Watch the Riff #1 online guitar lesson by Brad Carlton from Guitar Lab: Power Chord Blues Riffs
Chart number one shows the changes for the 12 bar blues progressions that will be your backing tracks. Both of these are in the key of A. Notice that progression number one is very basic. It does not have a quick change and also does not end on the V7 chord. Progression number two has the quick change (the IV7 in measure two) and it ends in measure 12 with the V7 chord. Chart number two shows various rhythmic options over a shuffle feel. I will demonstrate these so that you'll see how you can get a lot of mileage out of one riff. For this lesson you will be using example 1 which is simply an A5 on the first and second strings. Remember that you can play these notes together or arpeggiate them.