Ahead of the release of their new song ‘Now and Then’, the Beatles have given fans a 12-minute-long documentary on the story behind it.

In the documentary, Paul McCartney explains how they used John Lennon’s voice from a ‘muddy’ cassette from the ’70s. Using Peter Jackson’s state-of-the-art technology, they were able to pull the track apart before isolating Lennon’s vocals. It was here they were able to build the song.

“They said, this is the sound of John’s voice. A few seconds later… there it was. John’s voice, crystal clear… Peter took John off and gave him his own track. It’s like John’s there, you know — it’s far out,” McCartney said of the process.

“In the mix, we could lift John’s voice without lifting the piano, which had always been one of the problems. Now we could mix it and make a proper record of it. I pulled it out, had a listen to it, and thought, ‘Oh, I could actually do the bass a bit better. So why don’t I start there?’”

In a statement about the documentary, writer-director Oliver Murray said, “The legacy of the Beatles set one of the most important foundations for modern youth culture. It is a great honour to be given the responsibility of telling this story and I think it will conjure up a lot of different emotions for people as we all have a very personal relationship to the band’s work. ‘Now And Then’ is a story of musical archaeology and a brotherly bond between four guys that gave the world some of the most popular entertainment in history.”

The doco kicks off a massive 10-day rollout of Beatles material on YouTube and Disney+.

‘Now and Then’ will be released, along with the music video, at 1am AEDT, Friday November 3.

On Friday morning, Clairsy & Lisa will play the track during Breakfast, however there’ll be plenty of opportunities to hear it on 96FM over the weekend.

November 10 will see the expanded versions of the ‘1962-66’ and ‘1967-70’ collections, featuring dozens of new remixes, will hit digital platforms and retail stores.