Diminished Chords

Diminished triads are chords built from stacked minor-thirds. A diminished triad has three notes: the root of the chord, a note a minor-third above the root, and a note a diminished-fifth above the root. The diminished chord gets its name from this diminished-fifth interval.

 

If we stack another minor-third on top of a diminished triad, we get a diminished-seventh chord. This creates and interval of a diminished-seventh above the root of the chord. This interval is what gives the diminished-seventh chord its name.

Diminished-seventh Chord

 If we instead add a major-third on top of a diminished triad we get a half-diminished-seventh chord.

Half-diminished-seventh Chord

 

Diminished chords are usually indicated with the following symbols: “°” or “dim” for diminished triads, “°7” or “dim7” for diminished-seventh chords, “ø7” or “m7♭5”

Chord symbols for diminished chords

Diminished chords have an unstable sound and usually resolve to a major or minor chord one half-step higher.

Normal resolution of diminished chords

Diminished chords can also resolve in less common ways, such as the following:

Other resolutions of diminished chords

Augmented Sixth Chords

If we have a minor chord in first inversion the interval between the bass note and the root of the chord is a Major sixth.

If we then raise the tonic note (by an augmented unison), the interval between the bass note and root note becomes an augmented sixth. A chord with this interval of an augmented sixth is called an Augmented Sixth Chord.

The three basic types of Augmented sixth chords:

An Italian Sixth Chord has an augmented sixth between the bass and root of the chord, with the fifth of the chord in-between the bass note and root.

A German Sixth is like the Italian sixth but with one extra note placed a perfect fifth above the bass note.

A French Sixth is like the Italian sixth but with one extra note placed a Augmented fourth above the bass note.

The resolutions of Augmented sixth chords:

Italian and French Sixth chords will most often resolve to a dominant chord.

The German Sixth will most often resolve to a dominant or tonic chord. (It is worth noting that if the German Sixth resolves to the dominant then parallel fifths will occur, which can cause musical lines to lose their independence in certain styles of music.)