245/243: Difference between revisions

Created page with "{{Infobox Interval | Ratio = 245/243 | Monzo = 0 -5 1 2 | Cents = 14.19052 | Name = Sensamagic comma | Color name = zzy2, zozoyo 2nd | Sound = }} '''245/243''', the '''sensa..."
 
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{{interwiki
| de = 245/243
| en = 245/243
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{{Infobox Interval
{{Infobox Interval
| Ratio = 245/243
| Name = sensamagic comma
| Monzo = 0 -5 1 2
| Color name = zzy2, zozoyo 2nd,<br>Zozoyo comma
| Cents = 14.19052
| Comma = yes
| Name = Sensamagic comma
| Color name = zzy2, zozoyo 2nd
| Sound =  
}}
}}
'''245/243''', the '''sensamagic comma''', is a [[small comma|small]] [[7-limit]] [[comma]] measuring 14.2 [[cent]]s. It is the amount by which two septimal major thirds ([[9/7]]) fall short of a classic major sixth ([[5/3]]), or the difference between [[28/27]] and [[36/35]].


'''245/243''', the '''sensamagic comma''' is a [[7-limit]] ratio of 14.2 cents. It is amount by which two septimal major thirds [[9/7]] fall short of a major sixth [[5/3]], or the difference between [[28/27]] and [[36/35]]. Tempering it out leads to [[sensamagic family]], where 5/3 is split into two equal parts, each representing 9/7~[[35/27]], and may be extended to represent higher-limit ratios like [[13/10]], [[22/17]], etc.
== Temperaments ==
[[Tempering out]] this comma alone in the 7-limit leads to the [[sensamagic]] temperament, where 5/3 is split into two equal parts, each representing 9/7~[[35/27]], and may be extended to represent higher-limit ratios like [[13/10]], [[22/17]], etc. It enables [[sensamagic chords]].
 
Tempering it out in the [[3.5.7 subgroup]] leads to the non-octave [[BPS]] temperament, which features a [[4L 5s (3/1-equivalent)|lambda scale]] as is found in [[13edt]], the [[Bohlen–Pierce scale]].
 
See [[Sensamagic family]] for the rank-3 temperament family where it is tempered out. See [[Sensamagic clan]] for the rank-2 clan where it is tempered out.
 
== Etymology ==
This comma was first named as ''octarod'' by [[Gene Ward Smith]] in 2005 as a contraction of ''[[octacot]]'' and ''[[rodan]]''<ref>[https://yahootuninggroupsultimatebackup.github.io/tuning-math/topicId_12900.html Yahoo! Tuning Group | ''Seven limit comma names from pairs of temperament names'']</ref>, and was renamed to ''sensamagic'' in 2010 as a concatenation of [[sensi]] and [[magic]]<ref>[https://yahootuninggroupsultimatebackup.github.io/tuning/topicId_88759.html Yahoo! Tuning Group | ''Some unnamed 7-limit temperaments'']</ref>.
 
<blockquote>
Here's a thought: 245/243 tells us that two 9/7['s] make up a 5/3. Hence, the temperaments which most exploit this and for which the comma is most characteristic are the ones where 9/7 has a low complexity. And this means sensi (complexity 1) and magic (complexity 2). So my proposal "sensamagic" is the way to go by this reasoning, which strikes me as pretty strong.
</blockquote>
 
—Gene Ward Smith
 
In 2025, [[Tristan Bay]] proposed ''lambda comma'' to reflect the fact that [[edt]]s which temper this comma out contain the aforementioned lambda scale (and is accurately tuned in the corresponding temperament, relative to the size of the edt).


== See also ==
== See also ==
* [[Gallery of just intervals]]


* [[Comma]]
== Notes ==
* [[Gallery of just intervals]]
<references />


[[Category:7-limit]]
[[Category:Interval]]
[[Category:Ratio]]
[[Category:Comma]]
[[Category:Sensamagic]]
[[Category:Sensamagic]]
[[Category:Bohlen–Pierce]]
[[Category:Commas named by combining multiple temperament names]]