In music, septimal diesis (or slendro diesis) is an interval with the ratio of 49:48 , which is the difference between the septimal whole tone and the septimal minor third. It is about 35.7 cents wide, which is narrower than a

quarter-tone A quarter tone is a pitch halfway between the usual notes of a chromatic scale or an interval about half as wide (aurally, or logarithmically) as a semitone, which itself is half a whole tone. Quarter tones divide the octave by 50 cents each, a ...

but wider than the septimal comma. It may also be the ratio 36:35, or 48.77 cents.

In equal temperament

12 equal temperament Twelve-tone equal temperament (12-TET) is the musical system that divides the octave into 12 parts, all of which are equally tempered (equally spaced) on a logarithmic scale, with a ratio equal to the 12th root of 2 ( ≈ 1.05946). That result ...

this interval is not tempered out; the septimal whole tone and septimal minor third are replaced by the normal whole tone and minor third. This makes the diesis a semitone, about twice its "correct" size. The septimal diesis is tempered out by a number of equally tempered tuning systems, including 19-ET, 24-ET and 29-ET; these tunings do not distinguish between the septimal whole tone and septimal minor third. It is not tempered out however by 22-ET or 31-ET (or indeed any equal temperament with at least 30 steps).

References

{{Intervals, state=expanded Commas (music) 0049:0048 7-limit tuning and intervals

In equal temperament

See also

References