612edo
| ← 611edo | 612edo | 613edo → |
The 612 equal divisions of the octave (612edo), or the 612(-tone) equal temperament (612tet, 612et) when viewed from a regular temperament perspective, is the equal division of the octave into 612 parts of about 1.96 cents each, a size close to 32805/32768, the schisma.
Theory
612edo is a very strong 5-limit system, a fact noted by Bosanquet and Barbour. It tempers out the sasktel comma, [485 -306⟩, in the 3-limit, and in the 5-limit [-52 -17 34⟩, the septendecima, [1 -27 18⟩, the ennealimma, [-53 10 16⟩, the kwazy comma, [54 -37 2⟩, the monzisma, [-107 47 14⟩, the fortune comma, and [161 -84 -12⟩, the atom. In the 7-limit it tempers out 2401/2400 and 4375/4374, so that it supports the ennealimmal temperament, and in fact provides the optimal patent val for ennealimmal. The 7-limit val for 612 can be characterized as the ennealimmal commas plus the kwazy comma. In the 11-limit, it tempers out 3025/3024 and 9801/9800, so that 612 supports the hemiennealimmal temperament. In the 13-limit, it tempers 2200/2197 and 4096/4095.
The 612edo has been proposed as the logarithmic interval size measure skisma (or sk), since one step is nearly the same size as the schisma (32805/32768), 1/12 of a Pythagorean comma or 1/11 of a syntonic comma. Since 612 is divisible by 2, 3, 4, 6, 9, 12, 17, 18, 34, 36, 51, 68, 102, 153, 204 and 306, it can readily express the step sizes of the 12, 17, 34, 68 and 72 divisions. A table of intervals approximated by 612 can be found under Table of 612edo intervals.
Prime harmonics
| Harmonic | 2 | 3 | 5 | 7 | 11 | 13 | 17 | 19 | 23 | 29 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Error | Absolute (¢) | +0.000 | +0.006 | -0.039 | -0.198 | -0.338 | +0.649 | +0.927 | +0.526 | -0.823 | -0.165 | +0.062 |
| Relative (%) | +0.0 | +0.3 | -2.0 | -10.1 | -17.2 | +33.1 | +47.3 | +26.8 | -42.0 | -8.4 | +3.2 | |
| Steps (reduced) |
612 (0) |
970 (358) |
1421 (197) |
1718 (494) |
2117 (281) |
2265 (429) |
2502 (54) |
2600 (152) |
2768 (320) |
2973 (525) |
3032 (584) | |
Regular temperament properties
| Subgroup | Comma list | Mapping | Optimal 8ve stretch (¢) |
Tuning error | |
|---|---|---|---|---|---|
| Absolute (¢) | Relative (%) | ||||
| 2.3.5 | [1 -27 18⟩, [-53 10 16⟩ | [⟨612 970 1421]] | |||
| 2.3.5.7 | 2401/2400, 4375/4374, [-53 10 16⟩ | [⟨612 970 1421 1718]] | |||
| 2.3.5.7.11 | 2401/2400, 3025/3024, 4375/4374, 2791309312/2790703125 | [⟨612 970 1421 1718 2117]] | |||
| 2.3.5.7.11.13 | 2200/2197, 2401/2400, 3025/3024, 4096/4095, 24192/24167 | [⟨612 970 1421 1718 2117 2265]] | |||
| 2.3.5.7.11.13.19 | 676/675, 1001/1000, 1216/1215, 1331/1330, 1540/1539, 1729/1728 | [⟨612 970 1421 1718 2117 2265 2600]] | |||