Geoff Emerick, the innovative recording engineer behind some of The Beatles' seminal albums, has died aged 72.
Sgt Pepper's Lonely Hearts Club Band, Abbey Road, Revolver - Emerick helped The Beatles achieve some of their greatest work and won four Grammy awards throughout his career.
His manager William Zabaleta confirmed his death in a video statement on Twitter, saying: "We lost a legend and a best friend to me and a mentor."
Mr Zabaleta said Emerick had suffered from heart problems for a long time and that he had been on the phone to him when he fell ill on Tuesday.
Agent David Maida also posted a statement, saying that "though my heart is broken, you will remain in the hearts of many infinite".
"I am SO blessed to have gotten to know you and hear your wonderful stories along with the many laughs," he said. "YOU were a great man besides you being such an innovator. I am also happy that I called you SIR Geoff Emerick as you will always be a true Knight in my book."
:: Previously unseen John Lennon footage recording How Do You Sleep
Emerick was 15 when he first met The Beatles at London's now legendary Abbey Road studios. He was promoted to the band's chief engineer in 1966 to work on Revolver.
He also worked with Paul McCartney on Wings' 1973 album Band On The Run, for which he won one of his Grammys.
In an interview with Variety last year, he spoke about his highlights working with the band.
"Revolver is a high point because of what it represented," he said. "It led to Pepper. And perhaps the greatest peak of all was the production of A Day In The Life on Sgt Pepper.
"John first played an acoustic version of the song for George Martin, and I heard it and told a colleague, 'Wait until you hear this'. I still had the shivers. And the night we put the orchestra on it, the whole world went from black and white to colour."
:: Lennon or McCartney? The science behind Beatles songs
Giles Martin, son of the famous Beatles producer, said: "RIP @GeoffEmerick one of finest and most innovative engineers to have graced a recording studio. I grew up with him as he worked so much with my father. We have all been touched by the sounds he helped create on the greatest music ever recorded."
Julian Lennon also paid tribute, describing Emerick as "one of a kind".
Denny Laine, co-founder of Wings, said on Facebook: "We received very sad news today, old friend, Geoff Emerick, passed away. Our condolences to his family during this time. Geoff was a brilliant engineer and a fine man."
Abbey Road Studios tweeted: "Legendary EMI/Abbey Road recording engineer Geoff Emerick, has sadly passed away at the age of 72. We are hugely honoured to be part of Emerick's story and we are committed to ensuring his legacy lives on at the studios."
Liverpool's Cavern Club said: "It is with sadness that we wake to the news that Geoff Emerick has passed away. Thoughts are with his loved ones at this time."
Emerick had reportedly been scheduled to give a US talk later this year to celebrate the forthcoming reissue of The White Album.