Augmented Sixth Chords

Theory Things William Wieland

2 pitches (the A6) resolve to the dominant by ½ step.
raised 4   5   lowered 6   5		fi   sol   le  sol			Play   8va bassa

All augmented sixth chords also include tonic.
Italian Sixth Chord Play   8va bassa	— only 3 notes (A6 + tonic) — since it does not have 4 notes   it has a hole, like macaroni	c: It6 V	Beethoven Bagatelle no. 1   (on this page)
German Sixth Chord * Play   8va bassa	— 4 notes (A6 + major triad) — reliable, like a dominant 7th   (enharmonically equivalent) — the cadential 6/4 avoids   parallel fifths.	c: Gr6  V 6 – 5 4 – 3	Joplin The Chrysanthemum   (on page 1)
French Sixth Chord Play   8va bassa	— 4 notes (A6 + two M3) — mysterious, like tritones   and the whole tone scale	c: Fr6 V	Joplin The Cascades   (top of p. 4)

Chromaticism — EVERY part on this page either moves by half step or remains on the same tone!

Note — Augmented sixth chords may trick you. We identify chords by stacking pitches in thirds, line-line-line or space-space-space, i.e. every other letter. However, F#-Ab-C-Eb is not a common seventh chord. How can you tell? F sharp up to A flat is a diminished 3rd. (Diminished 3rds are enharmonically equivalent to major 2nds.)

DryErasedTheory - Augmented Sixth Chord Review (3:30) — awesome video by richard johnson

* Doubly Augmented Sixth Chord Play   8va bassa

— another spelling   of the German Sixth   (enharmonically equivalent) — used in major keys

C: Gr6  V 6 – 5 4 – 3

Ask me the “nationality”!