Augmented 6th Chords

Augmented 6^th Chords

There are three chromatic chords which contain the interval of an augmented 6^th; the Italian 6^th, French 6^th and German 6^th, collectively known as the “augmented 6^th chords”.

Augmented 6^th chords have as their root note the raised 4^th above the tonic, e.g. F# in the key of C major or C minor. This note is the leading note to the dominant (F#àG), and the chord behaves like a secondary dominant (Aug6àV).

The chords are usually (but not exclusively) written in first inversion.

To build an augmented 6^th chord:

• take the tonic note of the prevailing key,
• add the note a major third lower, (you will need an accidental in major keys) and
• the note an augmented 4^th higher (accidental always needed).

These three notes create the “Italian 6^th” chord.

The distance between the bass note (Ab) and the root (F#) is an augmented 6^th.

Adding a 4^th note which is a major 2^nd higher than the tonic note creates a “French 6^th”.

Adding a 4^th note which is a minor 3^rd higher than the tonic creates a “German 6^th”.

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The German 6^th is an enharmonic equivalent of the dominant 7^th chord – the same notes but spelled differently. For example, the German 6^th in A minor (see above) is a re-spelling of the dominant 7^th chord in Bb major:

Tip: To remember the names of the augmented chords, think of the geography of the countries. Italy is furthest south, and has 3 notes. France is more northern (up) and has a higher additional note. Germany is more northern still, and has the highest additional note.

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Examples of all three augmented 6^th chords can be found frequently in Classical music and onwards (1750+), but these chords are less used in older (Baroque) styles.

Italian 6^th in Mozart’s Fantasy in C minor (K475):

French 6ths in Mozart’s Sonata in Am (K310):

Notice how the bass moves up/down by a semitone.

German 6^th in the same sonata:

Notice how the bass moves down chromatically through G-F#-F-E.