Dave Grohl thought Sound City studios was ''a dump'' when he first went there.

The Foo Fighters frontman - who spent 16 days in the Los Angeles studio, where greats like Neil Young and Fleetwood Mac recorded some of their best work, to make new documentary 'Sound City: Real To Reel' - first used the studios when drummer in Nirvana and despite its dilapidated appearance, he was staggered by the impressive sound it produced.

Asked his first impressions of the studio, he said: ''The same as anybody else's: that it was a dump. It was 1991 when we walked in the front door, and it looked like it was 1973 inside. When we recorded the first song ['In Bloom'], we plugged in, sat down, recorded the first couple of takes and went into the control room to listen to playback.

''Butch hit 'play', and it was unlike anything we'd ever heard. It was Nirvana, but the biggest, baddest, punchiest version of Nirvana we'd ever heard. It was just like, 'Oh my god! How did that happen?' It was that room and that board.''

The documentary also saw him team up with guests including Sir Paul McCartney for a special soundtrack album, and he described the experience of recording with The Beatles legend as the most ''profound'' moment of his life.

Dave explained to Classic Rock magazine: ''There's a rumour that The Beatles rehearsed in that room before their Hollywood Bowl gig in the mid-60s. This film isn't just about Sound City, it's not just about technology or the human element, it's also an intensely personal story for me.

''The reason I'm a musician is because I fell in love with The Beatles. So for me to be playing with the person who is responsible for me being here right now was about the most profound, full-circle moment of my entire life.''