George Martin, the Beatles’ urbane producer who quietly guided the band’s swift, historic transformation from rowdy club act to musical and cultural revolutionaries, has died, his management said Wednesday. He was 90.

Manager Adam Sharp said in a statement that Martin “passed away peacefully at home” on Tuesday evening.

Martin was too modest to call himself the “fifth Beatle,” but Paul McCartney said Wednesday that “if anyone earned the title … it was George.”

“He was a true gentleman and like a second father to me,” McCartney said.

Martin produced some of the most beloved songs and most popular and influential albums of modern times — “Sgt. Pepper’s Lonely Hearts Club Band,” ‘’Revolver,” ‘’Rubber Soul,” ‘’Abbey Road” — elevating rock LPs from ways to cash in on hit singles to art forms, “concepts.”

From a raw first album in 1962 that took a day to make to the months-long production of “Sgt. Pepper” just five years later, Martin would preside, assist and sometimes stand aside as the Beatles advanced by quantum steps as songwriters and sonic explorers.

They composed dozens of classics, from “She Loves You” to “Hey Jude,” and turned the studio into a wonderland of backward tape loops, multi-tracking, unpredictable tempos, unfathomable segues and kaleidoscopic montages. Never again would rock music be defined by two-minute love songs or guitar-bass-drums arrangements.