Oscar-winning soul singer Isaac Hayes who, along with Al Green, James Brown and Stevie Wonder, was one of the dominant black artists in the early 1970s, died in Memphis on Sunday. He was 65.

His friend and former manager, Onzie Horne, told Reuters he spoke to Hayes' wife, Adjowa, who confirmed that Hayes had died.

Hayes, who once told Reuters that he was a "health fanatic," was reportedly found unconscious near a running treadmill at his home. He was rushed to a hospital where he was pronounced dead. The cause of death was not known. In early 2007, Hayes suffered a stroke.

The Rock and Roll Hall of Fame inductee enjoyed two distinct musical careers, first as a session musician, songwriter and producer at the Memphis soul label Stax Records, where he worked primarily with Sam and Dave; then as a solo artist whose lushly orchestrated albums were some of the first concept works by a black artist.

"He was a real powerhouse in music," Don Cornelius, the founder of the "Soul Train" TV series, told Reuters. "He took black music to another level, made it more classic."

The deep-voiced performer was the first black composer to win the Oscar for best song, with 1971's "Theme from 'Shaft,'" an irresistibly urgent mix of wah-wah guitars and hi-hat cymbals spiced by the famous line, "They say this cat Shaft is a bad mother-/Shut your mouth!"

STAX STAR

Hayes, born August 20, 1942, in Covington, Tennessee, was raised by his grandparents after being orphaned. He joined Stax in 1963, and often subbed for the label's primary keyboardist, Booker T. Jones.

He eventually teamed with lyricist David Porter to write and produce songs for the soul duo Sam and Dave, including "Soul Man" and "Hold On! I'm A Comin'."

Hayes told Reuters in 2005 that he came up with the introductory horn line for the latter tune while Porter was in the bathroom. He yelled at his collaborator to hurry up, and so Porter barreled out with pants around his ankles, yelling the words that would become the song's title.

With his shaved head, dark shades, extravagant clothing and plentiful jewelry, Hayes was groomed as a star by Stax executives. He released his debut album, the poor-selling "Presenting Isaac Hayes," in 1968. He broke through the following year with "Hot Buttered Soul," which contained just four songs but sold over a million copies.

Chastened by his unsuccessful debut, Hayes took artistic control of the follow-up. Even though he was a successful songwriter, three of the four tunes were covers that he reinvented, including an 18-minute version of Jimmy Webb's "By the Time I Get To Phoenix."

Hayes' work on director Gordon Parks' urban crime drama "Shaft," a project he had hoped to star in, was the first of many forays into movie soundtracks. He got in front of the camera for the 1974 cult classic "Truck Turner" and kept busy with film work. He had a cameo role in an episode of "The Bernie Mac Show," whose star died on Saturday.

Hayes left Stax in a dispute over royalties in 1975, the year the faltering label went bankrupt. He filed for bankruptcy shortly thereafter and lost all his songwriting royalties.

In his later years, Hayes reached a new audience by supplying the voice for Chef, the libidinous sage on the cartoon series "South Park." But he left the show a few years ago because he disagreed with its attacks on Scientology, the religious movement to which he belonged.