F♯ minor 7th flat 5th chord on bass (F♯m7♭5)

Why it sounds like that

F♯ minor 7th flat 5th is built from the formula 1, ♭3, ♭5, ♭7. The diminished 5th between F♯ and C gives the chord its tense, unresolved quality. Raising the ♭5 to a perfect 5th produces F♯ minor 7th, the closest stable contrast.

What goes wrong with F♯ minor 7th flat 5th?

• Letting the pinky collapse and mute the 2nd string.
• Fretting the 1st string with the ring finger too far from the fret, causing a buzz.
• Allowing the index finger to touch the 3rd string and deaden the F♯.

When to use it

F♯ minor 7th flat 5th functions as the ii chord in E natural minor and the vii chord in G major. Use it in minor-key jazz and blues lines where the half-diminished colour leads to a dominant. It pairs naturally with F♯ minor and F♯ 5th.

Changing to and from F♯ minor 7th flat 5th

• Sliding the shape down one fret to the 1st fret gives F minor 7th flat 5th.
• Sliding the shape up one fret to the 3rd fret gives G minor 7th flat 5th.

Which voicing to use

The 2nd-fret root position keeps F♯ in the bass for a grounded sound. The F♯m7♭5/C inversion at the 8th fret places the diminished 5th in the bass, creating a darker, less stable feel. Choose the F♯m7♭5/E inversion when the bass line needs to descend to E.