As a musician, Mr. Duke made forays into the avant-garde rock of Zappa, Brazilian jazz and urban funk. His long string of recording credits included keyboard work on Jackson’s 1979 “Off the Wall” album and records by jazz saxophonist Sonny Rollins and trumpeter Davis.
In the 1960s, Mr. Duke studied trombone and string bass at the San Francisco Conservatory of Music while playing piano in his own jazz trio in clubs at night. The group’s engagements included a stint as the house band with singer Al Jarreau at San Francisco’s Half Note club.
Mr. Duke also struck up a partnership with French violinist Jean-Luc Ponty, and the two recorded an album in 1969 and gave a series of performances in the San Francisco area that drew the attention of Zappa and the jazz saxophonist Julian “Cannonball” Adderley.
In the next decade, Mr. Duke divided his time between playing organ and synthesizer on tours with Zappa’s rock band, the Mothers of Invention, and playing electric piano in Adderley’s jazz group. Starting in 1976, he co-led a jazz fusion group with drummer Billy Cobham, a noted Davis collaborator.
In the studio, Zappa pushed Mr. Duke to use the keyboard synthesizer in new ways, even to imitate the string bends of a guitarist.
“Bend notes! I’m a piano player,” he once said. “Now I can be like [blues guitarist] Johnny ‘Guitar’ Watson. I could play the blues on a synthesizer. I said, that’s it!”
Mr. Duke appeared on nine albums by Adderley and at least 13 by Zappa, including “Roxy & Elsewhere” (1974). When he wasn’t touring with Zappa, Adderley or Cobham, Mr. Duke led and recorded prolifically with his own fusion band.
Mr. Duke said he had wearied of fusion by the late 1970s.
“I felt that had I played as many notes as I could play,” he later told The Washington Post. “I was tired of looking out from the stage and seeing mostly men. . . . The fusion shows attracted mostly men, because it’s male-driven music. Ladies like softer, groove-oriented music. I was wondering if I could draw a different kind of audience with a different kind of music.
“The turning point happened right there in Washington, at the old Cellar Door,” he said. “Ndugu [drummer Leon Chancler] started playing this beat and I liked it so much that I told Byron [bassist Byron Miller] to start playing along to it while I added something on top. We called it ‘Reach for It’ and it became the title track of our next album.”
“Reach for It,” a dance groove that could have come from George Clinton’s Parliament, reached No. 2 on the Billboard rhythm-and-blues charts in 1978 and considerably broadened Mr. Duke’s audience — even as it alienated more than a few of his fusion fans.
Another funk-oriented hit, “Dukey Stick,” followed that same year. Some thought the title referred to the mini-Moog keyboard synthesizer that he wore around his neck, but Mr. Duke insisted that it referred to “a magic wand in the tradition of ‘Star Wars.’ ”
In the 1980s, Mr. Duke branched into production work, much of it far afield from jazz and fusion. His many successes included such rhythm-and-blues hits as a Taste of Honey’s lush 1981 remake of the Japanese pop hit “Sukiyaki,” Jeffrey Osborne’s “Stay With Me Tonight” (1983) and Deniece Williams’s “Let’s Hear it for the Boy” from the 1984 movie “Footloose.”
Regarded as a perfectionist in the studio, Mr. Duke also knew how to cut corners when necessary.
“Many of Taste of Honey’s vocals were done right in this office,” he told Musician magazine in 1984. “We came in to save money, moved the couch out, set the microphone right here and recorded. For Jeff [Osborne]’s first record, we had to turn the refrigerator off, take the clock out for the ticking and put foam in the windows to keep the birds and dogs from coming through.”
The Dianne Reeves album “In the Moment — Live in Concert,” produced by Mr. Duke, received a 2000 Grammy Award for best jazz vocal album. His other production credits included recordings by the Pointer Sisters, Barry Manilow, Smokey Robinson, Melissa Manchester, Gladys Knight, Anita Baker and the gospel group Take 6.
George Duke was born on Jan. 12, 1946, in San Rafael, Calif. He began taking piano lessons at 4 after his mother took him to see a performance by bandleader and pianist Duke Ellington.
“I don’t remember it too well . . . but my mother told me I went crazy,” Mr. Duke said on his Web site. “I ran around saying: ‘Get me a piano, get me a piano!’ ”
Mr. Duke held music degrees from the San Francisco Conservatory of Music and San Francisco State University.
While studying at the conservatory, Mr. Duke recorded his first album, “The George Duke Quartet Presented by the Jazz Workshop” (1966) for a German record label.
“Without a doubt, this is the worst record I’ve ever made,” he later wrote. “I was quite nervous and had been studying John Coltrane. For some reason I thought all I had to do was play the head of a tune real nice and then proceed to rattle off myriads of notes at high velocity. This did not make for a pleasing result, but it was all I knew.”
His wife, Corine Salanga, died last year. They had two children, but a complete list of survivors could not be confirmed.
In later years, Mr. Duke expressed frustration with the younger generation of hip-hop acts that sampled his recordings.
“The younger artists have all come up on machines,” he told the Los Angeles Times in 1999. “They didn’t work with their heroes, they sampled them. Now when they run out of music to sample — and they will; they’ve sampled ‘Reach for It’ at least 20 times already — then what are they going to do?
“They need to go back to the people who know how to create,” he added. “There needs to be a handshake between them and us.”