Minor Soul

A lot of soul sits in a minor key, and the chord that defines it is the minor seventh rather than the plain minor triad. A bare minor chord can sound stark; adding the seventh softens it and makes it sound like it belongs in a groove rather than a lament.

These three are worth having under your fingers, because between them they cover an enormous number of minor soul vamps.

Am7

A minor seventh, open position. Compare it with a plain A minor — one finger comes off the third string, and the whole character changes.

Dm7

D minor seventh.

Em7

E minor seventh, and the easiest chord on the instrument — one finger down, strum all six strings.

A great deal of minor soul is built on just two of these, alternating for the whole song. The commonest pairing is the i chord and the iv — A minor to D minor, for instance — held for a bar or two each and repeated.

When a progression stays that still, everything interesting has to come from what you do inside it. That means rhythm, register and small additions rather than new chords. Play the vamp with triads on the top strings for one pass, then with the open seventh chords for the next, and you have an arrangement.

A voicing worth knowing here is the minor seventh barre, because it lets you take the same two-chord vamp anywhere on the neck.

Am7

A minor seventh as a barre at the fifth fret. Moveable — slide it to the seventh fret and it is B minor seventh.

A smooth soul groove in A minor at 82 beats per minute. Work the vamp with open chords first, then up at the fifth fret, and hear how much the register changes the feel.