A diminished7

Today's guitar chord of the day is A diminished7.This is quite a common inversion of a diminished chord. You sometimes see diminished chords written as A diminished, A dim, A° or A°7. Officially the diminished chord has only 3 notes whilst the diminished 7th has four, however you're usually pretty safe playing a diminished 7th chord in all circumstances if you want to.

Diminished 7th chords have an interesting and really useful property: they're made up of four equal minor 3rd intervals (3 semitones). This means that every note in the chord is a potential root note. you can move this chord up 3 frets on the guitar and it will still be A diminished 7th. You can keep moving this chord up 3 frets a time and it will stay A diminished 7th.

A diminished 7th has these notes: A, C, Eb, Gb.

You can also take any of the chord notes to be the root note. So we can also call this chord:

A diminished 7th
C diminished 7th
Eb diminished 7th
Gb diminished 7th

Diminished 7th chords are chord vii in minor keys but are usually played as passing chords between one chord and another, for example:
Cmajor7 / C# diminished 7th / Dm7 / G7 /  Cmajor7

A diminished 7th can also be thought of as Ab7b9.

 Tune in tomorrow for another guitar chord of the day!