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- | : 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> | : 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 >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 >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 ||> 78/75, 75/72 || | || 1 || 66.667 ||= Db || 27/26 || +1.329 ||> 78/75, 75/72 || | ||
|| 2 || 133.333 || 27/25 || +0.096 ||> 51/55, 42/39 || | || 2 || 133.333 ||= C# || 27/25 || +0.096 ||> 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 ||> 64/55 || | || 6 || 400 ||= **E** || 5/4 or 44/35 || +13.686 +3.822 ||> 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 ||> 102/75 || | || 8 || 533.333 ||= Gb || 15/11 || -3.617 ||> 102/75 || | ||
|| 9 || 600 || 17/12 or 24/17 || -3.000 +3.000 ||> 17/12 || | || 9 || 600 ||= F# || 17/12 or 24/17 || -3.000 +3.000 ||> 17/12 || | ||
|| 10 || 666.667 || 22/15 || +3.617 ||> 75/51 || | || 10 || 666.667 ||= **G** || 22/15 || +3.617 ||> 75/51 || | ||
|| 11 || 733.333 || 32/21 || +4.114 ||> 32/21 || | || 11 || 733.333 ||= Hb || 32/21 || +4.114 ||> 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 ||> 64/39 || | || 13 || 866.667 ||= **H** || 28/17 or 33/20 || +2.796 -0.293 ||> 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 ||> 16/9 || | || 15 || 1000 ||= Bb || 16/9 || +3.910 ||> 16/9 || | ||
|| 16 || 1066.667 || 50/27 || -0.096 ||> 39/21 || | || 16 || 1066.667 ||= A# || 50/27 || -0.096 ||> 39/21 || | ||
|| 17 || 1133.333 || 52/27 || -1.329 ||> 75/39 || | || 17 || 1133.333 ||= **B** || 52/27 || -1.329 ||> 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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<br /> | <br /> | ||
<!-- ws:start:WikiTextHeadingRule:2:&lt;h2&gt; --><h2 id="toc1"><a name="x18 Equal Divisions of the Octave-Basic Properties"></a><!-- ws:end:WikiTextHeadingRule:2 -->Basic Properties</h2> | <!-- ws:start:WikiTextHeadingRule:2:&lt;h2&gt; --><h2 id="toc1"><a name="x18 Equal Divisions of the Octave-Basic Properties"></a><!-- ws:end:WikiTextHeadingRule:2 -->Basic Properties</h2> | ||
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). <br /> | 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).<br /> | ||
<br /> | <br /> | ||
In order to access the excellent consonances actually available, one must take a considerably &quot;non-common-practice&quot; approach, meaning to avoid the usual closed-voice &quot;root-3rd-5th&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 <a class="wiki_link" href="/k%2AN%20subgroups">4*18 subgroup</a> <a class="wiki_link" href="/Just%20intonation%20subgroups">just intonation subgroup</a> 2.9.75.21.55.39.51. On this subgroup it tempers out exactly the same commas as 72 does on the full <a class="wiki_link" href="/17-limit">17-limit</a>, 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.<br /> | In order to access the excellent consonances actually available, one must take a considerably &quot;non-common-practice&quot; approach, meaning to avoid the usual closed-voice &quot;root-3rd-5th&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 <a class="wiki_link" href="/k%2AN%20subgroups">4*18 subgroup</a> <a class="wiki_link" href="/Just%20intonation%20subgroups">just intonation subgroup</a> 2.9.75.21.55.39.51. On this subgroup it tempers out exactly the same commas as 72 does on the full <a class="wiki_link" href="/17-limit">17-limit</a>, 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.<br /> | ||
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</td> | </td> | ||
<td>Cents<br /> | <td>Cents<br /> | ||
</td> | |||
<td style="text-align: center;">5L3s Notation<br /> | |||
</td> | </td> | ||
<td>Nearest Ratio<br /> | <td>Nearest Ratio<br /> | ||
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</td> | </td> | ||
<td>0<br /> | <td>0<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>C</strong><br /> | |||
</td> | </td> | ||
<td>1/1<br /> | <td>1/1<br /> | ||
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</td> | </td> | ||
<td>66.667<br /> | <td>66.667<br /> | ||
</td> | |||
<td style="text-align: center;">Db<br /> | |||
