183edo

The 183 equal divisions of the octave (183edo), or the 183(-tone) equal temperament (183tet, 183et) when viewed from a regular temperament perspective, divides the octave into 183 equal parts of 6.557 cents each.

Theory

183edo is notable as a higher limit system, especially when 7 is left out of the picture. It tempers out the schisma, 32805/32768, in the 5-limit. In the 7-limit, it tempers out porwell, 6144/6125, cataharry, 19683/19600 and mirkwai, 16875/16807. In the 11-limit, it tempers out 540/539, 3025/3024 and 8019/8000; in the 13-limit, 351/350 and 676/675; in the 17-limit 442/441, 561/560 and 715/714; and in the 19-limit 456/455. It is the optimal patent val for 13-, 17- and 19-limit mirkat temperament, the 72&183 temperament, and an excellent tuning for the rank-3 temperaments madagascar and borneo.

As a no-sevens temperament, it tempers out 32805/32768, 5632/5625, 8019/8000, 676/675, 4425/4424, 6656/6655, 936/935, 1089/1088, and 1377/1375.

Prime harmonics

183edo is notable as having especially low error in all prime limits from 11 to 29 for EDOs in the 100 to 200 range, compared using a variety of metrics (prime error punishments), although it has a bad 19 which causes it to fail to be consistent in the 19-odd-limit. It is however a strong no-19's system, being consistent in the no-19's no-35's 29-prime-limited 45-odd-limit add-43. (The prime 43 is added in the set of odd harmonics due to its essentially perfect accuracy. The harmonic 35 is excluded due to the sharpness of 7 compounding and causing inconsistency in some cases such as for 39/35.) It can also be considered to model the 2.17.29.43 subgroup with extreme accuracy.