3.5 subgroup: Difference between revisions

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The 3.5 subgroup is a [[retraction]] of the [[5-limit]], obtained by removing prime 2. Its simplest [[expansion]] is the [[3.5.7 subgroup]], which adds prime [[7/1|7]].

If used with tritave-equivalence, it is an infinite chain of stacking the classical major sixth [[5/3]] with tritave-reduction, analogous to how [[Pythagorean tuning]] (also known as the 2.3 subgroup or 3-limit) involves stacking [[2/1]] with octave-reduction. It can be regarded as an application of the [[Pythagorean ~~tuning]]~~ principle (~~the~~ stacking the smallest prime larger than the equave) to tritave-equivalence. The 3.5 subgroup is related to tritave-equivalent [[rank-2 ~~temperaments~~]] generated by ~[[5/3]], such as [[Arcturus]] and [[Delta Centauri]]. The famous rank 2 Bohlen-Pierce/sensamagic temperament, however, is generated by [[7/3]].

If used with [[3/1|tritave]]-equivalence, it is an infinite chain of stacking the classical major sixth [[5/3]] with tritave-reduction, analogous to how [[Pythagorean tuning]] (also known as the 2.3 subgroup or 3-limit) involves stacking [[3/2]] with octave-reduction. It can be regarded as an application of the Pythagorean principle (stacking the smallest prime harmonic larger than the [[equave]]) to tritave-equivalence. The 3.5 subgroup is related to tritave-equivalent [[rank-2 temperament]]s generated by ~[[5/3]], such as 3.5.7 [[Arcturus]] and 3.5.11 [[Delta Centauri]]. The famous rank 2 Bohlen-Pierce/sensamagic temperament, however, is generated by [[7/3]].

== MOS scales ==

As it is a [[rank-2]] system, stacking 5/3 with tritave-reduction can produce [[MOS scale]]s, just like how Pythagorean tuning famously produces one variation of pentatonic, diatonic and chromatic scales.

The non-trivial MOS scales that are produced are: [[2L 1s (3/1-equivalent)|2L 1s<3/1>]], [[2L 3s (3/1-equivalent)|2L 3s<3/1>]], [[2L 5s (3/1-equivalent))|2L 5s<3/1>]], [[2L 7s (3/1-equivalent)|2L 7s<3/1>]], [[2L 9s (3/1-equivalent)|2L 9s<3/1>]], [[2L 11s (3/1-equivalent)|2L 11s<3/1>]], [[13L 2s (3/1-equivalent)|13L 2s<3/1>]], [[15L 13s (3/1-equivalent)|15L 13s<3/1>]], [[28L 15s (3/1-equivalent)|28L 15s<3/1>]]. Probably the most practical scales are the 11-note (2L 9s), 13-note (2L 11s), and 15-note (13L 2s) scales. The reason for all of the 2L scales is because 5/3 (884 cents) is quite near √3 (951 cents) (incidentally, this fact is realized by the [[bug]] temperament, and removing octaves from bug results in [[2edt]] as a 3.5 equal temperament).

== Generator chain ==

{|class="wikitable"

|-

!Number of generators

!Interval

!Cents

|-

|0

|[[1/1]]

|0.000

|-

|1

|[[5/3]]

|884.359

|-

|2

|[[25/9]]

|1768.717

|-

|3

|[[125/81]]

|751.121

|-

|4

|[[625/343]]

|1635.480

|}

[[Category:Just intonation subgroups|#]]

[[Category:5-limit|#]]

@@ Line 3: / Line 3: @@
 The 3.5 subgroup is a [[retraction]] of the [[5-limit]], obtained by removing prime 2. Its simplest [[expansion]] is the [[3.5.7 subgroup]], which adds prime [[7/1|7]].
-If used with tritave-equivalence, it is an infinite chain of stacking the classical major sixth [[5/3]] with tritave-reduction, analogous to how [[Pythagorean tuning]] (also known as the 2.3 subgroup or 3-limit) involves stacking [[2/1]] with octave-reduction. It can be regarded as an application of the [[Pythagorean tuning]] principle (the stacking the smallest prime larger than the equave) to tritave-equivalence. The 3.5 subgroup is related to tritave-equivalent [[rank-2 temperaments]] generated by ~[[5/3]], such as [[Arcturus]] and [[Delta Centauri]]. The famous rank 2 Bohlen-Pierce/sensamagic temperament, however, is generated by [[7/3]].
+If used with [[3/1|tritave]]-equivalence, it is an infinite chain of stacking the classical major sixth [[5/3]] with tritave-reduction, analogous to how [[Pythagorean tuning]] (also known as the 2.3 subgroup or 3-limit) involves stacking [[3/2]] with octave-reduction. It can be regarded as an application of the Pythagorean principle (stacking the smallest prime harmonic larger than the [[equave]]) to tritave-equivalence. The 3.5 subgroup is related to tritave-equivalent [[rank-2 temperament]]s generated by ~[[5/3]], such as 3.5.7 [[Arcturus]] and 3.5.11 [[Delta Centauri]]. The famous rank 2 Bohlen-Pierce/sensamagic temperament, however, is generated by [[7/3]].
+== MOS scales ==
+As it is a [[rank-2]] system, stacking 5/3 with tritave-reduction can produce [[MOS scale]]s, just like how Pythagorean tuning famously produces one variation of pentatonic, diatonic and chromatic scales.
+The non-trivial MOS scales that are produced are: [[2L 1s (3/1-equivalent)|2L 1s<3/1>]], [[2L 3s (3/1-equivalent)|2L 3s<3/1>]], [[2L 5s (3/1-equivalent))|2L 5s<3/1>]], [[2L 7s (3/1-equivalent)|2L 7s<3/1>]], [[2L 9s (3/1-equivalent)|2L 9s<3/1>]], [[2L 11s (3/1-equivalent)|2L 11s<3/1>]], [[13L 2s (3/1-equivalent)|13L 2s<3/1>]], [[15L 13s (3/1-equivalent)|15L 13s<3/1>]], [[28L 15s (3/1-equivalent)|28L 15s<3/1>]]. Probably the most practical scales are the 11-note (2L 9s), 13-note (2L 11s), and 15-note (13L 2s) scales. The reason for all of the 2L scales is because 5/3 (884 cents) is quite near √3 (951 cents) (incidentally, this fact is realized by the [[bug]] temperament, and removing octaves from bug results in [[2edt]] as a 3.5 equal temperament).
+== Generator chain ==
+{|class="wikitable"
+|-
+!Number of generators
+!Interval
+!Cents
+|-
+|0
+|[[1/1]]
+|0.000
+|-
+|1
+|[[5/3]]
+|884.359
+|-
+|2
+|[[25/9]]
+|1768.717
+|-
+|3
+|[[125/81]]
+|751.121
+|-
+|4
+|[[625/343]]
+|1635.480
+|}
+[[Category:Just intonation subgroups|#]]
+[[Category:5-limit|#]]