11/10
11/10, the large undecimal neutral second or undecimal submajor second, is an interval favored by Ptolemy. Despite its being tempered together with 12/11 in systems like 24edo, this interval is considerably less exotic than 12/11 in terms of sound- in fact, one could make the argument that it functions a bit more like a narrowed 10/9 owing to its usage in such a capacity in systems like 22edo and 41edo where 11/10 and 10/9 are tempered together.
| Interval information |
undecimal submajor second
reduced
[sound info]
Approximation
11/10 is approximated extremely precisely by 80edo and its multiples, with a chain of 80 11/10's failing to close at the octave by a mere third of a cent, close enough that you could theoretically tune an instrument to 80edo by ear using it if you had the patience.
Temperaments
11/10 is treated as a comma in edos 1, 2, 3, 5, and some very low accuracy temperaments such as antietam. If it is used as a generator instead, it produces porcupine, although it is slightly sharper than the optimal tuning for porcupine and does not fit the 80edo patent val mapping.
Trivia
Coincidentally, the interval between the most common tuning frequency (A440) and the second most common AC electrical frequency (50 Hz) is exactly 44/5, or three octaves above an 11/10.