.56558848 | |||
|- | |||
|'''4''' | |||
|<math>2^{\frac{4}{13}}</math> | |||
|1.237726285 | |||
|369.2307692 | |||
|92.30769231 | |||
|<math>φ^{\frac{4}{9}}</math> or <math>≈2.003876886^{\frac{4}{13}}</math> | |||
|1.238464025 | |||
|370.2623539 | |||
|92.56558848 | |||
|- | |||
|'''5''' | |||
|<math>2^{\frac{5}{13}}</math> | |||
|1.305511698 | |||
|461.5384615 | |||
|92.30769231 | |||
|<math>φ^{\frac{5}{9}}</math> or <math>≈2.003876886^{\frac{5}{13}}</math> | |||
|1.306484449 | |||
|462.8279424 | |||
|92.56558848 | |||
|- | |||
|'''6''' | |||
|<math>2^{\frac{6}{13}}</math> | |||
|1.377009451 | |||
|553.8461538 | |||
|92.30769231 | |||
|<math>φ^{\frac{6}{9}}</math> or <math>≈2.003876886^{\frac{6}{13}}</math> | |||
|1.378240772 | |||
|555.3935309 | |||
|92.56558848 | |||
|- | |||
|'''7''' | |||
|<math>2^{\frac{7}{13}}</math> | |||
|1.452422856 | |||
|646.1538462 | |||
|92.30769231 | |||
|<math>φ^{\frac{7}{9}}</math> or <math>≈2.003876886^{\frac{7}{13}}</math> | |||
|1.453938184 | |||
|647.9591194 | |||
|92.56558848 | |||
|- | |||
|'''8''' | |||
|<math>2^{\frac{8}{13}}</math> | |||
|1.531966357 | |||
|738.4615385 | |||
|92.30769231 | |||
|<math>φ^{\frac{8}{9}}</math> or <math>≈2.003876886^{\frac{8}{13}}</math> | |||
|1.533793141 | |||
|740.5247079 | |||
|92.56558848 | |||
|- | |||
|'''9''' | |||
|<math>2^{\frac{9}{13}}</math> | |||
|1.615866144 | |||
|830.7692308 | |||
|92.30769231 | |||
|<math>φ^{\frac{9}{9}}</math> or <math>≈2.003876886^{\frac{9}{13}}</math> | |||
|1.618033989 | |||
|833.0902964 | |||
|92.56558848 | |||
|- | |||
|'''10''' | |||
|<math>2^{\frac{10}{13}}</math> | |||
|1.704360793 | |||
|923.0769231 | |||
|92.30769231 | |||
|<math>φ^{\frac{10}{9}}</math> or <math>≈2.003876886^{\frac{10}{13}}</math> | |||
|1.706901614 | |||
|925.6558848 | |||
|92.56558848 | |||
|- | |||
|11 | |||
|<math>2^{\frac{11}{13}}</math> | |||
|1.797701946 | |||
|1015.384615 | |||
|92.30769231 | |||
|<math>φ^{\frac{11}{9}}</math> or <math>≈2.003876886^{\frac{11}{13}}</math> | |||
|1.800650136 | |||
|1018.221473 | |||
|92.56558848 | |||
|- | |||
|12 | |||
|<math>2^{\frac{12}{13}}</math> | |||
|1.896155029 | |||
|1107.692308 | |||
|92.30769231 | |||
|<math>φ^{\frac{12}{9}}</math> or <math>≈2.003876886^{\frac{12}{13}}</math> | |||
|1.899547627 | |||
|1110.787062 | |||
|92.56558848 | |||
|- | |||
|13 | |||
|<math>2^{\frac{13}{13}}</math> | |||
|2 | |||
|1200 | |||
|92.30769231 | |||
|<math>φ^{\frac{13}{9}}</math> or <math>≈2.003876886^{\frac{13}{13}}</math> | |||
|2.003876886 | |||
|1203.35265 | |||
|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}} |