In 1991, German hardcore band Bohren & Der Club Of Gore made the radical decision to shed the shackles of the style they'd been playing for four years in favour of slow-moving, jazz and ambient inflected instrumental music. Since then, they have released eight albums, usually separated by three-to-four year gaps, but each containing exquisitely snail's pace sonic constructions dominated by echoing piano, gently brushed drums, gently grinding bass throbs and mournful saxophone. Each album builds patiently, with every track a slow-burning capsule of melancholic atmosphere, and latest salvo Piano Nights is no exception. The title suggests a focus on the piano over the other instruments, a subtle shift that makes it possibly their most evocative album in years. The Quietus caught up with multi-instrumentalist and keyboardist Morten Gass to discuss the album, along the way learning that Bohren don't see themselves as making dark music, compare their sound to elevator ambience and - perhaps surprisingly - don't really consider their music in jazz terms.

Could you please provide me with a bit of background on the development of Piano Nights?

Morten Gass: It was three or even four years in the making. We put a lot of patience and research into the record, looking at studio techniques and instruments to get the easy listening sound that this album has. The title, Piano Nights, came first, as always with our records. We think of a title and then come up with the music for that title. It's like a kind of theme, and this was the same with Piano Nights. So we needed a piano [laughs].

The title suggests the piano sits at the heart of the album. What drew you to taking this route?

MG: The album is not really based around the piano sound, it's just in the title. We chose a piano because we always wanted to use a vibraphone, which we'd used before but you couldn't really distinguish the sound between the Fender Rhodes and the vibraphone. It's almost the same sound. That's the main reason why we used the piano, and on this album, we actually used an acoustic piano.

Piano Nights has been described as your best album since Black Earth, which many consider to be your masterpiece. Would you agree? Do you have favourites among your albums?

MG: Favourites… [laughs]. Musicians always say "our last record is the best", and for me it's the same. We didn't say that this record is as good as Black Earth, it's something that record companies write to sell more records, I think. We never would describe the album in that way, it would be silly.

One word often associated with Bohren & Der Club of Gore is "dark", and this album has titles like 'Ganz Leise Kommt Die Nacht' ('Quiet Night Is Coming') and 'Fahr Zur Hölle' ('Road To Hell'). Do you think of yourselves as making nocturnal or dark music?

MG: That's a tough question. We never think of ourselves as making dark music, it's beautiful music, and you can listen to it at night. That's maybe right, but is it dark? I don't know. What's dark music? It could mean goth music for some people, for others it's black metal, and some think an album is dark because the artwork is dark or the musicians have black fingernails. It's nice, warm music, and for me dark music is cold. In the end, it depends on the listener.

For me, the mood [of this album] is the same as on other records. Maybe it's because of the sound of the record, which I would describe as "easy listening", more than the other records. It's more James Last than the other records [laughs].

Although it's almost always purely instrumental, there is an emotional resonance to your music. Do you seek to convey certain feelings and thoughts through your music?

MG: We have no lyrics, just titles, and I like it when things are abstract. I don't want to tell a story or force anyone towards a certain story. Everyone can do with the music what they want. That's why it's instrumental music in the end. When we write the music, we have a sort of theme, because we have the title. There are pictures in our minds when we think of a title, and the other guys in the band know in which direction we want to go with the music if we've got the title first. It is important, but not so much for the listener.

How do you compose and record your albums? Is there an element of improvisation at play?

MG: There is no improvisation. Like I did 30 years ago, playing on the guitar and getting to a riff, we play on the keys of the organ, vibraphone or piano, each of us at home, and come up with cool riffs, which we put together and make a sound. We make demos, and when everyone's happy with a demo, we record it in our own basement studio, in a painful way.

I'm always amazed at the pace of your albums. Everything advances with incredible slowness and patience. Was that conscious decision from the start?

MG: It was our aim from the start, to play slow music, albums that feature only ballads. I've always liked ballads, and it's a pity that every record only features one or maybe two.

Is it hard work to play so slowly?

MG: Of course, we don't jump around! You need to concentrate and be a bit focused. On the other hand, you have lots of time to think about the next chord. But you have to concentrate on the music. If you play a wrong note, it lingers for ten seconds, and the audience will notice.

Interestingly, although your music is based around familiar instruments: guitar, bass, drums, sax, piano, people seem to find you very hard to define. I've heard you called dark ambient, post-metal, doom jazz, even… Do you think any of those or other terms apply? If not, how would you define your music?

MG: That's a good question. We describe our music right now as elevator music [laughs]. That's more a joke, but somehow it's true. We try to be a bit original, we don't want to be copycats, so it's hard to describe the music because it's a little bit weird. But, for us, it's a good thing that it's not so clear what style we play and that we don't belong to a specific music scene. A black metal guy can listen to us, a jazz or pop guy can too.

You mentioned wanting to a band that only plays ballads, and your music makes me think of classic ballads like 'Love and Hate' by Jackie McLean and John Coltrane's Ballads album. How do you think you fit into the jazz tradition, if at all?

MG: Hmm, the jazz tradition… It's hard for us, because we're not so much into jazz at all. We like the sound of jazz music, but we don't like what they play. They're all such good players, and we're such bad players! We came from a hardcore band and we're not masters of our instruments. We can play the way we do, so to describe our music as jazz would maybe be over the top. We understand why people make the connection, because we use the same instruments, which was our aim at the beginning, but I don't know if it's really jazz music. A real jazz guy would maybe laugh at our music.

Could you please tell me a bit about your background as a band? How did you come to evolve from a hardcore band into what you are today?

MG: We didn't want to just cover other bands that we liked, we wanted to make something of our own. In about 1991, we chose to make something different. We were into so many other types of music, such as Sade and Chris Isaacs and even Detroit techno, so we thought "let's make our own music". We weren't fed up with hardcore or metal, but for us it was boring to play that stuff, because we never reached the same level as our idols. It was fun to play, but there was no real joy for us. It wasn't that much of a shift, really. We don't play chart-friendly music. It's underground, and just a few people like it. The only difference is the pace of the music.

Your previous record, Beileid, included one track, 'Catch My Heart' with vocals by Mike Patton, which was a first for Bohren & Der Club Of Gore. Is this a direction you might explore further?

MG: No, no. As you can see with Piano Nights, we don't want to use vocals again. I see that as a kind of remix album, you know? Some people add breakbeats under their music, whereas we thought "let's do something with vocals". We always had the idea to cover this nice German metal ballad, and that's why we needed vocals. At first, we hadn't thought about Patton, we had someone like Amanda Lear in mind! But the final version was so slow and difficult, we needed somebody a little tougher when it comes to extremes. And Patton has a beautiful voice, and it was an honour to work with him.

In recent years, you seem to be performing live more often. Has your attitude to live shows changed?

MG: No, it's the same as every year. We play around fifteen to twenty shows every year, and have done so for fifteen years or so. Maybe it's because we've been doing more shows in England [that you feel we do more]. We don't like to play more, but we don't like to play less, it's a perfect number. So, as always, we will now play our fifteen shows per year for the next three years. Why not? [laughs]

Bohren & Der Club Of Gore's Piano Nights is out now via Ipecac