Würschmidt comma

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The Würschmidt comma ([17 1 -8 = 393216/390625) is a 5-limit comma of 11.4 cents.

Interval information
Ratio 393216/390625
Factorization 217 × 3 × 5-8
Monzo [17 1 -8
Size in cents 11.44529¢
Name Würschmidt comma
FJS name [math]\displaystyle{ \text{dddd3}_{5,5,5,5,5,5,5,5} }[/math]
Special properties reduced
Tenney norm (log2 nd) 37.1604
Weil norm (log2 max(n, d)) 37.1699
Wilson norm (sopfr(nd)) 77
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It is the amount by which eight major thirds fall short of a perfect fifth, octave-reduced: ((5/4)8 × 393216/390625) / 4 = 3/2.

Therefore, it is also the amount by which seven major thirds fall short of 24/5 (i.e. 6/5 plus two octaves). In other words, ((5/4)7 × 393216/390625) / 4 = 6/5.

Tempering it out leads to the würschmidt family of temperaments. As in meantone, it implies that 3/2 will be tempered flat and/or 5/4 will be tempered sharp, and therefore 6/5 will be tempered flat.

See also