We see Bono's face before we hear a soul singer sing, but other than that prizing of current fame over timeless R&B, Greg "Freddy" Camalier's engaging new doc Muscle Shoals stands as a winning tribute to the northern Alabama studio, whose musicians and engineers laid down some of the greatest pop tracks of the late '60s and early '70s: Wilson Pickett's "Land of 1,000 Dances," the Staple Singers' "I'll Take You There," and Percy Sledge's "When a Man Loves a Woman," for starters. The film and its principals — FAME Studios founder Rick Hall, Jerry Wexler, members of the rhythm section, even Aretha herself — indulge in myth-making, citing some spirit hauled up from Alabama river mud that made these white musicians play so "greasy" and "funky" (Aretha's words!). But with music this rich and soulful, a little grandiosity is to be expected — especially considering that the studio was so egalitarian about race at a time and in a place you wouldn't expect. The archival footage is strong, Camalier is generous with musical clips, and the talking heads generate some drama when describing epochal moments like Aretha's first session. We don't really need Mick Jagger or Alicia Keys to tell us how good "I Never Loved a Man the Way I Love You" is, of course. Much more persuasive is seeing Muscle Shoals keyboard player Spooner Oldham, all these years later, hitting the opening organ chord: It's all mud, spirit, glory and everything else. It's such a high that the Rolling Stones later talking us through the recording of "Wild Horses" and "Brown Sugar" feels like a bit of a letdown. Still, the Lynyrd Skynyrd section might even make you hear "Free Bird" with fresh ears.