“Does anybody feel like hearing the blues?” Aretha Franklin asks, introducing “Dr. Feelgood.” She actually had to ask: At the time, San Francisco venue Fillmore West was more famous for bringing rock acts like Jefferson Airplane. Earlier in her set, she even covered Simon and Garfunkel to some chatter. But by then, the crowd answered with a resounding yes — and Franklin’s reply is well worth hearing. In “Dr. Feelgood,” she throws her head back in an ecstasy that sounds both sexual and religious. And for a reprise of “Spirit in the Dark,” Ray Charles appears, even though he wasn’t set to perform. He was only there to watch. “If you listen to the record, you can tell I don’t know it,” he told Rolling Stone in 1973. Christina Lee