Diaschismic
Diaschismic, sometimes known as srutal in the 5-limit, is a half-octave temperament generated by a perfect fifth or that minus a half-octave period, which is a semitone representing 16/15. Two of these semitones give a whole tone of 9/8, so the diaschisma, 2048/2025, is tempered out. We also have a whole tone plus a period represent 8/5, and in the canonical extension to the 7-limit, the fifth is tuned a little sharp such that eight of them octave reduced (an augmented fifth) minus a period approximate 8/7, tempering out the starling comma, 126/125.
A stack of twelve perfect fifths octave reduced (a diesis) is close in size to a quartertone, and that plus a period can be used to represent 16/11. Three more fifths on top of 16/11 give 16/13. Finally, since the whole tone has been split in two, each can be used to represent 17/16~18/17. Therefore, diaschismic is most naturally viewed as a full 17-limit temperament, tempering out 126/125, 136/135, 176/175, 196/195, and 256/255.
See Diaschismic family #Diaschismic for technical data.
Interval chain
In the following table, odd harmonics and subharmonics 1–21 are in bold.
| # | Period 0 | Period 1 | ||
|---|---|---|---|---|
| Cents* | Approximate ratios | Cents* | Approximate ratios | |
| 0 | 0.0 | 1/1 | 600.0 | 17/12, 24/17 |
| 1 | 703.9 | 3/2 | 103.9 | 16/15, 17/16, 18/17 |
| 2 | 207.7 | 9/8 | 807.7 | 8/5 |
| 3 | 911.6 | 17/10, 22/13 | 311.6 | 6/5 |
| 4 | 415.4 | 14/11 | 1015.4 | 9/5 |
| 5 | 1119.5 | 21/11, 40/21, 48/25 | 519.5 | 27/20 |
| 6 | 623.1 | 10/7 | 23.1 | 56/55, 64/63, 81/80 |
| 7 | 127.0 | 14/13, 15/14 | 727.0 | 32/21 |
| 8 | 830.8 | 21/13, 34/21 | 230.8 | 8/7 |
| 9 | 334.7 | 17/14, 40/33 | 934.7 | 12/7 |
| 10 | 1038.5 | 20/11 | 438.5 | 9/7 |
| 11 | 542.4 | 15/11 | 1142.4 | 27/14, 64/33 |
| 12 | 46.2 | 36/35, 40/39, 45/44, 50/49 | 646.2 | 16/11 |
| 13 | 750.1 | 17/11, 20/13 | 150.1 | 12/11 |
| 14 | 253.9 | 15/13 | 853.9 | 18/11 |
| 15 | 957.8 | 45/26, 68/39 | 357.8 | 16/13 |
| 16 | 461.6 | 17/13 | 1061.6 | 24/13 |
| 17 | 1165.5 | 51/26, 96/49, 108/55 | 565.5 | 18/13 |
* In 17-limit CWE tuning, octave-reduced
As a detempereament of 12et
Diaschismic is naturally considered as a detemperament of the 12 equal temperament. The diagram on the right shows a 58-tone detempered scale, with a generator range of -14 to +14. 58 is the largest number of tones for a mos where intervals in the 12 categories do not overlap. Each category is divided into four or five qualities separated by 6 generator steps, which represent the syntonic comma. Combining this division with the minor and major diatonic qualities of the 12 equal temperament, diaschismic gives us nine or ten qualities for each diatonic category in addition to the five qualities in the tritone region.
The 13th harmonic is just beyond the specified generator range, so the diagram does not show it.
Notice also the little interval between the largest of a category and the smallest of the next. This interval spans 46 generator steps, so it vanishes in 46edo, but is tuned to the same size as the syntonic comma in 58edo. 104edo tunes it to one half the size of the syntonic comma, which may be seen as a good compromise.
Chords
Tunings
Tuning spectrum
| Edo generator |
Eigenmonzo (unchanged-interval)* |
Generator (¢) | Comments |
|---|---|---|---|
| 17/9 | 698.955 | ||
| 7\12 | 700.000 | 12f val, lower bound of 7-, 9- and 11-odd-limit diamond monotone | |
| 3/2 | 701.955 | ||
| 15/14 | 702.778 | ||
| 41\70 | 702.857 | 70ef val | |
| 7/5 | 702.915 | ||
| 21/20 | 703.107 | ||
| 15/11 | 703.359 | ||
| 15/13 | 703.410 | ||
| 34\58 | 703.448 | Lower bound of 13-, 15-, 17-odd-limit, and 17-limit 21-odd-limit diamond monotone | |
| 11/10 | 703.500 | ||
| 9/7 | 703.508 | ||
| 13/10 | 703.522 | ||
| 13/11 | 703.597 | ||
| 12/7 | 703.681 | ||
| 13/9 | 703.728 | ||
| 11/9 | 703.757 | ||
| 21/13 | 703.782 | ||
| 49/48 | 703.783 | ||
| 13/12 | 703.839 | ||
| 61\104 | 703.846 | 104c val | |
| 21/11 | 703.893 | ||
| 11/6 | 703.895 | ||
| 7/4 | 703.897 | ||
| 13/8 | 703.965 | ||
| 17/14 | 704.014 | ||
| 17/13 | 704.027 | ||
| 13/7 | 704.043 | ||
| 11/8 | 704.057 | ||
| 36/35 | 704.064 | ||
| 17/11 | 704.126 | ||
| 21/16 | 704.174 | ||
| 21/17 | 704.272 | ||
| 27\46 | 704.348 | Upper bound of 11-, 13-, 15-, 17-odd-limit, and 17-limit 21-odd-limit diamond monotone | |
| 11/7 | 704.377 | ||
| 9/5 | 704.399 | ||
| 17/16 | 704.955 | ||
| 5/3 | 705.214 | ||
| 25/24 | 705.866 | ||
| 20\34 | 705.882 | 34ef val, upper bound of 7- and 9-odd-limit diamond monotone | |
| 17/10 | 706.214 | ||
| 5/4 | 706.843 | ||
| 17/15 | 708.343 | ||
| 15/8 | 711.731 |
* Besides the octave