Pentacircle chords: Difference between revisions

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It's important to single ou the palindromic triad cuz it's the most fundamental form of these chords. The rest can be viewed as variations on it
 
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A '''pentacircle chord''' is an [[essentially tempered dyadic chord]] in the 2.9.7.11 subgroup in the 11-odd-limit, tempering out the [[pentacircle comma]], 896/891. The pentacircle triads are three in number, 1-9/7-16/9 with steps 9/7-11/8-9/8; 1-9/7-16/11 with steps 9/7-9/8-11/8; and 1-11/7-16/9 with steps 11/7-9/8-9/8. There are six pentacircle tetrads: the palindromic 1-9/8-14/9-7/4 with steps 9/8-11/8-9/8-8/7; the palindromic 1-9/8-11/8-14/9 with steps 9/8-11/9-9/8-9/7; the inverse pair 1-11/8-11/7-16/9 with steps 11/8-8/7-9/8-9/8 and 1-11/8-14/9-7/4 with steps 11/8-9/8-9/8-8/7; and the inverse pair 1-11/9-11/7-16/9 with steps 11/9-9/7-9/8-9/8 and 1-11/9-11/8-14/9 with steps 11/9-9/8-9/8-9/7. Finally, there are two pentacircle pentads, inversely related: 1-11/9-11/8-11/7-16/9 with steps 11/9-9/8-8/7-9/8-9/8 and 1-11/9-11/8-14/9-16/9 with steps 11/9-9/8-9/8-8/7-9/8.
A '''pentacircle chord''' is an [[essentially tempered dyadic chord]] in the 2.9.7.11 [[subgroup]] in the [[11-odd-limit]], [[tempering out]] the pentacircle comma, [[896/891]].  


The count of chords is triads: 3, tetrads: 6, pentads: 2, for a total of 11.
Pentacircle chords are of [[Dyadic chord/Pattern of essentially tempered chords|pattern 1b]] in the 2.9.7.11 [[subgroup]] [[11-odd-limit]], meaning that there are 3 [[triad]]s, 6 [[tetrad]]s and 2 [[pentad]]s, for a total of 11 distinct chord structures.  


Equal divisions with pentacircle chords include 22, 27, 41, 46, 58, 68, 80, 87, 121, 145, 167, 208, 266e and 433bce.
The three pentacircle triads include a palindrome since it identifies [[14/11]] by a stack of two [[9/8]]'s:
* 1–9/8–14/11 with steps 9/8, 9/8, 11/7.  


[[Category:11-odd-limit]]
And an inversely related pair:
[[Category:Chords]]
* 1–9/8–16/11 with steps 9/8, 9/7, 11/8;
* 1–9/8–14/9 with steps 9/8, 11/8, 9/7;
 
The tetrads include the palindromic
* 1–9/8–14/9–7/4 with steps 9/8, 11/8, 9/8, 8/7;
* 1–9/8–11/8–14/9 with steps 9/8, 11/9, 9/8, 9/7.
 
And the inversely related pairs
* 1–11/8–11/7–16/9 with steps 11/8, 8/7, 9/8, 9/8, and its inverse
* 1–11/8–14/9–7/4 with steps 11/8, 9/8, 9/8, 8/7;
* 1–11/9–11/7–16/9 with steps 11/9, 9/7, 9/8, 9/8, and its inverse
* 1–11/9–11/8–14/9 with steps 11/9, 9/8, 9/8, 9/7.
 
Finally, there are two pentacircle pentads, inversely related:
* 1–11/9–11/8–11/7–16/9 with steps 11/9, 9/8, 8/7, 9/8, 9/8, and its inverse
* 1–11/9–11/8–14/9–16/9 with steps 11/9, 9/8, 9/8, 8/7, 9/8.
 
[[Equal temperament]]s with pentacircle chords include {{EDOs| 22, 27, 41, 46, 58, 68, 80, 87, 121, 145, 167, and 208 }}, with 208edo giving the [[optimal patent val]].
 
[[Category:11-odd-limit chords]]
[[Category:Essentially tempered chords]]
[[Category:Essentially tempered chords]]
[[Category:Triads]]
[[Category:Tetrads]]
[[Category:Pentads]]
[[Category:Pentacircle]]
[[Category:Pentacircle]]
[[Category:Tetrad]]
[[Category:Todo:add links]]