In music , the septimal semicomma , a seven -limit semicomma , is the ratio 126/125 and is equal to approximately 13.79 cents (play ⓘ [citation needed It is also called the small septimal comma [ 1] starling comma after its use in starling temperament .
Factored into primes it is:
2
∗ ∗ -->
3
2
∗ ∗ -->
5
− − -->
3
∗ ∗ -->
7
{\displaystyle 2*3^{2}*5^{-3}*7}
Or as simple just intervals:
(
6
/
5
)
3
∗ ∗ -->
(
7
/
6
)
∗ ∗ -->
(
2
/
1
)
− − -->
1
{\displaystyle (6/5)^{3}*(7/6)*(2/1)^{-1}}
Thus it is the difference between three minor thirds of 6/5 plus a septimal minor third of 7/6 and an octave (2/1). This comma is important to certain tuning systems, such as septimal meantone temperament .
A diminished seventh chord consisting of three minor thirds and a subminor third making up an octave is possible in such systems. This characteristic feature of these tuning systems is known as the septimal semicomma diminished seventh chord .
In equal temperament
It is tempered out in 19 equal temperament and 31 equal temperament , but not in 22 equal temperament , 34 equal temperament , 41 equal temperament , or 53 equal temperament .
References
Twelve-
(Numbers in bracketssemitones in the
Other
Other
Groups Semitones Quarter tones Commas Measurement Others
