Tetracot family: Difference between revisions
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{{Technical data page}} | {{Technical data page}} | ||
The parent of the '''tetracot family''' is [[tetracot]], the 5-limit | The parent of the '''tetracot family''' is [[tetracot]], the [[5-limit]] [[regular temperament|temperament]] [[tempering out]] the [[tetracot comma]] ([[ratio]]: 20000/19683, {{monzo|legend=1| 5 -9 4 }}). | ||
== Tetracot == | == Tetracot == | ||
{{Main| Tetracot }} | {{Main| Tetracot }} | ||
The [[generator]] of tetracot is [[~]][[10/9]], and that four of these give [[~]][[3/2]]. In fact, (10/9)<sup>4</sup> = (20000/19683)⋅(3/2). We also have (10/9)<sup>9</sup> = (20000/19683)<sup>2</sup>⋅(5/2). From this it is evident we should flatten the generator a bit, and [[34edo]] does this and makes for a recommendable tuning. Another possibility is to use (5/2)<sup>1/9</sup> for a generator. The 13-note [[mos]] gives enough space for eight triads, with the 20-note mos supplying many more. | |||
The name comes from members of the Araucaria family of conifers, which have four cotyledons (though sometimes these are fused). | |||
[[Subgroup]]: 2.3.5 | [[Subgroup]]: 2.3.5 | ||
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=== Overview to extensions === | === Overview to extensions === | ||
The second comma of the [[ | The second comma of the [[normal forms|normal comma list]] defines which 7-limit family member we are looking at. | ||
* [[875/864]], the keema, gives monkey; | * [[875/864]], the keema, gives monkey; | ||
* 179200/177147 (or equivalently [[225/224]]) gives bunya; | * 179200/177147 (or equivalently [[225/224]]) gives bunya; | ||
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==== Monkey and bunya ==== | ==== Monkey and bunya ==== | ||
Monkey tempers out the keema. The keema, 875/864, is the amount by which three just minor thirds fall short of 7/4, and tells us the ~7/4 of monkey is reached by three minor thirds in succession. It can be described as the {{nowrap| 34 & 41 }} temperament. [[41edo]] is an excellent tuning for monkey, and has the effect of making monkey identical to bunya with the same tuning. | |||
Bunya adds 225/224 to the list of commas and may be described as the {{nowrap| 34d & 41 }} temperament. 41edo can again be used as a tuning, in which case it is the same as monkey. However an excellent alternative is 14<sup>1/26</sup> as a generator, giving just ~7's and an improved value for ~5, at the cost of a slightly sharper, but still less than a cent sharp, fifth. Octave stretching, if employed, also serves to distinguish bunya from monkey, as its octaves should be stretched considerably less. | |||
Since the generator in all cases is between 10/9 and 11/10, it is natural to extend these temperaments to the 11-limit by tempering out (10/9)/(11/10) = [[100/99]]. This gives 11-limit monkey and 11-limit bunya. Again, 41edo can be used as a tuning, making the two identical, which is also the case if we turn to the 2.3.5.11 subgroup temperament, dispensing with 7. However, 11-limit bunya, like 7-limit bunya, profits a little from a slightly sharper fifth, such as the 14<sup>1/26</sup> generator supplies, or even sharper yet, as for instance by the val {{val| 355 563 823 997 1230 }}, with a 52/355 generator. | Since the generator in all cases is between 10/9 and 11/10, it is natural to extend these temperaments to the 11-limit by tempering out (10/9)/(11/10) = [[100/99]]. This gives 11-limit monkey and 11-limit bunya. Again, 41edo can be used as a tuning, making the two identical, which is also the case if we turn to the 2.3.5.11 subgroup temperament, dispensing with 7. However, 11-limit bunya, like 7-limit bunya, profits a little from a slightly sharper fifth, such as the 14<sup>1/26</sup> generator supplies, or even sharper yet, as for instance by the val {{val| 355 563 823 997 1230 }}, with a 52/355 generator. | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~10/9 = 176.818 | * CTE: ~2 = 1\1, ~10/9 = 176.818 | ||
* POTE:~2 = 1\1, ~10/9 = 177.203 | * POTE: ~2 = 1\1, ~10/9 = 177.203 | ||
{{Optimal ET sequence|legend=1| 7, 20c, 27, 34d, 61d, 95dd }} | {{Optimal ET sequence|legend=1| 7, 20c, 27, 34d, 61d, 95dd }} | ||
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{{See also| Chords of octacot }} | {{See also| Chords of octacot }} | ||
