Watch the Flat 7 Blues online guitar lesson by David Santos from 50 Bass Grooves You MUST Know
This is a 12 bar blues in F utilizing a two bar phrase as a bass line for most of the tune. The main two bar bass line outlines a dominant 7th chord in a quarter note pulse over the course of the 2 bars. The flat seventh note occurs on the downbeat of measure two of the two measure phrase. The five chord and the four chord in bars 9 and 10 break this pattern and outline a major sixth arpeggio because they are only a bar long on this turnaround and there isn't even time to reach the flatted 7th note within each measure. The dominant 7th two bar pattern resumes on bar 11 to finish the form.