128/81

Interval information

Ratio	128/81
Factorization	27 × 3-4
Monzo	[7 -4⟩
Size in cents	792.18¢
Names	Threerish minor sixth, Pythagorean minor sixth
Color name	sw6, sawa 6th
FJS name	[math]\displaystyle{ \text{m6} }[/math]
Special properties	reduced, reduced subharmonic
Tenney norm (log2 nd)	13.3399
Weil norm (log2 max(n, d))	14
Wilson norm (sopfr(nd))	26
[sound info]
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128/81 is the Pythagorean minor sixth, created by stacking four instances of 4/3 and octave-reducing. In contrast to the more typical 8/5—with which it is conflated in meantone—this interval has a harmonic entropy level roughly on par with that of 12/11. Thus, some would argue that it is functionally an imperfect dissonance.

See also

• 81/64 – Its octave complement
• Gallery of just intervals
• Pythagorean tuning