Sean Lennon works his No. 1, a 1963 Fender Jazzmaster that he picked up in 2000. It's been re-fretted and outfitted with a bridge and vibrato from Mastery Bridge since, but is otherwise stock. Lennon, son of the late John Lennon and Yoko Ono, has been generating quite a buzz fronting the distinctive psychedelic pop band Ghost of a Saber-Toothed Tiger, which he formed in 2008 with his partner, Charlotte Kemp Muhl. “This is the biggest audience we’ve ever played for,” Lennon told the Mountain Jam crowd.