Octacot cuts the Gordian knot of deciding between the monkey and bunya mappings for 7 by cutting the generator in half and splitting the difference. It adds [[245/243]] to the normal comma list, and also tempers out [[2401/2400]]. It may also be described as 41 & | Octacot cuts the Gordian knot of deciding between the monkey and bunya mappings for 7 by cutting the generator in half and splitting the difference. It adds [[245/243]] to the normal comma list, and also tempers out [[2401/2400]]. It may also be described as {{nowrap| 41 & 68 }}. [[68edo]] or [[109edo]] can be used as tunings, as can (5/2)<sup>1/18</sup>, which gives just major thirds. Another tuning is [[150edo]], which has a generator, 11\150, of exactly 88 cents. This relates octacot to the [[88cET]] non-octave temperament, which like [[Carlos Alpha]] arguably makes more sense viewed as part of a rank-2 temperament with octaves rather than rank-1 without them. | ||
Once again and for the same reasons, it is natural to add 100/99 and 325/324 to the list of commas. Generators of 3\41, 8\109 and 11\150 (88 cents) are all good choices for the 7, 11 and 13 limits. | Once again and for the same reasons, it is natural to add 100/99 and 325/324 to the list of commas. Generators of 3\41, 8\109 and 11\150 (88 cents) are all good choices for the 7, 11 and 13 limits. | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~21/20 = 88.023 | * CTE: ~2 = 1\1, ~21/20 = 88.023 | ||
* POTE:~2 = 1\1, ~21/20 = 88.076 | * POTE: ~2 = 1\1, ~21/20 = 88.076 | ||
{{Optimal ET sequence|legend=1| 14c, 27, 41, 68, 109, 150, 259, 409bc, 668bbcc }} | {{Optimal ET sequence|legend=1| 14c, 27, 41, 68, 109, 150, 259, 409bc, 668bbcc }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~21/20 = 87.910 | * CTE: ~2 = 1\1, ~21/20 = 87.910 | ||
* POTE ~2 = 1\1, ~21/20 = 87.975 | * POTE: ~2 = 1\1, ~21/20 = 87.975 | ||
Optimal ET sequence: {{Optimal ET sequence| 14c, 27e, 41, 150ee, 191ee, 232cee }} | Optimal ET sequence: {{Optimal ET sequence| 14c, 27e, 41, 150ee, 191ee, 232cee }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~21/20 = 87.926 | * CTE: ~2 = 1\1, ~21/20 = 87.926 | ||
* POTE ~2 = 1\1, ~21/20 = 88.106 | * POTE: ~2 = 1\1, ~21/20 = 88.106 | ||
Optimal ET sequence: {{Optimal ET sequence| 14c, 27e, 41, 150eef, 191eeff, 232ceeff }} | Optimal ET sequence: {{Optimal ET sequence| 14c, 27e, 41, 150eef, 191eeff, 232ceeff }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~18/17 = 87.842 | * CTE: ~2 = 1\1, ~18/17 = 87.842 | ||
* POTE ~2 = 1\1, ~18/17 = 88.102 | * POTE: ~2 = 1\1, ~18/17 = 88.102 | ||
Optimal ET sequence: {{Optimal ET sequence| 14c, 27eg, 41 }} | Optimal ET sequence: {{Optimal ET sequence| 14c, 27eg, 41 }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~18/17 = 87.866 | * CTE: ~2 = 1\1, ~18/17 = 87.866 | ||
* POTE ~2 = 1\1, ~18/17 = 88.111 | * POTE: ~2 = 1\1, ~18/17 = 88.111 | ||
Optimal ET sequence: {{Optimal ET sequence| 14c, 27eg, 41 }} | Optimal ET sequence: {{Optimal ET sequence| 14c, 27eg, 41 }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~21/20 = 88.090 | * CTE: ~2 = 1\1, ~21/20 = 88.090 | ||
* POTE ~2 = 1\1, ~21/20 = 88.179 | * POTE: ~2 = 1\1, ~21/20 = 88.179 | ||
Optimal ET sequence: {{Optimal ET sequence| 14cf, 27e, 41f, 68ef, 109eff }} | Optimal ET sequence: {{Optimal ET sequence| 14cf, 27e, 41f, 68ef, 109eff }} | ||
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=== Devisemi (2.3.5.7.19) === | === Devisemi (2.3.5.7.19) === | ||
==== 2.3.5.19 subgroup ==== | ==== 2.3.5.19 subgroup ==== | ||
Subgroup: 2.3.5.19 | Subgroup: 2.3.5.19 | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~28/27 = 58.648 | * CTE: ~2 = 1\1, ~28/27 = 58.648 | ||
* POTE:~2 = 1\1, ~28/27 = 58.675 | * POTE: ~2 = 1\1, ~28/27 = 58.675 | ||
{{Optimal ET sequence|legend=1| 41, 143d, 184, 225, 266c }} | {{Optimal ET sequence|legend=1| 41, 143d, 184, 225, 266c }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~28/27 = 58.602 | * CTE: ~2 = 1\1, ~28/27 = 58.602 | ||
* POTE ~2 = 1\1, ~28/27 = 58.665 | * POTE: ~2 = 1\1, ~28/27 = 58.665 | ||
Optimal ET sequence: {{Optimal ET sequence| 20cde, 41 }} | Optimal ET sequence: {{Optimal ET sequence| 20cde, 41 }} | ||
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Optimal tunings: | Optimal tunings: | ||
* CTE: ~2 = 1\1, ~27/26 = 58.551 | * CTE: ~2 = 1\1, ~27/26 = 58.551 | ||
* POTE ~2 = 1\1, ~27/26 = 58.639 | * POTE: ~2 = 1\1, ~27/26 = 58.639 | ||
Optimal ET sequence: {{Optimal ET sequence| 20cdef, 21cdef, 41 }} | Optimal ET sequence: {{Optimal ET sequence| 20cdef, 21cdef, 41 }} | ||
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== Byhearted == | == Byhearted == | ||
{{See also| No-fives subgroup temperaments #Byhearted }} | |||
[[Subgroup]]: 2.3.5.7 | [[Subgroup]]: 2.3.5.7 | ||
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{{Mapping|legend=1| 2 2 2 3 | 0 4 9 9 }} | {{Mapping|legend=1| 2 2 2 3 | 0 4 9 9 }} | ||
: mapping generators: ~7/5, ~10/9 | |||
: | |||
Optimal tuning (CTE): ~7/5 = 1\2, ~10/9 = 175.472 | Optimal tuning (CTE): ~7/5 = 1\2, ~10/9 = 175.472 | ||