Tetrahanson
The tetrahanson temperament is a nonoctave kleismic temperament, tempering out the kleisma in the 4.3.5 subgroup and repeating at the double octave 4/1. It is generated by 5/3 and, like in normal hanson temperament, 6 of them make a 4/3. Tetrahanson does not contain any 5-limit major or minor triads, but it does have different voicings of them (3:4:5 and 12:15:20), which, to a 12edo-accustomed listener, can make it sound like the root is the real root and the perfect fifth above it at the same time.
For technical information see Subgroup temperaments#Tetrahanson.
Interval chain
| Generators | Cents (CTE) | Approximate ratios |
|---|---|---|
| -7 | 1019.413 | 9/5 |
| -6 | 1902.354 | 3/1 |
| -5 | 385.295 | 5/4 |
| -4 | 1268.236 | 25/12 |
| -3 | 2151.177 | 125/36 |
| -2 | 634.118 | 36/25 |
| -1 | 1517.059 | 12/5 |
| 0 | 0.000 | 1/1 |
| 1 | 882.941 | 5/3 |
| 2 | 1765.882 | 25/9 |
| 3 | 248.823 | 144/125 |
| 4 | 1131.764 | 48/25 |
| 5 | 2014.705 | 16/5 |
| 6 | 497.646 | 4/3 |
| 7 | 1380.587 | 20/9 |
Tetrahanson on tritave
In tritave-repeating tetrahanson (3.4.5 subgroup), 36/25 actually represents 1\3edt, which makes the 3rd-tritave period.
b39 & b15
This is restriction of catalan extension. This can maintain the structure of the 3rd-octave period in 3.4.5, 3.5.11, and 3.5.13. The tuning results are clearly affected by whether or not the basis includes 11.
| 3.4.5 | 3.5.11 | 3.5.13 | |
|---|---|---|---|
| CWE | 883.071 | 879.416 | 883.808 |
| Badness (Dirichlet) | 0.155 | 2.708 | 0.069 |
| 3.4.5.11 | 3.4.5.13 | 3.5.11.13 | |
| CWE | 880.672 | 882.854 | 879.352 |
| Badness (Dirichlet) | 0.384 | 0.066 | 0.44 |
| # (mingen) |
Period 0 | Period 1 | Period 2 | |||
|---|---|---|---|---|---|---|
| Cents* | Approximate Ratios | Cents* | Approximate Ratios | Cents* | Approximate Ratios | |
| -1 | 1652.9 | 13/5 | 384.9 | 5/4 | 1018.9 | 9/5 |
| 0 | 0.0 | 1/1 | 634.0 | 36/25, 13/9 | 1268.0 | 25/12, 27/13 |
| 1 | 249.1 | 125/108, 15/13 | 883.1 | 5/3 | 1517.1 | 12/5 |
| 2 | 498.2 | 4/3, 33/25 | 1132.2 | 48/25, 25/13 | 1766.1 | 25/9, 36/13, 11/4 |
| 3 | 747.3 | 20/13, 55/36 | 1381.2 | 20/9, 11/5 | 113.3 | 16/15, 55/52 |
| 4 | 996.3 | 16/9, 44/25 | 1630.3 | 64/25,33/13 | 362.4 | 100/81, 16/13, 11/9 |
* In 3.4.5-subgroup CWE tuning