LOS ANGELES (AP) — Phil Spector, the eccentric and revolutionary music producer who transformed rock music with his “Wall of Sound” method and who later was convicted of murder, has died.

He was 81.

California state prison officials said he died Saturday of natural causes at a hospital.

Spector was convicted of killing actress Lana Clarkson in 2003 at his castle-like mansion on the edge of Los Angeles.

After a trial in 2009, he was sentenced to 19 years to life.

Decades before, Spector had been hailed as a visionary for channeling Wagnerian ambition into the three-minute song, creating the “Wall of Sound” that merged spirited vocal harmonies with lavish orchestral arrangements to produce such pop monuments as “Da Doo Ron Ron,” “Be My Baby” and “He’s a Rebel," according to The Associated Press.

He was the rare self-conscious artist in rock’s early years and cultivated an image of mystery and power with his dark shades and impassive expression.

Bruce Springsteen and Brian Wilson openly replicated his grandiose recording techniques and wide-eyed romanticism, and John Lennon called him “the greatest record producer ever.”

The secret to his sound: an overdubbed onslaught of instruments, vocals and sound effects that changed the way pop records were recorded. He called the result, “Little symphonies for the kids.”

By his mid-20s his “little symphonies” had resulted in nearly two dozen hit singles and made him a millionaire. “You’ve Lost That Lovin’ Feeling,” the operatic Righteous Brothers ballad which topped the charts in 1965, has been tabulated as the song most played on radio and television — counting the many cover versions — in the 20th century.

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