Norman "Hurricane" Smith, engineer for the Beatles, producer for Pink Floyd and Pretty Things, also had his own, later in life music career. Here's a clip from the Johnny Carson show (classic '70's television!).
My first concert was Alice Cooper at the Music Hall in 1972 (my first was supposed to be CCR at a gymnasium in Maine circa 1969 but that's a story for another day). Not sure where that Alice Cooper stub ended up but here are some I could locate.