Pentadacus: Difference between revisions

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| Subgroups = 5.7.11
| Subgroups = 5.7.11
| Comma basis = [[831875/823543]]
| Comma basis = [[831875/823543]]
| Edo join 1 = 43ed5 | Edo join 2 = 14ed5
| Edo join 1 = c14 | Edo join 2 = c43
| Mapping = 1; 3 7
| Mapping = 1; 3 7
| Generators = 55/49
| Generators = 55/49
| Generators tuning = 194.820
| Generators tuning = 194.8
| Optimization method = CWE
| Optimization method = CWE
| MOS scales = [[1L 12s (5/1-equivalent)|1L 12s<5/1>]], [[1L 13s (5/1-equivalent)|1L 13s<5/1>]], [[14L 1s (5/1-equivalent)|14L 1s<5/1>]], [[14L 15s (5/1-equivalent)|14L 15s<5/1>]]
| MOS scales = [[1L 12s (5/1-equivalent)|1L 12s<5/1>]], [[1L 13s (5/1-equivalent)|1L 13s<5/1>]], [[14L 1s (5/1-equivalent)|14L 1s<5/1>]], [[14L 15s (5/1-equivalent)|14L 15s<5/1>]]
| Color name =  
| Odd limit 1 = ? | Mistuning 1 = ? | Complexity 1 = ?
}}
}}


'''Pentadacus''' is a [[nonoctave]] [[regular temperament]] in the 5.7.11 [[subgroup]] which tempers out the comma [[831875/823543]]. It is even more exotic than [[Bohlen-Pierce]], lacking both [[2/1]] and [[3/1]], and typically it would be used with an [[equave]] of [[5/1]], also known as the pentave. It is generated by a [[meantone]]-esque small whole tone interval that represents [[54/49]]. Stacking 3 of these tones gives [[7/5]] and 7 of them give [[11/5]]. It was first discovered and named by [[User:CompactStar|CompactStar]] in 2026.
'''Pentadacus''' is a [[nonoctave]] [[regular temperament]] in the 5.7.11 [[subgroup]] which tempers out the comma [[831875/823543]]. It is even more exotic than [[Bohlen-Pierce]], lacking both [[2/1]] and [[3/1]], and typically it would be used with an [[equave]] of [[5/1]], also known as the pentave. It is generated by a [[meantone]]-esque small whole tone interval that represents [[54/49]]. Stacking 3 of these tones gives [[7/5]] and 7 of them give [[11/5]]. Properly-tuned pentadacus generates the [[5/1]]-equivalent [[mos scales]] [[1L 1s (5/1-equivalent)|1L 1s<5/1>]], [[1L 2s (5/1-equivalent)|1L 2s<5/1>]], etc. until ending the monolarge mos chain at [[1L 13s (5/1-equivalent)|1L 13s<5/1>]], followed by [[14L 1s (5/1-equivalent)|14L 1s<5/1>]], [[14L 15s (5/1-equivalent)|14L 15s<5/1>]]. Pentadacus has both low [[complexity]] (especially by the standards of the 5/1-equivalent world, where scales have lots of notes) and low [[error]] if tuned correctly, providing an [[efficiency|efficient]] traversal of the 5.7.11 subgroup. It was first discovered and named by [[User:CompactStar|CompactStar]] in 2026.


[[14ed5]] is an inaccurate but important tuning of Pentadacus, because in 14ed5, the whole tone generator corresponds to a single step of 14ed5, although the whole tone is bigger than usual being around [[9/8]]-sized, causing the approximations of 7/5 and 11/5 to be bad. Basically, pentadacus can be thought of as a compressed 14ed5, at least until you hit [[5/1]]. 14ed5 is also close to [[6edo]], the familiar whole-tone scale with octaves, and 6 generators in pentadacus can sound like a tempered octave but it’s usually quite inaccurate and dissonant. Properly-tuned Pentadacus generates the [[5/1]]-equivalent [[MOS scales]] [[1L 1s (5/1-equivalent)|1L 1s<5/1>]], [[1L 2s (5/1-equivalent)|1L 2s<5/1>]], etc. until ending the monolarge MOS chain at [[1L 13s (5/1-equivalent)|1L 13s<5/1>]], followed by [[14L 1s (5/1-equivalent)|14L 1s<5/1>]], [[14L 15s (5/1-equivalent)|14L 15s<5/1>]]. After this it branches into.
Pentadacus can be thought of as a compressed [[14ed5]] until you hit [[5/1]], as is best exemplified by the [[1L 13s (5/1-equivalent)|1L 13s<5/1>]] Pentadacus[14] mos. Because of this, many good smaller pentadacus tunings are of the form (14''n'' + 1)ed5 such as [[29ed5]], [[43ed5]], and [[57ed5]]. In this respect, it is similar to a [[cluster temperament]], but does not seem to exactly meet the definition of a cluster temperament. 14ed5 is also close to [[6edo]], the familiar whole-tone scale with octaves, so pentadacus is very alien (being a step above even tritave-equivalent temperaments) but can lapse into sounding like the familiar whole-tone scale at times. 6 generators in pentadacus can sound a bit like a [[stretched and compressed tuning|compressed octave]] but it is usually inaccurate unless you are using a very sharp tuning like 14ed5.


