18edo: Difference between revisions

Wikispaces>igliashon
**Imported revision 241890068 - Original comment: **
Wikispaces>igliashon
**Imported revision 243534697 - Original comment: **
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<h2>IMPORTED REVISION FROM WIKISPACES</h2>
<h2>IMPORTED REVISION FROM WIKISPACES</h2>
This is an imported revision from Wikispaces. The revision metadata is included below for reference:<br>
This is an imported revision from Wikispaces. The revision metadata is included below for reference:<br>
: This revision was by author [[User:igliashon|igliashon]] and made on <tt>2011-07-19 01:23:21 UTC</tt>.<br>
: This revision was by author [[User:igliashon|igliashon]] and made on <tt>2011-07-30 17:50:41 UTC</tt>.<br>
: The original revision id was <tt>241890068</tt>.<br>
: The original revision id was <tt>243534697</tt>.<br>
: The revision comment was: <tt></tt><br>
: The revision comment was: <tt></tt><br>
The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.<br>
The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.<br>
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==Basic Properties==  
==Basic Properties==  
18-EDO divides the octave into 18 equal parts of ~66.667 cents each. It does not approximate the 3rd harmonic at all, unless a &gt;30¢-error is considered acceptable, and it approximates the 5th and 7th harmonics equally with 12-TET. It does, however, render a most accurate tuning of 9/8, 7/6, 21/16, 15/11, 12/7, 16/9, and 13/7. It is also the smallest EDO to approximate the harmonic series chord 5:6:7 without tempering out 36/35 (and thus without using the same interval to approximate both 6/5 and 7/6).  
18-EDO divides the octave into 18 equal parts of ~66.667 cents each. It does not approximate the 3rd harmonic at all, unless a &gt;30¢-error is considered acceptable, and it approximates the 5th and 7th harmonics equally with 12-TET. It does, however, render a most accurate tuning of 9/8, 7/6, 21/16, 15/11, 12/7, 16/9, and 13/7. It is also the smallest EDO to approximate the harmonic series chord 5:6:7 without tempering out 36/35 (and thus without using the same interval to approximate both 6/5 and 7/6).


In order to access the excellent consonances actually available, one must take a considerably "non-common-practice" approach, meaning to avoid the usual closed-voice "root-3rd-5th" type of chord and instead use chords which are either more compressed or more stretched out. 18-EDO may be treated as a temperament of the 17-limit [[k*N subgroups|4*18 subgroup]] [[Just intonation subgroups|just intonation subgroup]] 2.9.75.21.55.39.51. On this subgroup it tempers out exactly the same commas as 72 does on the full [[17-limit]], and gives precisely the same tunings. The subgroup can be put into a single chord, for example 32:36:39:42:51:55:64:75 (in terms of 18edo, 0-3-5-7-12-14-18-22), and transpositions and inversions of this chord or its subchords provide plenty of harmonic resources.
In order to access the excellent consonances actually available, one must take a considerably "non-common-practice" approach, meaning to avoid the usual closed-voice "root-3rd-5th" type of chord and instead use chords which are either more compressed or more stretched out. 18-EDO may be treated as a temperament of the 17-limit [[k*N subgroups|4*18 subgroup]] [[Just intonation subgroups|just intonation subgroup]] 2.9.75.21.55.39.51. On this subgroup it tempers out exactly the same commas as 72 does on the full [[17-limit]], and gives precisely the same tunings. The subgroup can be put into a single chord, for example 32:36:39:42:51:55:64:75 (in terms of 18edo, 0-3-5-7-12-14-18-22), and transpositions and inversions of this chord or its subchords provide plenty of harmonic resources.
