347edo
| ← 346edo | 347edo | 348edo → |
347 equal divisions of the octave (abbreviated 347edo or 347ed2), also called 347-tone equal temperament (347tet) or 347 equal temperament (347et) when viewed under a regular temperament perspective, is the tuning system that divides the octave into 347 equal parts of about 3.46 ¢ each. Each step represents a frequency ratio of 21/347, or the 347th root of 2.
Theory
The equal temperament tempers out [32 -7 -9⟩ (escapade comma) and [54 -37 2⟩ (monzisma), 3136/3125, 420175/419904, and 5250987/5242880 in the 7-limit. It provides an excellent tuning for sengagen, the 99 & 248 temperament tempering out both 3136/3125 and 420175/419904, and the rank-3 hemimean temperament tempering out 3136/3125.
Extending it to the 11-limit requires choosing which mapping one wants to use, as both are nearly equally far off the mark. It makes more sense as a 2.3.5.7.13 subgroup temperament, where it tempers out 676/675 and 4096/4095, or as a 2.3.5.7.13.19 subgroup temperament, where it tempers out 1521/1520 and 1729/1728.
Prime harmonics
| Harmonic | 2 | 3 | 5 | 7 | 11 | 13 | 17 | 19 | 23 | 29 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Error | absolute (¢) | +0.00 | +0.06 | +1.01 | -0.53 | -1.46 | -0.18 | -1.21 | -0.11 | +1.12 | +0.97 | -0.37 |
| relative (%) | +0 | +2 | +29 | -15 | -42 | -5 | -35 | -3 | +32 | +28 | -11 | |
| Steps (reduced) |
347 (0) |
550 (203) |
806 (112) |
974 (280) |
1200 (159) |
1284 (243) |
1418 (30) |
1474 (86) |
1570 (182) |
1686 (298) |
1719 (331) | |
Subsets and supersets
347edo is the 69th prime edo.
Regular temperament properties
| Subgroup | Comma List | Mapping | Optimal 8ve Stretch (¢) |
Tuning Error | |
|---|---|---|---|---|---|
| Absolute (¢) | Relative (%) | ||||
| 2.3 | [550 -347⟩ | [⟨347 550]] | -0.0197 | 0.0197 | 0.57 |
| 2.3.5 | [32 -7 -9⟩, [-22 30 -11⟩ | [⟨347 550 806]] | -0.1576 | 0.1956 | 5.66 |
| 2.3.5.7 | 3136/3125, 420175/419904, 5250987/5242880 | [⟨347 550 806 974]] | -0.0713 | 0.2259 | 6.53 |
Rank-2 temperaments
| Periods per 8ve |
Generator* | Cents* | Associated Ratio* |
Temperaments |
|---|---|---|---|---|
| 1 | 7\347 | 24.21 | 686/675 | Sengagen |
| 1 | 16\347 | 55.33 | 16875/16384 | Escapade |
| 1 | 69\347 | 238.62 | 147/128 | Tokko |
| 1 | 72\347 | 248.99 | [-26 18 -1⟩ | Monzismic |
| 1 | 146\347 | 504.90 | 104976/78125 | Countermeantone |
* octave-reduced form, reduced to the first half-octave, and minimal form in parentheses if it is distinct