</td> | </td> | ||
<td>27/26<br /> | <td>27/26<br /> | ||
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</td> | </td> | ||
<td>133.333<br /> | <td>133.333<br /> | ||
</td> | |||
<td style="text-align: center;">C#<br /> | |||
</td> | </td> | ||
<td>27/25<br /> | <td>27/25<br /> | ||
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</td> | </td> | ||
<td>200<br /> | <td>200<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>D</strong><br /> | |||
</td> | </td> | ||
<td>9/8<br /> | <td>9/8<br /> | ||
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</td> | </td> | ||
<td>266.667<br /> | <td>266.667<br /> | ||
</td> | |||
<td style="text-align: center;">Eb<br /> | |||
</td> | </td> | ||
<td>7/6<br /> | <td>7/6<br /> | ||
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</td> | </td> | ||
<td>333.333<br /> | <td>333.333<br /> | ||
</td> | |||
<td style="text-align: center;">D#<br /> | |||
</td> | </td> | ||
<td>17/14 or 40/33<br /> | <td>17/14 or 40/33<br /> | ||
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</td> | </td> | ||
<td>400<br /> | <td>400<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>E</strong><br /> | |||
</td> | </td> | ||
<td>5/4 or 44/35<br /> | <td>5/4 or 44/35<br /> | ||
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</td> | </td> | ||
<td>466.667<br /> | <td>466.667<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>F</strong><br /> | |||
</td> | </td> | ||
<td>21/16<br /> | <td>21/16<br /> | ||
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</td> | </td> | ||
<td>533.333<br /> | <td>533.333<br /> | ||
</td> | |||
<td style="text-align: center;">Gb<br /> | |||
</td> | </td> | ||
<td>15/11<br /> | <td>15/11<br /> | ||
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</td> | </td> | ||
<td>600<br /> | <td>600<br /> | ||
</td> | |||
<td style="text-align: center;">F#<br /> | |||
</td> | </td> | ||
<td>17/12 or 24/17<br /> | <td>17/12 or 24/17<br /> | ||
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</td> | </td> | ||
<td>666.667<br /> | <td>666.667<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>G</strong><br /> | |||
</td> | </td> | ||
<td>22/15<br /> | <td>22/15<br /> | ||
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</td> | </td> | ||
<td>733.333<br /> | <td>733.333<br /> | ||
</td> | |||
<td style="text-align: center;">Hb<br /> | |||
</td> | </td> | ||
<td>32/21<br /> | <td>32/21<br /> | ||
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</td> | </td> | ||
<td>800<br /> | <td>800<br /> | ||
</td> | |||
<td style="text-align: center;">G#<br /> | |||
</td> | </td> | ||
<td>8/5 or 35/22<br /> | <td>8/5 or 35/22<br /> | ||
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</td> | </td> | ||
<td>866.667<br /> | <td>866.667<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>H</strong><br /> | |||
</td> | </td> | ||
<td>28/17 or 33/20<br /> | <td>28/17 or 33/20<br /> | ||
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</td> | </td> | ||
<td>933.333<br /> | <td>933.333<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>A</strong><br /> | |||
</td> | </td> | ||
<td>12/7<br /> | <td>12/7<br /> | ||
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</td> | </td> | ||
<td>1000<br /> | <td>1000<br /> | ||
</td> | |||
<td style="text-align: center;">Bb<br /> | |||
</td> | </td> | ||
<td>16/9<br /> | <td>16/9<br /> | ||
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</td> | </td> | ||
<td>1066.667<br /> | <td>1066.667<br /> | ||
</td> | |||
<td style="text-align: center;">A#<br /> | |||
</td> | </td> | ||
<td>50/27<br /> | <td>50/27<br /> | ||
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</td> | </td> | ||
<td>1133.333<br /> | <td>1133.333<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>B</strong><br /> | |||
</td> | </td> | ||
<td>52/27<br /> | <td>52/27<br /> | ||
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</td> | </td> | ||
<td>1200<br /> | <td>1200<br /> | ||
</td> | |||
<td style="text-align: center;"><strong>C</strong><br /> | |||
</td> | </td> | ||
<td>2/1<br /> | <td>2/1<br /> | ||