Double stops

Everything so far has been one note at a time. Play two together, on strings next to each other, and the guitar stops sounding like a single voice and starts sounding like a section. It is the oldest trick in blues rhythm playing and it costs you nothing you do not already have: both notes are in the box.

The neck at the top rings every pair the position holds on the top three strings. Below it each pair has a row, and each cell has two marks — the higher string above the lower one — because a pair does not have one job over a chord. It has two, one for each note, and that is the whole interest of it.

Reading a pair

Take the ♭3 and the 5 together, at the fifth fret of the third and second strings. Over A7 the upper note is the chord’s fifth and sits still while the lower one is the blue third and wants to bend. Over D7 they swap: the ♭3 becomes the chord’s seventh and rests, and the 5 is the note that has to move. Neither of them is wrong in either bar. They simply take turns being the anchor.

That is why a pair sounds fuller than either note alone. Whichever chord is sounding, one of the two is usually at home, so the pair always has something to hold on to while the other note does the talking.

Playing them

Fret both notes with one finger where the frets are level, or with two where they are not, and strike both strings together. Let them ring. A pair held through a change and then moved a fret is most of a rhythm part, and a pair played twice — once plain, once with the lower note bent — is most of a phrase.