In July 1966, LIFE magazine published a feature story on the man Frank Sinatra reportedly once called "the only true genius in show business"—Mr. Ray Charles. Whether or not he was the only genius in show business is debatable; but there's no getting around the fact that Ray Charles is one of a handful of the most influential American musicians in history. A prodigious pianist, soulful songwriter and vocalist of astonishing range and power, Charles transformed the pop-culture landscape with his melding of gospel, blues and R&B music during the 1950s.
In 1966, Charles's career was on the rebound after a forced hiatus in rehab the previous year for his longtime heroin addiction. (He'd been arrested for possession — for the third time—in 1965, and agreed to rehab in order to avoid jail time.) After getting clean he reemerged with hits like "I Don't Need No Doctor," "Crying Time" and other songs in various genres, including blues-inflected country, that revealed his powers as an entertainer to be not merely undiminished, but perhaps stronger than ever.
LIFE photographer Bill Ray spent a solid month with Charles during this pivotal time in the singer's career, chronicling performances at celebrated venues like Carnegie Hall as well as hanging out with the legend in the studio, backstage at concerts and on the road and in the air between shows. Here, on Ray Charles' 84th birthday (he was born Sept. 23, 1930, in Albany, Ga., and died June 10, 2004, in California), LIFE.com presents a selection of Ray's photos—many of which never ran in LIFE magazine—that reveal a Ray Charles most of us have never seen.
"I was amazed at how he was able to exercise so much control over so many aspects of his life," Bill Ray says today. "The music, the travel, his love life—which was definitely complicated. He could sometimes seem cool, calculating, even ruthless in his dealings with people, but part of that was a way to make sure he wasn't being cheated, or taken advantage of. To me, at least, he was always very warm, very welcoming. And when he got behind that piano and began to sing—wow! It was just impossible not to be moved by music that powerful."