Watch the Example 12 online guitar lesson by Brad Carlton from Guitar Lab: Boogie-Woogie
We're back to four voices in this example. Notice the chords are A5, B5, C5, B5 all over an A pedal tone. A Dorian is the source for these structures. You'll notice a contrast with this example when compared to the last seven examples. Here we have a rather "hollow" sound because of the use of power chords.