NEW YORK • For the legions of musicians, producers and music executives who carefully followed everything The Beatles did, one name on the band's records mattered perhaps just as much as those of the Fab Four themselves: George Martin.

As the producer for almost all of the band's classic recordings, Martin, who died on Tuesday at 90, was an inseparable part of The Beatles phenomenon.

But he also had a vital role in shaping the art of music production and of defining a producer's role in pop music as equal parts technical master and creative enabler.

Martin was not the first star record producer and he did not invent all of the techniques for which he is known. But he may have been the first in the rock era to be viewed as such an essential part of a major group throughout its career and to help consistently push the boundaries of what was possible in the recording studio.

The peak of that experimentation was The Beatles' 1967 album Sgt Pepper's Lonely Hearts Club Band, whose title has become shorthand for ambition in the studio.

Producer and engineer Bob Power has described A Tribe Called Quest's 1991 album The Low End Theory - on which he worked as an engineer and mixer - as "the 'Sgt Pepper' of hip-hop" for its dense and carefully threaded use of samples.

"If you look back to the spirit of record-making from the late 1960s into the mid-1970s, there was so much experimentation," Power said in an interview. "George Martin and The Beatles said that this was not just viable, but this was really the way that we do things, and everyone has continued to view it that way."

In a statement, Rick Rubin - who has worked with artists as varied as Johnny Cash, the Red Hot Chili Peppers and the Beastie Boys - said that "he continues to be the inspiration for those of us striving to make timeless music".

Part of Martin's genius was in the techniques that he and the engineers he worked with developed, or otherwise borrowed. While early Beatles records were full of clever, striking touches - like the complex, ringing chord at the start of A Hard Day's Night - the band's records became increasingly experimental, making use of backward recordings, spliced collages, artificially doubled vocals and instruments sped up or slowed down. The studio itself became an instrument and Martin was, in effect, the master of that instrument, on a level nearly equal with the band.

This concept was new in the early days of The Beatles, when recording engineers wore white laboratory coats and viewed their goal as capturing a live performance with as much fidelity as possible.

But Martin's creative process with The Beatles, and their mutual penchant for experimentation, came to be widely imitated in the pop world as a high ideal of the relationship between producer and artist.

In a statement, Paul McCartney called Martin "like a second father to me" and recalled how they had worked on songs such as Yesterday.

After McCartney brought it to a recording session, intending it for just vocal and guitar, Martin suggested adding a string quartet.

"Oh no, George, we are a rock 'n' roll band and I don't think it's a good idea," McCartney recalled saying. But "with the gentle bedside manner of a great producer", Martin proposed giving the string arrangement a try. Of course, it stuck.

On Yesterday and dozens of other songs from throughout The Beatles' catalogue, Martin acted as a trusted collaborator who sometimes pushed the band into new territory.

The success of their work meant that Martin became inextricably linked with the band. The Beatles' recordings - the band's sole focus after they stopped touring in 1966 - came to serve as a blueprint and a challenge for what could be done in a recording studio.

"The whole procedure was very rule-bound in those days," Peter Asher, the manager and record producer who worked at The Beatles' label, Apple, said in an interview.

"Rapidly, they realised that they had the power to break those rules, and George can take a huge amount of credit for enabling that."

At the same time, Martin "knew exactly how much to interfere and how much not to," Asher added. "I remember visiting sessions when he was in the canteen drinking a cup of tea while the band worked something out, because that was the right thing to do at the time."

NEW YORK TIMES