686/675: Difference between revisions

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{{Infobox Interval
{{Infobox Interval
| Ratio = 686/675
| Name = sengic comma, senga
| Monzo = 1 -3 -2 3
| Color name = z<sup>3</sup>gg3, Trizo-agugu comma
| Cents = 27.98529
| Comma = yes
| Name = sengic comma, <br>senga comma
| Color name = z<sup>3</sup>gg3, trizo-agugu 3rd, z3gg3 3rd
| FJS name = dd3<sup>7, 7, 7</sup><sub>25</sub>
| Sound =  
}}
}}
'''686/675''', the '''senga''' or '''sengic comma''', is a [[small comma|small]] [[7-limit]] [[comma]] measuring about 28.0 [[cent]]s. It pops up as the difference between [[7/6]] and a stack of two [[15/14]]'s, or the difference between [[5/4]] and a stack of three 15/14's. Besides, it is the difference between the septimal minor second, [[28/27]], and the jubilisma, [[50/49]].


The interval of '''686/675''', the '''senga comma''' or '''sengic comma''' is a [[7-limit]] [[small comma]]. It pops up as the difference between a stack of three [[7/6]]s and a stack of two [[5/4]]s. It is tempered out in temperaments of the [[sengic family]].
It factors into simpler commas as ([[126/125]])⋅([[245/243]]), the stack of the two simplest commas to define the 7-limit [[sensi]] temperament. In the [[2.3.5.7.13 subgroup]], it factors into ([[91/90]])⋅([[196/195]]), which equals ([[169/168]])⋅(196/195)<sup>2</sup> in turn, making it a [[lopsided comma]] with [[S-expression]] S13⋅S14<sup>2</sup>.
 
== Temperaments ==
[[Tempering out]] this comma in the 7-limit leads to the rank-3 [[sengic]] temperament. Rank-2 temperaments tempering out this comma include [[sensi]], [[negri]] and [[liese]]. Tempering out this comma in the 3/2.5/4.7/4 fractional subgroup gives the [[ambulatory]] temperament.
 
See [[Sengic family]] for the family of rank-3 temperaments where it is tempered out. See [[Sengic temperaments]] for the collection of rank-2 temperaments where it is tempered out.
 
== Etymology ==
The name ''senga'' was given by [[Gene Ward Smith]] in 2005. It is a contraction of ''[[sensi]]'' and ''gawel'', although ''gawel'' was later renamed to ''[[liese]]''<ref>[https://yahootuninggroupsultimatebackup.github.io/tuning-math/topicId_12900.html Yahoo! Tuning Group | ''Seven limit comma names from pairs of temperament names'']</ref>.  
 
== References ==
<references/>


[[Category:7-limit]]
[[Category:Small comma]]
[[Category:Sengic]]
[[Category:Sengic]]
[[Category:Commas named by combining multiple temperament names]]

Latest revision as of 10:22, 8 August 2026

Interval information
Ratio 686/675
Factorization 2 × 3-3 × 5-2 × 73
Monzo [1 -3 -2 3
Size in cents 27.98529¢
Names sengic comma,
senga
Color name z3gg3, Trizo-agugu comma
FJS name [math]\displaystyle{ \text{dd3}^{7,7,7}_{5,5} }[/math]
Special properties reduced
Tenney norm (log2 nd) 18.8208
Weil norm (log2 max(n, d)) 18.8441
Wilson norm (sopfr(nd)) 42
Comma size small
S-expression S13⋅S142
Open this interval in xen-calc

686/675, the senga or sengic comma, is a small 7-limit comma measuring about 28.0 cents. It pops up as the difference between 7/6 and a stack of two 15/14's, or the difference between 5/4 and a stack of three 15/14's. Besides, it is the difference between the septimal minor second, 28/27, and the jubilisma, 50/49.

It factors into simpler commas as (126/125)⋅(245/243), the stack of the two simplest commas to define the 7-limit sensi temperament. In the 2.3.5.7.13 subgroup, it factors into (91/90)⋅(196/195), which equals (169/168)⋅(196/195)2 in turn, making it a lopsided comma with S-expression S13⋅S142.

Temperaments

Tempering out this comma in the 7-limit leads to the rank-3 sengic temperament. Rank-2 temperaments tempering out this comma include sensi, negri and liese. Tempering out this comma in the 3/2.5/4.7/4 fractional subgroup gives the ambulatory temperament.

See Sengic family for the family of rank-3 temperaments where it is tempered out. See Sengic temperaments for the collection of rank-2 temperaments where it is tempered out.

Etymology

The name senga was given by Gene Ward Smith in 2005. It is a contraction of sensi and gawel, although gawel was later renamed to liese[1].

References