Diminished seventh chord

The diminished seventh chord (dim7) – construction, intervals, symbols and examples.

The diminished seventh chord – dim7 – is a diminished triad with a minor third interval added on top of the diminished fifth.

Diminished seventh chord chart

Examples of diminished seventh chords.

Chord chart with some examples of diminished seventh chords for the guitar. Diminished 7th chord diagrams.

Diminished seventh chord intervals

The intervals a diminished seventh chord are built of.

Intervals of the diminished seventh chord: perfect unison, minor third, diminished fifth, sixth.

Chord formula: 1, b3, b5, bb7 (bb7 = 6).

Diminished seventh chord symbols

The chord symbols of the diminished seventh chord.

Symbols: dim7, º7.

Examples: Cdim7, Gdim7, Fº7.

Diminished seventh chord construction

Construction of the diminished seventh chord.

A diminished seventh chord is constructed by adding a minor third on top of the diminished fifth of the diminished triad.

The new interval – diminished fifth (5) + minor third (3) – is equal to the interval diminished minor seventh (bb7), a.k.a double flattend 7th.

The interval diminished minor seventh (bb7) i equal to the interval sixth (6) (see explanation below).

The diminished seventh chord in thirds: minor third (b3) + minor third (b3) + minor third (3).

Cdim -> Cdim7
Add a double flattened 7th (bb7 = 6) to the C diminished triad and Cdim becomes Cdim7.

The double flattened seventh interval – bb7

Explanation of the diminished minor seventh interval a.k.a double flattened 7th interval (bb7) a.k.a the interval sixth.

If the inteval we add is a sixth, how come the chord is a seventh?

What we do is to diminish the dominant seventh interval a semitone from b7 to bb7 and bb7 is equal to a sixth.

So bb7 is the reason to why we have a seventh in the chord name, and bb7 = 6 is the reason to why the interval is actually a sixth.