On The Augmented Sixth

 Probably my second favourite secondary dominant and it’s an old one. There are four variations, three of which (Italian, German and French) are functional as secondary dominant chords (the fourth is known as the Swiss and is used more rarely). To describe the chord in its simplest form, it is an incomplete V7 of V with a lowered fifth. The Italian structure of the chord is, in four part harmony, lowered sixth; tonic (tenor); tonic (alto); raised fourth. It should now be obvious why it is called an augmented sixth now, because of the interval between the lowest and highest pitched notes. Yeah nice.

 Using it’s traditional functionality as a secondary dominant in C, we have the notes AbCCF# in the Italian chord. These resolve as follows: Ab down to G, lower C down to B, upper C rises to D and the F# resolves to G. Wow! We have now reached the dominant chord. The vibraphone setting on the Casiotone CT-370 works very well.

 Furthermore, we are not limited to this function. Take the French chord for example. Why not use it purely as a substitution (or rather re-enactment) of the dominant of the chosen key? Well the jazz world gave it a go. Radical.

 And it’s not just Jazz, Baroque and obscure romantic concertos we can explore the use of the A6. On you Yamaha YPT200-K, play an augmented sixth chord as I have described, but construct it on an arbitrary scale degree. A particularly obscure, not to mention quintessential, chord is that created by these means on the lowered second degree in a dominant seventh chord, but I need to leave some things to write about at later dates or I will clock too many hours on NBA Jam.

 So in summary, there are various ways to treat this chord and all add a colour and function to what may otherwise be dull superposition of sonic vibrations.