F diminished major 7th chord on bass (FdimMaj7)

Why it sounds like that

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

What goes wrong with F diminished major 7th?

• Letting the ring finger flatten onto the 2nd string, which deadens the A♭.
• Pressing the index finger too hard, causing the 4th string to buzz against the fret.
• Allowing the pinky to drift sharp, making the 2nd string note sound out of tune.

When to use it

F diminished major 7th works as a passing chord in F minor, often between F minor and F 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 F diminished major 7th

• Sliding the shape up one fret to the 2nd fret gives F♯ diminished major 7th.
• Sliding the shape up two frets to the 3rd fret gives G diminished major 7th.

Which voicing to use

The 1st-fret position places the root F on the 4th string, giving a solid low foundation. The FdimM7/E inversion at the 1st fret puts E in the bass, creating a different color while keeping the same notes.