German sixth chord: Difference between revisions

Per discussion, the 7-limit interpretation shouldn't be presented as historical. Copypaste some information from the 7/4 page
Bcmills (talk | contribs)
Give the reason for the choice of 128:160:192:225 over 72:90:108:125 in the 5-limit; clarify that the meantone interpretation can include that chord as well; remove discussion of “rare and special dissonance” in the meantone section, since the 4:5:6:7 interpretation is actually consonant.
Line 1: Line 1:
{{Wikipedia|Augmented sixth chord #German sixth}}
{{Wikipedia|Augmented sixth chord #German sixth}}


A '''German sixth chord''' is a [[tetrad]] comprising a root, major third, fifth, and augmented sixth.  
A '''German sixth chord''' is a [[tetrad]] comprising a root, major third, perfect fifth, and augmented sixth, often built on the sixth degree of the minor scale.


In [[meantone]] (including [[12edo]]), on which traditional tonal harmony is built, the augmented sixth is treated as a rare and special dissonance. It is approximately the size of a [[7/4|harmonic seventh (7/4)]], so the chord approximates the [[harmonic seventh chord]]:
== In just intonation ==
* 1 – 5/4 – 3/2 – 7/4 with steps 5/4, 6/5, 7/6.


In 5-limit just intonation, this augmented sixth is likely to be [[225/128]] the Neapolitan augmented sixth, so if we stick to the 5-limit, one possible tuning is given as [[128:160:192:225]].
Because the German sixth chord is often built on the sixth degree of a minor scale, the [[128:160:192:225]] found on the ♭VI of the [[duodene]] is a good candidate for its interpretation in the [[5-limit]].
 
== In meantone ==
 
In [[meantone]], the augmented sixth represents both [[125/72]] and [[225/128]]. In the historically-prevalent [[quarter-comma meantone]] it is tuned only a few cents shy of a just [[7/4]], and in the closely related [[septimal meantone]] it explicitly represents [[7/4]] as well, so the meantone German sixth chord can be considered to approximate both [[4:5:6:7]] and [[128:160:192:225]].