# Septimal diesis

In music, **septimal diesis** (or **slendro diesis**) is an interval with the ratio of 49:48^{[citation needed]} play (help·info), 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 but wider than the septimal comma. It may also be the ratio 36:35,^{[1]}^{[2]}^{[3]} or 48.77 cents. Play (help·info)

## In equal temperament[edit]

In 12 equal temperament 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).

## See also[edit]

## References[edit]

**^**Haluska, Jan (2003).*The Mathematical Theory of Tone Systems*, p.xxv. ISBN 978-80-88683-28-5.**^**"Stichting Huygens-Fokker: List of intervals". Huygens-fokker.org. Retrieved 2013-10-18.**^**"Wendy Carlos Beta scale". Microtonal-synthesis.com. Retrieved 2013-10-18.