This shape shares some obvious fingering commonalities with the “B.B. box” and is
based on an open A-type barre chord. It has both minor and major connotations.
Mike Bloomfield plays both minor and major 3rds, as well as the 6th, minor 7th, and the flat 5th, in this phrase over the I–V–IV–I chords
and the turnaround of a 12-bar blues in A. His home base in this section is the minor pentatonic scale.
Download Example Audio 1...
Robben Ford stresses the flat 5th with bends and a trill figure in this characteristic phrase in D minor. Notice the shift down into the third
position during the passage in measures 3 and 4—it’s a common extension of the secondary blues box.
Download Example Audio 2...
This lesson comes from:
Blues Guitar Classics