Pentadacus has both low [[complexity]] (especially by the standards of the 5/1-equivalent world, where scales have lots of notes) and low [[error]] if tuned correctly, providing an [[efficiency|efficient]] traversal of the 5.7.11 subgroup. In that respect it's vaguely similar to [[meantone]] in the 5-limit and [[Bohlen-Pierce-Stearns]] in the 3.5.7 subgroup, but it also differs  because of the proximity of its generator to a step of 14ed5, while the generators of meantone and BPS are not similar to the step size of any non-trivial EDO or EDT.
Pentadacus is connected to the octave-repeating [[didacus]] temperament as both have a small whole tone generator for which 3 stack to 7/5, and [[didacus|undecimal didacus]] can actually be viewed not only as an extension of didacus to include the 11th harmonic, but also an extension of pentadacus to include octaves. Pentadacus's connection to [[14ed5]] (which is effectively 6edo with a just 5/1) is a lot like didacus's connection to [[6edo]].


Pentadacus is connected to the octave-repeating [[didacus]] temperament as both have a small whole tone generator for which 3 stack to 7/5, and [[undecimal didacus]] can actually be viewed not only as an extension of didacus to include the 11th harmonic, but also an extension of pentadacus to include octaves.
== Interval chain ==
{{Todo|inline=1|complete table}}


{| class="wikitable center-1 right-2"
! # !! Cents* !! Approximate ratios
|-
| 0 || 0.0 || '''1/1'''
|}


[[Category:Pentadacus| ]] <!-- main article -->
[[Category:Rank-2 temperaments]]
[[Category:Rank-2 temperaments]]
[[Category:Didacus]]
[[Category:Subgroup temperaments]]

Latest revision as of 08:49, 8 March 2026

Pentadacus
Subgroups 5.7.11
Comma basis 831875/823543
Reduced mapping ⟨1; 3 7]
ET join c14 & c43
Generators (CWE) ~55/49 = 194.8 ¢
MOS scales 1L 12s<5/1>, 1L 13s<5/1>, 14L 1s<5/1>, 14L 15s<5/1>
Ploidacot tri7cleft
Minimax error ?-integer-limit: ? ¢
Target scale size ?-integer-limit: ? notes

Pentadacus is a nonoctave regular temperament in the 5.7.11 subgroup which tempers out the comma 831875/823543. It is even more exotic than Bohlen-Pierce, lacking both 2/1 and 3/1, and typically it would be used with an equave of 5/1, also known as the pentave. It is generated by a meantone-esque small whole tone interval that represents 54/49. Stacking 3 of these tones gives 7/5 and 7 of them give 11/5. Properly-tuned pentadacus generates the 5/1-equivalent mos scales 1L 1s<5/1>, 1L 2s<5/1>, etc. until ending the monolarge mos chain at 1L 13s<5/1>, followed by 14L 1s<5/1>, 14L 15s<5/1>. Pentadacus has both low complexity (especially by the standards of the 5/1-equivalent world, where scales have lots of notes) and low error if tuned correctly, providing an efficient traversal of the 5.7.11 subgroup. It was first discovered and named by CompactStar in 2026.

Pentadacus can be thought of as a compressed 14ed5 until you hit 5/1, as is best exemplified by the 1L 13s<5/1> Pentadacus[14] mos. Because of this, many good smaller pentadacus tunings are of the form (14n + 1)ed5 such as 29ed5, 43ed5, and 57ed5. In this respect, it is similar to a cluster temperament, but does not seem to exactly meet the definition of a cluster temperament. 14ed5 is also close to 6edo, the familiar whole-tone scale with octaves, so pentadacus is very alien (being a step above even tritave-equivalent temperaments) but can lapse into sounding like the familiar whole-tone scale at times. 6 generators in pentadacus can sound a bit like a compressed octave but it is usually inaccurate unless you are using a very sharp tuning like 14ed5.

Pentadacus is connected to the octave-repeating didacus temperament as both have a small whole tone generator for which 3 stack to 7/5, and undecimal didacus can actually be viewed not only as an extension of didacus to include the 11th harmonic, but also an extension of pentadacus to include octaves. Pentadacus's connection to 14ed5 (which is effectively 6edo with a just 5/1) is a lot like didacus's connection to 6edo.

Interval chain

Todo: complete table
# Cents* Approximate ratios
0 0.0 1/1