F Minor 6th
m6
0 - 3 - 7 - 9Minor + major 6th
About F Minor 6th
F minor sixth is a first-fret barre with a note added — F, A♭, C, D — and it is one of the harder chords in common use. Its main role is not as a minor chord at all: over a B♭ bass it becomes B♭9, and that substitution is why it appears in charts where no F minor is written.
The notes
F, A♭, C, D. The D is the major sixth, sitting a whole tone above the C. Against the A♭ it produces the characteristic brightness-over-darkness of the minor sixth.
Read from D the same notes give D half-diminished. Between that reading, the B♭9 reading and the plain F minor sixth, the chord has three functions and one shape.
On the fretboard
First fret with the root on the low E string, or eighth with the root on the A. The eighth-fret position is the practical one for the same reason it always is in F.
The three-string version on the middle strings is what gypsy jazz uses, where the rhythm matters more than the fullness and the bass is covered by another instrument.
Where it shows up
As a rootless B♭9 in jazz comping — its most common modern use — and as a tonic in F minor swing.
It also appears in minor blues in F, a horn key, which means a guitarist meets this chord in ensemble playing rather than in anything written on the instrument.
The chord also explains why jazz guitarists learn minor sixths before minor sevenths in some traditions: as rootless dominants they cover more ground, and the shape is the same one the rhythm style needs anyway.