Appreciation: George Martin helped bring Beatles revolution

Since four lads from Liverpool changed the world more than 50 years ago, more than one man has claimed the title of "fifth Beatle." But for those whose opinions matter, there was only ever one candidate: George Martin, who died Tuesday at age 90. The elegant Englishman who produced so much of the groundbreaking band's catalog was as central in shaping the music and ensuring its endurance as any other person.

Paul McCartney said so himself of Martin, who gave The Beatles their first recording contract, in a detailed, moving statement that included a memory of the time McCartney brought a little song called Yesterday to a recording session. McCartney's bandmates — John Lennon, George Harrison, Ringo Starr — suggested he sing it alone, accompanying himself on guitar. Martin, a classically trained musician, had another idea: To use a string quartet.

'Fifth Beatle' producer George Martin dies at 90

"I said, “Oh, no, George, we are a rock and roll band and I don’t think it’s a good idea,'" McCartney recalled. "With the gentle bedside manner of a great producer, he said to me, 'Let us try it and if it doesn’t work, we won’t use it, and we’ll go with your solo version."

The rest is history, of course, as are Martin's countless contributions as The Beatles evolved from a pop phenom to a cultural force that redefined and transcended rock. He brought strings in again — a double quartet this time — for Eleanor Rigby. Over the band's relatively short but remarkably productive tenure, he encouraged the artists to experiment with different keys and tempos, as well as textures and pioneering techniques such as playing tapes backwards. His flourishes ranged from the baroque piano solo featured in In My Life (Martin was himself a pianist and oboist, and played on other Beatles tracks) to the marching band in Yellow Submarine to the trippy fadeout to All You Need Is Love, which draws from classical, folk and swing compositions.

While the older, refined Martin may not have shared The Beatles' interests in exploring the lifestyle associated with psychedelia, his genre-defying virtuosity and ingenuity helped make the group's defining adventures in the musical arena possible. He and engineer Geoff Emerick managed to combine two takes of Strawberry Fields Forever to produce the shimmering, hypnotic final track. Martin worked with McCartney to create the 16-minute medley that concludes Abbey Road, a rush of short songs that are alternately poignant, impish, frantic and ultimately exultant.

Celebrities, fans, friends react to death of Beatles producer George Martin

Martin had worked on classical, jazz and comedy recordings (including a Peter Sellers album), before joining forces with The Beatles, and he collaborated with many artists after the iconic group dissolved, including Jeff Beck, the Bee Gees and Celine Dion, who sang Here, There and Everywhere for the 1998 compilation tribute In My Life. Quincy Jones, another revolutionary producer and arranger, called Martin "a true genius in body and soul" in a statement, noting that Martin "knew the secrets of our craft that so few know today."

Jones added, "Thank you for co-inventing the Beatles."