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===Representations of Just Intervals===  
===Representations of Just Intervals===  
|| Degree || Cents || Nearest Ratio || Error (cents) || 17-Limit Ratios* ||
|| Degree || Cents ||= 5L3s Notation || Nearest Ratio || Error (cents) || 17-Limit Ratios* ||
|| 0 || 0 || 1/1 || 0 || **1/1** ||
|| 0 || 0 ||= **C** || 1/1 || 0 || **1/1** ||
|| 1 || 66.667 || 27/26 || +1.329 ||&gt; 78/75, 75/72 ||
|| 1 || 66.667 ||= Db || 27/26 || +1.329 ||&gt; 78/75, 75/72 ||
|| 2 || 133.333 || 27/25 || +0.096 ||&gt; 51/55, 42/39 ||
|| 2 || 133.333 ||= C# || 27/25 || +0.096 ||&gt; 51/55, 42/39 ||
|| 3 || 200 || 9/8 || -3.910 || **9/8** ||
|| 3 || 200 ||= **D** || 9/8 || -3.910 || **9/8** ||
|| 4 || 266.667 || 7/6 || -0.204 || **75/64** ||
|| 4 || 266.667 ||= Eb || 7/6 || -0.204 || **75/64** ||
|| 5 || 333.333 || 17/14 or 40/33 || -2.796 +0.293 || **39/32** ||
|| 5 || 333.333 ||= D# || 17/14 or 40/33 || -2.796 +0.293 || **39/32** ||
|| 6 || 400 || 5/4 or 44/35 || +13.686 +3.822 ||&gt; 64/55 ||
|| 6 || 400 ||= **E** || 5/4 or 44/35 || +13.686 +3.822 ||&gt; 64/55 ||
|| 7 || 466.667 || 21/16 || -4.114 || **21/16** ||
|| 7 || 466.667 ||= **F** || 21/16 || -4.114 || **21/16** ||
|| 8 || 533.333 || 15/11 || -3.617 ||&gt; 102/75 ||
|| 8 || 533.333 ||= Gb || 15/11 || -3.617 ||&gt; 102/75 ||
|| 9 || 600 || 17/12 or 24/17 || -3.000 +3.000 ||&gt; 17/12 ||
|| 9 || 600 ||= F# || 17/12 or 24/17 || -3.000 +3.000 ||&gt; 17/12 ||
|| 10 || 666.667 || 22/15 || +3.617 ||&gt; 75/51 ||
|| 10 || 666.667 ||= **G** || 22/15 || +3.617 ||&gt; 75/51 ||
|| 11 || 733.333 || 32/21 || +4.114 ||&gt; 32/21 ||
|| 11 || 733.333 ||= Hb || 32/21 || +4.114 ||&gt; 32/21 ||
|| 12 || 800 || 8/5 or 35/22 || -13.686 -3.8222 || **51/32** ||
|| 12 || 800 ||= G# || 8/5 or 35/22 || -13.686 -3.8222 || **51/32** ||
|| 13 || 866.667 || 28/17 or 33/20 || +2.796 -0.293 ||&gt; 64/39 ||
|| 13 || 866.667 ||= **H** || 28/17 or 33/20 || +2.796 -0.293 ||&gt; 64/39 ||
|| 14 || 933.333 || 12/7 || +0.204 || **55/32** ||
|| 14 || 933.333 ||= **A** || 12/7 || +0.204 || **55/32** ||
|| 15 || 1000 || 16/9 || +3.910 ||&gt; 16/9 ||
|| 15 || 1000 ||= Bb || 16/9 || +3.910 ||&gt; 16/9 ||
|| 16 || 1066.667 || 50/27 || -0.096 ||&gt; 39/21 ||
|| 16 || 1066.667 ||= A# || 50/27 || -0.096 ||&gt; 39/21 ||
|| 17 || 1133.333 || 52/27 || -1.329 ||&gt; 75/39 ||
|| 17 || 1133.333 ||= **B** || 52/27 || -1.329 ||&gt; 75/39 ||
|| 18 || 1200 || 2/1 || 0 || **2/1** ||
|| 18 || 1200 ||= **C** || 2/1 || 0 || **2/1** ||
*based on the above description of 18-EDO as a 2.9.75.21.55.39.51 subgroup temperament
*based on the above description of 18-EDO as a 2.9.75.21.55.39.51 subgroup temperament


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&lt;br /&gt;
&lt;br /&gt;
&lt;!-- ws:start:WikiTextHeadingRule:2:&amp;lt;h2&amp;gt; --&gt;&lt;h2 id="toc1"&gt;&lt;a name="x18 Equal Divisions of the Octave-Basic Properties"&gt;&lt;/a&gt;&lt;!-- ws:end:WikiTextHeadingRule:2 --&gt;Basic Properties&lt;/h2&gt;
&lt;!-- ws:start:WikiTextHeadingRule:2:&amp;lt;h2&amp;gt; --&gt;&lt;h2 id="toc1"&gt;&lt;a name="x18 Equal Divisions of the Octave-Basic Properties"&gt;&lt;/a&gt;&lt;!-- ws:end:WikiTextHeadingRule:2 --&gt;Basic Properties&lt;/h2&gt;
  18-EDO divides the octave into 18 equal parts of ~66.667 cents each. It does not approximate the 3rd harmonic at all, unless a &amp;gt;30¢-error is considered acceptable, and it approximates the 5th and 7th harmonics equally with 12-TET. It does, however, render a most accurate tuning of 9/8, 7/6, 21/16, 15/11, 12/7, 16/9, and 13/7. It is also the smallest EDO to approximate the harmonic series chord 5:6:7 without tempering out 36/35 (and thus without using the same interval to approximate both 6/5 and 7/6). &lt;br /&gt;
