81/70

Interval information

Ratio

81/70

Factorization

2^-1 × 3⁴ × 5^-1 × 7^-1

Monzo

[-1 4 -1 -1⟩

Size in cents

252.6804¢

Names

septimal semiaugmented second,
septimal ultramajor second

Color name

rg2, rugu 2nd

FJS name

[math]\displaystyle{ \text{M2}_{5,7} }[/math]

Special properties

reduced

Tenney norm (log₂ nd)

12.4691

Weil norm (log₂ max(n, d))

12.6797

Wilson norm (sopfr(nd))

26

Open this interval in xen-calc

81/70, the septimal semiaugmented second or septimal ultramajor second is a 7-limit interseptimal ratio of about 253 cents. It is sharp of a subminor third 7/6 by a sensamagic comma 245/243, and sharp of a major second 16/9 by a septimal quartertone 36/35.

It is also sharp of a minor third 6/5 by a subminor second 28/27. For this fact it is useful in the Canovian chord and provides the function of a voice leading up to the minor third.

The interval is so perfectly approximated by 19-edo, with an error of 0.05 cents. There are a number of edos that do this equally well, 171-edo to name one. The first edo that does this better than 19-edo with patent val is 660-edo.

81/70

See also