Watch the Octaves online guitar lesson by Jeff McErlain from Blues Guitar Survival Guide - Lead
Soloing with octaves is a great devise to use to add some variety. They can be a bit tricky to slide around so practice is definitely in order. The most famous guitarist associated with soloing with octaves is Was Montgomery. Wes played with his thumb instead of a pick and that added to his big round tone on the octaves. I will often do this as well as a tonal option. My first introduction to octaves was Hendrix's Third Stone From The Sun. The melody is played in octaves, he also uses them in the amazing Machine Gun from the Band of Gypsys recording. I have to mention that track in all my courses as I believe it is one of the single greatest pieces of recorded music. Ever. In the history of anything.