  18-EDO divides the octave into 18 equal parts of ~66.667 cents each. It does not approximate the 3rd harmonic at all, unless a &amp;gt;30¢-error is considered acceptable, and it approximates the 5th and 7th harmonics equally with 12-TET. It does, however, render a most accurate tuning of 9/8, 7/6, 21/16, 15/11, 12/7, 16/9, and 13/7. It is also the smallest EDO to approximate the harmonic series chord 5:6:7 without tempering out 36/35 (and thus without using the same interval to approximate both 6/5 and 7/6).&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
In order to access the excellent consonances actually available, one must take a considerably &amp;quot;non-common-practice&amp;quot; approach, meaning to avoid the usual closed-voice &amp;quot;root-3rd-5th&amp;quot; type of chord and instead use chords which are either more compressed or more stretched out. 18-EDO may be treated as a temperament of the 17-limit &lt;a class="wiki_link" href="/k%2AN%20subgroups"&gt;4*18 subgroup&lt;/a&gt; &lt;a class="wiki_link" href="/Just%20intonation%20subgroups"&gt;just intonation subgroup&lt;/a&gt; 2.9.75.21.55.39.51. On this subgroup it tempers out exactly the same commas as 72 does on the full &lt;a class="wiki_link" href="/17-limit"&gt;17-limit&lt;/a&gt;, and gives precisely the same tunings. The subgroup can be put into a single chord, for example 32:36:39:42:51:55:64:75 (in terms of 18edo, 0-3-5-7-12-14-18-22), and transpositions and inversions of this chord or its subchords provide plenty of harmonic resources.&lt;br /&gt;
In order to access the excellent consonances actually available, one must take a considerably &amp;quot;non-common-practice&amp;quot; approach, meaning to avoid the usual closed-voice &amp;quot;root-3rd-5th&amp;quot; type of chord and instead use chords which are either more compressed or more stretched out. 18-EDO may be treated as a temperament of the 17-limit &lt;a class="wiki_link" href="/k%2AN%20subgroups"&gt;4*18 subgroup&lt;/a&gt; &lt;a class="wiki_link" href="/Just%20intonation%20subgroups"&gt;just intonation subgroup&lt;/a&gt; 2.9.75.21.55.39.51. On this subgroup it tempers out exactly the same commas as 72 does on the full &lt;a class="wiki_link" href="/17-limit"&gt;17-limit&lt;/a&gt;, and gives precisely the same tunings. The subgroup can be put into a single chord, for example 32:36:39:42:51:55:64:75 (in terms of 18edo, 0-3-5-7-12-14-18-22), and transpositions and inversions of this chord or its subchords provide plenty of harmonic resources.&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;Cents&lt;br /&gt;
         &lt;td&gt;Cents&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;5L3s Notation&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;Nearest Ratio&lt;br /&gt;
         &lt;td&gt;Nearest Ratio&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;0&lt;br /&gt;
         &lt;td&gt;0&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;C&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;1/1&lt;br /&gt;
         &lt;td&gt;1/1&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;66.667&lt;br /&gt;
         &lt;td&gt;66.667&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;Db&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;27/26&lt;br /&gt;
         &lt;td&gt;27/26&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;133.333&lt;br /&gt;
         &lt;td&gt;133.333&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;C#&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;27/25&lt;br /&gt;
         &lt;td&gt;27/25&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;200&lt;br /&gt;
         &lt;td&gt;200&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;D&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;9/8&lt;br /&gt;
         &lt;td&gt;9/8&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;266.667&lt;br /&gt;
