Würschmidt comma
The Würschmidt comma ([17 1 -8⟩ = 393216/390625) is a 5-limit comma of 11.4 cents.
| Interval information |
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. It is also equal to the difference between the lesser diesis and the magic comma, (128/125)/(3125/3072).
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.