20:25:30:36

Chord information

Harmonics	20:25:30:36
Subharmonics	1/(45:36:30:25)
Intervals from root	1/1 – 5/4 – 3/2 – 9/5
Cents from root	0¢ 386¢ 702¢ 1018¢
Step intervals	5/4, 6/5, 6/5
Step cents	386¢, 316¢, 316¢
Prime limit	5
Genus	32 ⋅ 52 (225)
Intervallic odd limit	25
Otonal odd limit	25
Utonal odd limit	45
Consistent edos (d ≥ 2)	19edo**, 34edo*, 38edo*, 46edo*, …
* 2 ≤ d < 4; ** 4 ≤ d < 8; *** 8 ≤ d < 16; …

The major-minor seventh chord is a tetrad in 5-limit harmony, tuned 20:25:30:36 (1⁄1–5⁄4–3⁄2–9⁄5) and sometimes considered a form of dominant seventh chord. It combines a 5/4 major third with the consonant 9/5 seventh that would be found in a Ptolemaic minor seventh chord on the same root, creating a 36/25 tritone between the two.

The major-minor seventh chord is found rooted at 1⁄1 (I) and 4⁄3 (IV) in the duodene.

In septimal meantone, the 36/25 tritone is equated with the more consonant interval 10/7, and the major-minor seventh chord becomes an essentially tempered chord in the 9-odd-limit.