         &lt;td&gt;266.667&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;Eb&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;7/6&lt;br /&gt;
         &lt;td&gt;7/6&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;333.333&lt;br /&gt;
         &lt;td&gt;333.333&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;D#&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;17/14 or 40/33&lt;br /&gt;
         &lt;td&gt;17/14 or 40/33&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;400&lt;br /&gt;
         &lt;td&gt;400&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;E&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;5/4 or 44/35&lt;br /&gt;
         &lt;td&gt;5/4 or 44/35&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;466.667&lt;br /&gt;
         &lt;td&gt;466.667&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;F&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;21/16&lt;br /&gt;
         &lt;td&gt;21/16&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;533.333&lt;br /&gt;
         &lt;td&gt;533.333&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;Gb&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;15/11&lt;br /&gt;
         &lt;td&gt;15/11&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;600&lt;br /&gt;
         &lt;td&gt;600&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;F#&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;17/12 or 24/17&lt;br /&gt;
         &lt;td&gt;17/12 or 24/17&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;666.667&lt;br /&gt;
         &lt;td&gt;666.667&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;G&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;22/15&lt;br /&gt;
         &lt;td&gt;22/15&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;733.333&lt;br /&gt;
         &lt;td&gt;733.333&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;Hb&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;32/21&lt;br /&gt;
         &lt;td&gt;32/21&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;800&lt;br /&gt;
         &lt;td&gt;800&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;G#&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;8/5 or 35/22&lt;br /&gt;
         &lt;td&gt;8/5 or 35/22&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;866.667&lt;br /&gt;
         &lt;td&gt;866.667&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;H&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;28/17 or 33/20&lt;br /&gt;
         &lt;td&gt;28/17 or 33/20&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;933.333&lt;br /&gt;
         &lt;td&gt;933.333&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;A&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;12/7&lt;br /&gt;
         &lt;td&gt;12/7&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;1000&lt;br /&gt;
         &lt;td&gt;1000&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;Bb&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;16/9&lt;br /&gt;
         &lt;td&gt;16/9&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;1066.667&lt;br /&gt;
         &lt;td&gt;1066.667&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;A#&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;50/27&lt;br /&gt;
         &lt;td&gt;50/27&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;1133.333&lt;br /&gt;
         &lt;td&gt;1133.333&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;B&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;52/27&lt;br /&gt;
         &lt;td&gt;52/27&lt;br /&gt;
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&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;1200&lt;br /&gt;
         &lt;td&gt;1200&lt;br /&gt;
&lt;/td&gt;
        &lt;td style="text-align: center;"&gt;&lt;strong&gt;C&lt;/strong&gt;&lt;br /&gt;
&lt;/td&gt;
&lt;/td&gt;
         &lt;td&gt;2/1&lt;br /&gt;
         &lt;td&gt;2/1&lt;br /&gt;