Dubhe
Dubhe is a temperament in the 3.5.7.17 subgroup generated by a sharp ~17/15 (or equivalently a flat ~45/17). As a weak extension of BPS, it tempers out the sensamagic comma, 245/243, while splitting the BPS generator of ~9/7 in two (by tempering out 2025/2023) so that a stack of two generators represents 9/7, and a stack of four generators represents 5/3 in addition to 81/49, which generates MOS scales of 8L 1s and 9L 8s against the tritave. The "canonical" tuning for the generator is 3\26edt, representing the double Bohlen-Pierce scale, but a range of other tunings are valid, including 2\17edt and 5\43edt.
For technical data, see No-twos subgroup temperaments#Dubhe.
Interval chain
In the below, tritave-reduced harmonics 1–17 are indicated in bold. All ratios are considered to be in the 287-throdd limit.
| # | Cents* | Approximate Ratios |
|---|---|---|
| 0 | 0.0 | 1/1 |
| 1 | 220.3 | 17/15, 135/119, 175/153 |
| 2 | 440.6 | 9/7, 35/27 |
| 3 | 660.9 | 25/17, 51/35, 119/81 |
| 4 | 881.1 | 5/3, 81/49 |
| 5 | 1101.4 | 17/9, 225/119, 459/245 |
| 6 | 1321.7 | 15/7, 175/81 |
| 7 | 1542.0 | 17/7, 125/51 |
| 8 | 1762.2 | 25/9, 135/49 |
| 9 | 80.5 | 51/49, 85/81, 125/119 |
| 10 | 300.8 | 25/21 |
| 11 | 521.1 | 85/63 |
| 12 | 741.4 | 75/49, 125/81 |
| 13 | 961.7 | 85/49 |
| 14 | 1181.9 | 125/63 |
Tuning spectrum
| Edt Generator |
Eigenmonzo (Unchanged-interval) |
Generator (¢) |
Comments |
|---|---|---|---|
| 17/15 | 216.687 | Untempered tuning | |
| 4\35 | 217.366 | ||
| 7/3 | 217.542 | 1/2-fidesma | |
| 7\61 | 218.257 | ||
| 10\87 | 218.616 | ||
| 49/45 | 219.316 | ||
| 17/7 | 219.447 | ||
| 3\26 | 219.456 | Double Bohlen-Pierce | |
| 7/5 | 219.907 | ||
| 220.170 | DR 3:5:7 | ||
| 17/9 | 220.209 | ||
| 11\95 | 220.226 | ||
| 25/21 | 220.380 | ||
| 8\69 | 220.518 | ||
| 5/3 | 221.090 | ||
| 5\43 | 221.158 | ||
| 7\60 | 221.895 | ||
| 175/81 | 222.272 | ||
| 9\77 | 222.306 | ||
| 25/17 | 222.557 | ||
| 2\17 | 223.759 | ||
| 35/27 | 224.637 |