5120/5103
| Interval information |
5/7-kleisma,
aberschisma
Saruyo comma
(Shannon, [math]\sqrt{nd}[/math])
5120/5103, the hemifamity comma, 5/7-kleisma, or aberschisma, is a small 7-limit comma measuring about 5.8 ¢. It is the difference between 7/5 (small septimal tritone) and 1024/729 (Pythagorean diminished fifth), or between 10/7 (large septimal tritone) and 729/512 (Pythagorean augmented fourth). It is also the difference between 15/14 and 2187/2048, between 21/20 and 256/243, between 80/63 and 81/64, etc., hence, between the septimal comma of 64/63 and the syntonic comma of 81/80, as well as between 32805/32768, the schisma, and 225/224, the marvel comma.
Temperaments
Tempering it out leads to the rank-3 hemifamity temperament, which splits the septimal quartertone 36/35 into two equal parts, each representing 81/80~64/63. Rank-2 temperaments that temper it out include hemififths and amity, to name two. Edos that temper it out include 12, 29, 34, 41, 46, 53, 58, 87, 94, 99, 111, 140, 145, 152, 239, 292, 391, etc. See Hemifamity family for the rank-3 family where it is tempered out. See Hemifamity temperaments for a collection of rank-2 temperaments where it is tempered out.
Sagittal notation
In the Sagittal system, the downward version of this comma (possibly tempered) is represented by the sagittal and is called the 7/5 kleisma, or 7/5k for short, because the simplest interval it notates is 7/5, as for example in B-F . The upward version is called 5/7k or 7/5k up and is represented by .
Etymology
The name hemifamity was given by Gene Ward Smith in 2005 as a contraction of hemififths and amity[1].
An alternate name for the comma, the aberschisma, was given by Tristan Bay in 2024 in reference to groundfault's aberrismic theory, being the difference between two of the most common aberrismas in just intonation (81/80 and 64/63).