# 1911edo

← 1910edo | 1911edo | 1912edo → |

^{2}× 13**1911 equal divisions of the octave** (abbreviated **1911edo** or **1911ed2**), also called **1911-tone equal temperament** (**1911tet**) or **1911 equal temperament** (**1911et**) when viewed under a regular temperament perspective, is the tuning system that divides the octave into 1911 equal parts of about 0.628 ¢ each. Each step represents a frequency ratio of 2^{1/1911}, or the 1911th root of 2.

## Theory

1911edo is consistent in the 11-odd-limit. The equal temperament tempers out the aluminium comma in the 5-limit, and it provides the optimal patent val for the protactinium temperament in the 17-limit. However as may stem from consistency only in the 11-limit, the 13th harmonic has a large relative error. As such, 1911edo is best considered as a 2.3.5.7.11.17.19 subgroup tuning.

### Odd harmonics

Harmonic | 2 | 3 | 5 | 7 | 11 | 13 | 17 | 19 | 23 | 29 | 31 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|

Error | Absolute (¢) | +0.000 | +0.086 | -0.128 | +0.091 | +0.016 | +0.289 | -0.089 | +0.132 | +0.297 | +0.250 | -0.295 |

Relative (%) | +0.0 | +13.7 | -20.5 | +14.5 | +2.6 | +46.0 | -14.1 | +21.1 | +47.3 | +39.8 | -46.9 | |

Steps (reduced) |
1911 (0) |
3029 (1118) |
4437 (615) |
5365 (1543) |
6611 (878) |
7072 (1339) |
7811 (167) |
8118 (474) |
8645 (1001) |
9284 (1640) |
9467 (1823) |

### Subsets and supersets

Since 1911 factors into 3 × 7^{2} × 13, 1911edo has subset edos 3, 7, 13, 21, 39, 49, 91, 147, 273, 637.

## Regular temperament properties

### Rank-2 temperaments

Periods per 8ve |
Generator* | Cents* | Associated Ratio* |
Temperaments |
---|---|---|---|---|

13 | 793\1911 (58\1911) |
497.959 (36.421) |
4/3 (?) |
Aluminium |

91 | 793\1911 (16\1911) |
497.959 (10.047) |
4/3 (176/175) |
Protactinium |

* octave-reduced form, reduced to the first half-octave, and minimal form in parentheses if it is distinct