5/3
| Interval information |
classic(al) major sixth,
ptolemaic major sixth
(Shannon, [math]\sqrt{nd}[/math])
[sound info]
In 5-limit just intonation, 5/3 is the just major sixth, classic(al) major sixth, or ptolemaic major sixth[1] of about 884.4¢. It represents the difference between the 5th and 3rd harmonics, and appears in just chords such as 3:4:5 (a 2nd inversion major triad). Its inversion is 6/5, the 5-limit minor third. It differs from the Pythagorean major sixth of 27/16 (about 905.9¢) by the syntonic comma of 81/80 (about 21.5¢). This means that in systems which temper out the syntonic comma, such as 12edo and meantone systems, 5/3 and 27/16 are conflated.
5/3 has a more mellow sound than 27/16, owing to its simpler beating pattern as well as its smaller size.
Approximation
5/3 is very accurately approximated by 19edo (14\19), and hence the enneadecal temperament.