540edo: Difference between revisions

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== Theory ==

Since 540 = 2 × 270 and 540 = 45 × 12, 540edo contains [[270edo]] and [[12edo]] as subsets, both being important [[zeta edo]]s. It is [[enfactoring|enfactored]] in the 13-limit, with the same tuning as 270edo, but it makes for a reasonable 17-, 19- and 23-limit system, and ~~perhaps~~ beyond. It is, however, no longer [[consistent]] in the [[15-odd-limit]], all because of [[15/13]] being 1.14 cents sharp of just.

Since 540 = 2 × 270 and 540 = 45 × 12, 540edo contains [[270edo]] and [[12edo]] as subsets, both being important [[zeta edo]]s. It is [[enfactoring|enfactored]] in the 13-limit, with the same tuning as 270edo, but it makes for a reasonable 17-, 19- and 23-limit system, and beyond. It is, however, no longer [[consistent]] in the [[15-odd-limit]], all because of [[15/13]] being 1.14 cents sharp of just.

The equal temperament [[tempering out|tempers out]] [[1156/1155]] and [[2601/2600]] in the 17-limit; [[1216/1215]], [[1331/1330]], [[1445/1444]] and [[1729/1728]] in the 19-limit; [[1105/1104]] and [[1496/1495]] in the 23-limit. Although it does quite well in these limits, it is not as ''efficient'' as 270edo's original mappings, as it has greater relative errors (→ [[#Regular temperament properties]]). It is therefore a question of whether one thinks these tuning improvements and differently supplied [[essentially tempered chord]]s are worth the load of all the extra notes.

The approximation to [[29/1|29]] and [[31/1|31]] are relatively weak, but [[37/1|37]], [[41/1|41]] and [[43/1|43]] are quite spot on, with the 43 coming from 270edo. For this reason, we may consider it as a full [[43-limit]] system. For all the primes starting with 29, it removes the distinction of otonal and utonal [[superparticular ratio|superparticular]] pairs (e.g. 29/28 vs 30/29 for prime 29) by tempering out the corresponding [[square superparticular]]s, which is responsible for its slightly flat-tending tuning profile. Prime [[47/1|47]] does not have that privilege and falls practically halfway between, though the sharp mapping might be preferred to keep [[47/46]] wider than [[48/47]]. As a compensation, you do get a spot-on prime [[53/1|53]] for free.

=== Prime harmonics ===

{{Harmonics in equal|540|columns=12|start=13|collapsed=true|title=Approximation of prime harmonics in 540edo (continued)}}

=== Subsets and supersets ===

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 == Theory ==
-Since 540 = 2 × 270 and 540 = 45 × 12, 540edo contains [[270edo]] and [[12edo]] as subsets, both being important [[zeta edo]]s. It is [[enfactoring|enfactored]] in the 13-limit, with the same tuning as 270edo, but it makes for a reasonable 17-, 19- and 23-limit system, and perhaps beyond. It is, however, no longer [[consistent]] in the [[15-odd-limit]], all because of [[15/13]] being 1.14 cents sharp of just.
+Since 540 = 2 × 270 and 540 = 45 × 12, 540edo contains [[270edo]] and [[12edo]] as subsets, both being important [[zeta edo]]s. It is [[enfactoring|enfactored]] in the 13-limit, with the same tuning as 270edo, but it makes for a reasonable 17-, 19- and 23-limit system, and beyond. It is, however, no longer [[consistent]] in the [[15-odd-limit]], all because of [[15/13]] being 1.14 cents sharp of just.
 The equal temperament [[tempering out|tempers out]] [[1156/1155]] and [[2601/2600]] in the 17-limit; [[1216/1215]], [[1331/1330]], [[1445/1444]] and [[1729/1728]] in the 19-limit; [[1105/1104]] and [[1496/1495]] in the 23-limit. Although it does quite well in these limits, it is not as ''efficient'' as 270edo's original mappings, as it has greater relative errors (→ [[#Regular temperament properties]]). It is therefore a question of whether one thinks these tuning improvements and differently supplied [[essentially tempered chord]]s are worth the load of all the extra notes.
+The approximation to [[29/1|29]] and [[31/1|31]] are relatively weak, but [[37/1|37]], [[41/1|41]] and [[43/1|43]] are quite spot on, with the 43 coming from 270edo. For this reason, we may consider it as a full [[43-limit]] system. For all the primes starting with 29, it removes the distinction of otonal and utonal [[superparticular ratio|superparticular]] pairs (e.g. 29/28 vs 30/29 for prime 29) by tempering out the corresponding [[square superparticular]]s, which is responsible for its slightly flat-tending tuning profile. Prime [[47/1|47]] does not have that privilege and falls practically halfway between, though the sharp mapping might be preferred to keep [[47/46]] wider than [[48/47]]. As a compensation, you do get a spot-on prime [[53/1|53]] for free.
 === Prime harmonics ===
-{{Harmonics in equal|540|columns=11}}
+{{Harmonics in equal|540|columns=12}}
+{{Harmonics in equal|540|columns=12|start=13|collapsed=true|title=Approximation of prime harmonics in 540edo (continued)}}
 === Subsets and supersets ===