Blixa Bargeld: Linden leaves and air cake - what kind of music do you call that?

For a man who's spent much of his career summoning up the catastrophic in the service of art, Blixa Bargeld - vocalist, lyricist and chief theoretician behind the band Einstürzende Neubauten - is in an expansive mood. He has, he says, been busy telling lies to the European press corps who, over the past months, have been assembling themselves to welcome Perpetuum Mobile, Neubauten's first studio album since 2000's Silence Is Sexy.

Alas, they are only small-scale fibs relating more to where Bargeld - now transplanted from his native Berlin, the city that spawned both Neubauten and its grand theme 24 years ago, to married life in San Francisco - may actually live. "One of the places I've told lots of people where I live is Shanghai - it's not so improbable. My wife's from there."

One might say that this game of cherchez l'homme is central to Perpetuum Mobile. "Its common denominator is basically change, travel, migration and transgression," considers Bargeld. "There is the change of attitude I have problems describing. It's not a melancholia" - a reference to the prevalent humour in Neubauten's body of work - "because there is no despair. There is somehow hope and perspective, but it is subdued."

One hears as much in the quiet dramas of songs like "Dead Friends (around the Corner)" or "Grundstück" [Ground Space]. (The songs move freely between German and English.) It's an album where partings are noted, and works of mourning made. It's possible that Bargeld's recent exit from Nick Cave's Bad Seeds, after 20 years as their guitarist, plays its part in this. The deep air of contemplation is eerie. Although Einstürzende Neubauten laid down the weapons of mass destruction (the pneumatic drills and sledgehammers that gave their both percussion and their name - collapsing new buildings - so germane and reverberative an edge) some years ago, it signals a move away from old practices.

But unusually for Neubauten, Perpetuum Mobile is not fixed in inspiration or location; its dissident commentary has moved away from the complex layers of Berlin. "Not many of us has his life centred in Berlin now," Bargeld says. "Even Berlin has gone."

One song, "Youme & Meyou" - the title encapsulates Bargeld's liking for Steinian word games - mourns the creeping loss of the singular identity of cities. "There's always a construction site, a Starbucks and yet another Guggenheim," he sings against a low electronic pulse and low cascade of a string quartet. Construction sites, of course, featured heavily in the imagery of Silence Is Sexy, an album which raged against the construction of post-unification Berlin where, said Bargeld, "thick layers of meaningless architecture" smoothed over the past.

This double erasure has produced a dislocation that maybe even Neubauten had not anticipated. So while Bargeld and the band's core members, guitarist Alex Hacke and wild card Andrew Chudy have constantly addressed material transformation in their work (Chudy still constructs instruments: here, olive tins, dried linden leaves and something called an air cake join their more usual line up of compressors, guitars and keyboards), this is the first time Neubauten have taken a substantial look at themselves. With the image of the perpetuum mobile the focus has turned inwards to consider the multivalent relationships that sustain and separate them.

Making the album has been an unusually public process. With guitarist Jochen Arbeit and drummer Rudolf Moser now completing the band, they made the decision to open up their working process to internet supporters. For a one-off payment of 35 euros, over 2,000 supporters at neubauten.org were given free access to recording sessions. In phase one, during which Perpetuum Mobile was developed, 114 hours of live studio work were broadcast and subscribers were rewarded with a CD containing a limited and alternative edition of the album. Phase two, which the site is now entering, will, says Bargeld, be more of a platform for individual and outside projects. It should, as they transform their north Berlin studio into a television suite, encompass possibilities for longer broadcasts and DVD releases.

"People think that the internet project must have been like a Big Brother surveillance, but it wasn't like that," Bargeld says. "The interesting effect was that it injected a lot of discipline into the band: the broadcasts became performances of really concentrated work. It oiled the mechanism of the band and gave us so much more momentum."

But as comments and criticisms streamed in via the band's individual laptops, was the process ever intrusive? Bargeld says not. "There were a very few who were disillusioned seeing the trial and error that goes into making the music: maybe they thought that it sprang, fully formed, from a vacuum - Dummmmmm," he exhales in an exasperated puff that happens to be very close to the German for "stupid".

In fact, many of the supporters became active participants, helping to edit songs. On occasions, it was they who insisted that work should continue on songs that the bad had no faith in. One supporter turned out to be a specialist microphone engineer. "I never had a more intimate relationship," Bargeld says, clearly pleased with the sensitivity with which the instrument captured his voice.

"A mature voice is a nice thing. I had to compile some early Neubauten recordings recently, and it was incredible how much higher my voice was. I heard Blixa aged 21, and now I hear him at 21, plus 23. Can you talk about layers or complexity? I'm looking forward to being as old as Paolo Conte - he has a beautiful voice, with a raspy thing on top of the low end - and hearing more complexity in my voice."

Now Bargeld is ruminating actively. "Leonard Cohen, Bob Dylan, these are interesting, ageing voices. Johnny Cash - oh yes, but his was a profound voice when he was only 30; at the end [Cash died in 2003] it really was the singing of a very old man. Wine people have a vocabulary to describe taste. We haven't established a language to describe nuances in voices: we must work on it."

Perpetuum Mobile was, apparently, an emergency appellation. It had nearly been Luftveränderung, a change of atmosphere, a title that may have expressed the alteration in pressure and tensions. Bargeld gives off a wolfish grin. "The most interesting things are always the changes."

'Perpetuum Mobile' (Mute Records) is out on 9 February. Einstürzende Neubauten play at the Forum, London NW5 (0870 150 0044) on 3 April