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| == Temperaments == | | == Temperaments == |
| Tempering out this comma alone in the 7-limit leads to the [[marvel]] temperament, which enables [[marvel chords]]. See [[marvel family]] for the family of rank-3 temperaments where it is tempered out. See [[marvel temperaments]] for a collection of rank-2 temperaments where it is tempered out. | | Tempering out this comma alone in the 7-limit leads to the [[marvel]] temperament, which enables [[marvel chords]]. See [[marvel family]] for the family of rank-3 temperaments where it is tempered out. See [[marvel temperaments]] for a collection of rank-2 temperaments where it is tempered out. |
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| === Canonical extensions of note ===
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| The marvel extension [[hecate]] has the no-17's [[19-limit]] as its subgroup, and [[undecimal marvel]] (aka unimarv), the extension chosen by [[Gene Ward Smith]], can be extended to the 13-limit. They merge in the rank 2 temperament [[catakleismic]] (which can be conceptualized as accepting both rank 3 marvel structures simultaneously), for which the smallest reasonable edo tuning for the full no-17's 19-limit is [[53edo]] followed by [[72edo]], though in 53edo the 11 and 19 are a little off and in 72edo the 13 and 19 are a little off instead; 72edo is positioned better as a full [[17-limit]] marvel system while 53edo is positioned better as a (potentially no-11's) [[13-limit]] marvel system. If we focus on the 11-limit of undecimal marvel (discarding the mapping of 13), [[31edo]] and [[41edo]] are the smallest to clearly succeed, though many accept 41edo's mapping of [[~]][[13/8]] to the neutral sixth and some accept that mapping for 31edo as contextually usable too.
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| === [[53edo]] and [[84edo]] tunings of 7-limit marvel ===
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| [[53edo]] and [[84edo]] are the smallest [[edo]]s to tune the supermajor second [[~]][[8/7]] flat (towards [[~]][[256/225]]), the subminor third [[~]][[7/6]] sharp (towards [[~]][[75/64]]), the supermajor third [[~]][[9/7]] flat (towards [[~]][[32/25]]) and the tritone [[~]][[7/5]] sharp (towards [[~]][[45/32]]), such that every [[7-limit]] [[9-odd-limit]] interval is tuned between itself and the [[5-limit]] interpretation it's separated from by [[225/224]], though even if you allow overtempering, the only smaller edo to satisfy all of these constraints is [[12edo]], which is a trivial tuning of it (meaning it is very high-damage owing to conflating many intervals so that the lattice is oversimplified). [[TE]], [[CTE]], [[CEE]] and [[CWE]] as well as the idea of tempering between pairs of 5- and 7-limit intervals separated by 225/224 all implicate these tuning tendencies of these 7-limit [[LCJI]] intervals for optimized 7-limit marvel tunings. Interestingly, [[72edo]] fails some of these constraints and is less optimized for others, in the sense that 53edo tunes closer to the more complex [[5-limit]] interpretations (which arguably need more tuning fidelity), which is something not taken into account by these tuning optimization schemes (so that they generally tune closer to [[LCJI]]). By contrast, [[84edo]], an overlooked superset of [[12edo]], has the benefit of being a high-limit performer in odd-limits 23 through 51 (inclusive). In fact, 53edo and 84edo are the '''only''' edos to satisfy all these constraints consistently when we include not overtempering to overshoot the 5-limit interval, and if we also require [[28/27]] to be sharp and [[25/24]] to be flat, 53edo is the only one, making it a uniquely optimized 7-limit marvel tuning; as far as the 9-odd-limit is concerned, the only intervals which are more than 25% off in 53edo are [[7/5]] and [[10/7]]], so that it is almost [[consistent to distance]] 2, and many more complex intervals of the 7-limit are [[consistent]] as well (barring the stacking of prime 7 more than once, so that 5 * 7 = 35 is fine but not 7 * 7 = 49, which causes inconsistencies in the 7-limited [[tonality diamond]]).
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| == Approximation == | | == Approximation == |
Revision as of 08:51, 15 January 2025
The interval of 225/224, the septimal kleisma or marvel comma is a 7-limit superparticular ratio. It pops up as the difference between pairs of 7-limit ratios, for example as (15/14)/(16/15) or (45/32)/(7/5).
Another useful relation is as the difference between the 25/24, the classical chromatic semitone, and 28/27, the septimal third-tone. Hence, it is also the difference between 32/25 and 9/7, and between 75/64 and 7/6.
In terms of commas, it is the difference between 81/80 and 126/125 and is tempered out alongside these two commas in septimal meantone. In the 11-limit it factors neatly into (385/384)(540/539), and in the 13-limit, (351/350)(625/624) or (325/324)(729/728).
Temperaments
Tempering out this comma alone in the 7-limit leads to the marvel temperament, which enables marvel chords. See marvel family for the family of rank-3 temperaments where it is tempered out. See marvel temperaments for a collection of rank-2 temperaments where it is tempered out.
Approximation
If we do not temper out this interval and instead repeatedly stack (and octave-reduce) it, we almost return to the starting point at the 311th step, meaning 311edo is a consistent circle of 225/224's. Note that this is not true for 226/225 or 224/223, the adjacent superparticulars, as they accumulate too much error to close into a circle in 311edo.
Etymology
Marvel comma was named after the corresponding temperament, marvel, which was named by Gene Ward Smith in 2002–2003.
See also
