Ploidacot/Alpha-dicot: Difference between revisions
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{{Breadcrumb}} | {{Breadcrumb}}{{Infobox ploidacot|Ploids=1|Shears=1|Cots=2|Pergen=[P8, P4/2]|Forms=5, 9, 14|Title=Alpha-dicot; omega-dicot}}'''Alpha-dicot''' is a temperament archetype where the generator is a [[Interseptimal interval|semitwelfth]], two of which make a perfect twelfth of [[3/1]], and the period is a [[2/1]] octave. Equivalently, the generator could be a semifourth, two of which make a [[4/3]], so '''omega-dicot''' means the same thing and is unused. | ||
Alpha-dicot temperaments usually generate the [[5L 4s]] MOS structure, named "semiquartal" after the semifourth generator, as well as the child scale [[5L 9s]]. Alpha-dicot temperaments tend to involve interseptimal intervals, which are in between conventional diatonic intervals. | |||
Alpha-dicot temperaments usually generate the [[5L 4s]] MOS structure, named "semiquartal" after the semifourth generator, | |||
== Intervals and notation == | == Intervals and notation == | ||
Alpha-dicot | Alpha-dicot notation is complicated as it conventionally requires either the introduction of new "[[hemipythagorean]]" ordinals or the use of scales other than the standard diatonic scale. As such, there is no universally accepted convention. Note and interval names are provided where alpha-dicot intervals align with standard monocot intervals (which use [[Chain-of-fifths notation]]). | ||
{| class="wikitable" | |||
|+Alpha-dicot intervals (assuming pure octave and fifth) | |||
|+ | |||
!# | !# | ||
!Cents | !Cents | ||
!Notation | !Notation | ||
!Name | !Name | ||
|- | |- | ||
| -9 | | -9 | ||
| | |1041.20 | ||
| | | | ||
| | | | ||
|- | |- | ||
| -8 | | -8 | ||
Line 31: | Line 23: | ||
|- | |- | ||
| -7 | | -7 | ||
| | |543.16 | ||
| | | | ||
| | | | ||
|- | |- | ||
| -6 | | -6 | ||
Line 41: | Line 33: | ||
|- | |- | ||
| -5 | | -5 | ||
| | |45.11 | ||
| | | | ||
| | | | ||
|- | |- | ||
| -4 | | -4 | ||
Line 51: | Line 43: | ||
|- | |- | ||
| -3 | | -3 | ||
| | |747.07 | ||
| | | | ||
| | | | ||
|- | |- | ||
| -2 | | -2 | ||
Line 61: | Line 53: | ||
|- | |- | ||
| -1 | | -1 | ||
| | |249.02 | ||
| | | | ||
| | | | ||
|- | |- | ||
|0 | |0 | ||
|0 | |0 | ||
|C | |C | ||
|perfect unison | |perfect unison | ||
|- | |- | ||
|1 | |1 | ||
| | |950.98 | ||
| | | | ||
| | | | ||
|- | |- | ||
|2 | |2 | ||
Line 81: | Line 73: | ||
|- | |- | ||
|3 | |3 | ||
| | |452.93 | ||
| | | | ||
| | | | ||
|- | |- | ||
|4 | |4 | ||
Line 91: | Line 83: | ||
|- | |- | ||
|5 | |5 | ||
| | |1154.89 | ||
| | | | ||
| | | | ||
|- | |- | ||
|6 | |6 | ||
Line 101: | Line 93: | ||
|- | |- | ||
|7 | |7 | ||
| | |656.84 | ||
| | | | ||
| | | | ||
|- | |- | ||
|8 | |8 | ||
Line 111: | Line 103: | ||
|- | |- | ||
|9 | |9 | ||
| | |158.8 | ||
| | | | ||
| | | | ||
|} | |} | ||
== Temperament interpretations == | == Temperament interpretations == | ||
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=== Bug === | === Bug === | ||
[[Bug]] is an exotemperament, equating the | [[Bug]] is an exotemperament, equating the semitwelfth generator to 5/3. This means that 9/5 is the same interval (tempering out [[27/25]]), and the semifourth represents both 6/5 and 10/9. This is clearly badly inaccurate, but is probably the best 5-limit interpretation of this ploidacot. | ||
The best tunings tend to be around 940{{c}} for the semitwelfth, with a somewhat flat twelfth. This sets the semifourth to 260{{c}}, which is close to [[7/6]]. | The best tunings tend to be around 940{{c}} for the semitwelfth, with a somewhat flat twelfth. This sets the semifourth to 260{{c}}, which is close to [[7/6]]. | ||
=== Semaphore === | === Semaphore === | ||
Given that bug sets the | Given that bug sets the semifourth close to 7/6, what happens if it is set equal to 7/6 in the 2.3.7 subgroup? Then, it is equated to [[8/7]], and [[49/48]] is tempered out. The semitwelfth is equated to [[12/7]] and [[7/4]]. This is still an inaccurate temperament, but is on the edge as to whether it counts as exo. | ||
The best tunings tend to be around 950{{c}} here, with a far more accurate twelfth. But, just like how bug's semifourth generator was close to 7/6, this is close to [[26/15]]. | The best tunings tend to be around 950{{c}} here, with a far more accurate twelfth. But, just like how bug's semifourth generator was close to 7/6, this is close to [[26/15]]. | ||
=== Barbados === | === Barbados === | ||
Here, the generator actually is 26/15, equated with [[45/26]]. This is | Here, the generator actually is 26/15, equated with [[45/26]]. This is an accurate temperament, tempering out the unnoticeable comma of [[676/675]], but it is defined in the awkward 2.3.13/5 subgroup. The semifourth here is [[15/13]][[~]][[52/45]]. | ||
As the comma is so small, the best tunings are close to just. The semitwelfth is around 951{{c}}, leading to a near-just twelfth. | As the comma is so small, the best tunings are close to just. The semitwelfth is around 951{{c}}, leading to a near-just twelfth. | ||
{{Todo| unify precision }} |