It's a tale of two CDs for Foo Fighters, whose new album is a double-disc affair which juxtaposes the band's loud/heavy/giving-it-loads sound with a more ambient, acoustic approach. Frontman Dave Grohl and bass player Nate Mendel tell Brian Boyd how the band got in touch with their gentler side

'YOU can't turn up at a rock festival with a harpsichord." It was for this reason, and this reason only, that Dave Grohl had to have a major rethink when recording Foo Fighters new album. "It was going to be an acoustic album," he says. "I was really pissed off with the last record (2002's not very good One By One). Only about four of the songs were any good. It was something we had rushed into. I spent a year and a half screaming my ass off on stages during that tour, so I wanted this one to be an acoustic album - except that we're the Foo Fighters, so we'd have to disguise it as a film soundtrack or something. But then the songs we did sounded so beautiful - they were still a bit like a film score, but they actually did sound like the Foo Fighters, except a lot quieter. So yeah, it was going to be acoustic, but then I suddenly realised - I can't turn up at a rock festival with a harpsichord - this band just has to make some rock music. so we made it a double album."

Bass player Nate Mendel adds that it was doing record shop in-stores that facilitated the acoustic approach. "For some reason we had a lot of in-stores on the last tour and instead of lugging in all our gear, we just decided to do it acoustically. And we loved it. And then we realised that we could actually do an album like this, but there was always the harpsichord problem. Given that we were going to make a double, we went to extremes and eliminated the middle ground. The quieT album is really delicate and atmospheric and the loud one is brutal and aggressive."

The album is called In Your Honor - a title dedicated to Democratic presidential nominee John Kerry. "I spent time on the campaign trail with him last year," says Grohl. "We'd pull into small towns and thousands of people would come to be rescued by this man. It's by no means a political record, but what I saw on that campaign inspired me, so that's where we got the title. The only reason I was on the John Kerry campaign is because George Bush was using a Foo Fighters song at his rallies - which just goes to show how out of touch the man is if he's using our songs. The only thing I could do by way of retaliation was to go out and play the song myself at John Kerry rallies."

For Grohl, having been so dissatisfied with the last album and this year marking the 10th anniversary of Foo Fighters' formation, this - their fifth album - had to be a career-defining effort. "We were in a quandary about what to do next and that's why the whole quiet/loud thing was so appealing," he says. "I knew we were capable of both - we've done 'quiet' before, but even I was surprised by just how beautiful we could get the music to be on the quiet one. By the way, we don't call it the acoustic album, we call it the quiet one. That's because it's not entirely acoustic and also because that term just has a bit too much baggage for me."

Foo Fighters began as a bunch of demo tapes that Grohl had recorded while still the drummer in Nirvana (his song-writing credits with Nirvana were restricted to one co-write and one B-side). Grohl played everything on the band's 1995 eponymous debut before drafting in the rhythm section of the original emo band, Sunny Day Real Estate. Numerous personnel changes later, the band now has a fixed four-piece line-up.

As some indication of how seriously the band took the double album, they actually bought a warehouse in Los Angles, built their own studio in it and gave themselves a six-month deadline to complete both albums.

The loud album was recorded first. "Knowing we were going to have a quiet one also, we wanted the loud one to have songs that made people beat the shit out of each other the first time they heard them. We really took out the middle ground," says Grohl. Certainly, the loud opener - and first single - Best Of You is a tooth-rattling onslaught with Grohl screaming "I swear I'll never give in" over a ferocious sonic attack.

For the quiet album, the band drew up a wish-list of guest musicians, as Nate Mendel explains: "On the loud one, there was no need to get anyone in - it's what we do best as a band - but on the quiet one we had a list of names we wanted to get in to play with us. On the list were: Norah Jones, John Paul Jones (Led Zep bass thumper), Grant Hart (ex of Hüsker Dü) and Ry Cooder. As it turned out the last two were unavailable, but Norah came in and did vocals and piano on a song called Virginia Moon and she was just so awesomely professional. We also got in Josh Homme from Queens Of The Stone Age to do this really beautiful duelling acoustic guitar thing on the closing quiet song, Razor, and then John Paul Jones, who was in town picking up a Lifetime Achievement Grammy came by to play piano and mandolin. Dave was as excited as I've ever seen him recording with John Paul Jones - he's a total Zeppelin freak."

"I've been obsessed with Zeppelin since I was a child. Having their bass player turn up to play on our record was probably the musical highlight of my life," says Grohl.

Mendel doesn't feel the Foo Fighters' core fanbase will be that put out by someone such as Norah Jones appearing on the album. "There are some other thumping rock bands whose fans might be a bit disturbed by her inclusion, but not the people who like the Foo Fighters," he says.

One would have thought that the quiet album would have been more difficult to arrange and produce than the loud one, but Mendel says it was almost the other way around: "In terms of playing the songs, the loud one was easier as you don't have to be so precise. What people may not realise, though, is the energy dynamic is very complicated on loud rock albums. There are a lot more peaks and valleys to deal with in the production, whereas with the quiet album, well, it's only going to get so loud," he says.

"In a strange way, the different energy of the quiet album dictated how the loud one would sound," says Grohl. "Because it was so hyper-quiet, we decided, on finishing it, to go back and revisit the loud album and really kick the shit out of it. We ended up with two extremes."

For Mendel, the album will be "segregated" when it comes to touring. "For this upcoming tour (which includes a headlining slot at Oxegen on July 10th) it will be the loud album only. There's no way we can mix the two. We do want to tour the quiet one as well, though. Later in the year we're planning to play two shows in each town - with the second show being the quiet album in smaller, theatre-style venues."

"We're going to keep them separate, just like they are on the record," says Grohl. "We'll have to get some additional musicians in to play the quiet songs. You don't want to be playing a big rock festival and midway through whip out an acoustic ballad. People will throw things at you."

Grohl has just recently set internet message boards aflame by stating that he's prouder of Foo Fighters than he is of Nirvana. "I was only the drummer in Nirvana and I was the sixth drummer they had. It's all a bit of a blur to me what happened with Nirvana. I was only in the band for three-and-a-half years and I'm now in the Foo Fighters for 10 years. This band is more personal to me. And this album is our career high."

You told me that three years ago on the release of One By One . . . "I was lying," he says. "You know when people ask you what the best Led Zeppelin album is? Which one you should buy first? And the answer to both those questions is Physical Graffiti. I want In Your Honor to be considered our Physical Graffiti."

In Your Honor is released next Friday

'HEARTBREAKING': DAVE GROHL ON GUS VAN SANT'S LAST DAYS

ALTHOUGH director Van Sant has said his soon-to-be released feature, Last Days is a work of fiction, it is inspired/influenced by Kurt Cobain. The film features the last 48 hours of a blond-haired leader of a grunge band suffering from acute inner turmoil. The film is set in 1994, the year Cobain died.

"I'm not going to go and see it," says Grohl of the film. "These things depress me, they're heartbreaking. The scars have healed a bit, but I'm not watching it. Anyone who wants to know anything about Nirvana - the box set contains the full musical story."

Given the long-running feud between Grohl and Courtney Love, it seems appropriate that the singer's widow has given Last Days her blessing. In another twist though, Van Sant has publicly said that he doesn't think Love should see the film as she may find it "too distressing". He also said that fear of a lawsuit from Love was the reason he made Last Days a work of fiction - only "inspired by" Cobain.