A♭ diminished major 7th chord on bass (A♭dimMaj7)

Why it sounds like that

A♭ diminished major 7th is built from the formula 1, ♭3, ♭5, 7. The diminished 5th between A♭ and E♭♭ creates a tritone that gives the chord its dark color. The major 7th G is a leading tone that resolves upward to A♭. Compare with A♭ minor 7th flat 5th, which has G♭ instead of G.

What goes wrong with A♭ diminished major 7th?

• Letting the ring finger mute the 2nd string, which silences the C♭.
• Pressing the pinky too lightly, causing the 2nd string to buzz.
• Allowing the index finger to drift sharp, making the 4th string note out of tune.

When to use it

A♭ diminished major 7th works as a passing chord in A♭ minor, often between A♭ minor and A♭ minor 7th. Its tense sound suits jazz ballads and dramatic film cues. Use it to add chromatic motion on the bass.

Changing to and from A♭ diminished major 7th

• Sliding the shape down two frets to the 2nd fret gives F♯ diminished major 7th.
• Sliding the shape up one fret to the 5th fret gives A diminished major 7th.

Which voicing to use

The 4th-fret position places the root A♭ on the 4th string, giving a solid low foundation. The A♭dimM7/F♯♯ inversion at the 1st fret puts G in the bass, creating a different color while keeping the same notes.