There was once a time when any good swing guitarist would read a straight Major chord penned on a chart and automatically turn it into at least a M6 chord. "That" sound of the relative minor for the corresponding Major chord is just plain nice tension.

Along came the Bebop era and the Major chord was automatically played as M6 or Maj7 more times than not.

If the chord had a dom7 written, well turn it into at least a 9th, always listening for places to go even further with that, making it an 11th or more often, a 13 chord. The 13 is way cool as it combines the tension of the dom7 with the tension of the 13, the 13 being nothing but the 6 an octave up. Guitar players often grabbed chords where the 13 really WAS the 6th, being "inside" the octave, but once that 7th is in there somewhere, the tension of the 13 chord rules. "A Tritone and a six" -- LH jazz piano, forget the root, bass player's got that, grab an F below middle C, the B and the E above middle C. The F and B are the Tritone of G, the E is the 13th. The three most important notes played in the grand comping tradition of less is more.

And, when ending the tune, the swing players often automatially played that M6 chord there.


--Mac