He’s been considered a guitar deity for generations, and his recorded work has ranged from the blues-rock jams of Cream and John Mayall’s Bluesbreakers to the more textured stylings of his more recent solo work. But his playing almost defines the history of rock guitar playing. Nowhere but on XRT can you savor the spectrum of Clapton’s contributions and influences. Happy Birthday, E.C. Hear this week’s Friday Feature starting with Lin Brehmer’s morning show.