If there's an undercurrent to modern American rock, then Sebadoh have glided awkwardly along it for the best part of a decade. When the Boston-based band lurched into existence in 1989, American alternative rock was just beginning to reach a wider audience; The Pixies were mischievously blending pop and punk, and REM were signing a long-term deal with Warner. By the time Sebadoh had released their third album on the Homestead label, Nirvana had smashed through to the mainstream, selling six million-plus copies of Nevermind, and kick-starting the craze for grunge which saw Pearl Jam, Soundgarden and Stone Temple Pilots replace older rock heroes like Rush, Journey and AC/DC in the hearts of white American teenagers.

While Sebadoh's Lou Barlow was chipping away at his craft for the first part of the 1990s, Kurt Cobain was becoming an icon for alt-rockers everywhere, a self-destructive hero who came from the sticks and headed straight for the spires of rock'n'roll excess. Everybody wanted to know what shirts he wore, what drugs he took, and who was his favourite band. The fans knew already: he preferred plaid, chose heroin, and listened to Sebadoh. Thus did lumber shirts gain an anti-fashion cachet, smack reach semi-respectability, and a lo-fi trio from Boston achieve a certain fame-by-association. Sebadoh subsequently signed to Sub Pop, Nirvana's original label, then set about proving their worth through albums such as Bubble And Scrape and Bakesale, reaching a kind of credibility plateau just around the time Cobain killed himself.

Now, in 1999, the American rock landscape has changed again: the musical terrain has been levelled by an array of dull, bluesy, corporate acts such as Counting Crows, Hootie & The Blowfish, Matchbox 20 and The Dave Matthews Band. Pock-marking this flat horizon, however, is a newly-matured crop of alt-rock bands who have survived the grunge wars. Mercury Rev have emerged to produce the best American rock record of last year, while lofi alumni Pavement have grown into a 10-storey block of solid creativity. And now Sebadoh are about to stomp into focus with their new album, cheekily-entitled The Sebadoh.

Lou Barlow is on the phone from Louisville, Kentucky, home of his two band-mates, bassist/vocalist Jason Loewenstein and new drummer Russ Pollard, who has replaced sacked drummer Bob Fay. Barlow himself has, in recent years, chosen to live in the glitzy environs of Los Angeles, a move which might be seen by hardcore 'Doh fans as a bit of a geographical sell-out. They needn't worry, because Barlow is not about to become lofi's answer to Courtney Love, even though the new album will certainly get him recognised round Malibu way. With Sebadoh on the verge of striking gold after years in the wilderness, it would appear that every underdog has its day. "If you keep plugging away at it, eventually people will listen," says Barlow. "I guess that's where the authenticity thing comes in. If you're pretty honest about what you're doing and there's some kind of integrity there, then people will pick up on it." It worked for REM, and they kept their integrity through massive commercial success. Sebadoh's eventual success, however, might leave some of their hardcore fans feeling betrayed.

"I think it's really personal - it's really more up to the listener, because people have different ideas about how a band would betray them. I've found that, throughout our history, on every tour we've ever done, there's always somebody who comes up and starts telling us how we've betrayed them."

Should the inevitable happen, and Sebadoh find themselves looking down the barrel of commercial success, how will Lou Barlow react? "I think I probably care less about that this time than I ever have. I don't really even know if the album is going to be a success. I just know that we worked hard on the record, and we're finally getting to a point where we're taking control. We probably put more of ourselves into this record than we ever have. But that doesn't mean automatically make it great - the next record we make, we might do even better. In fact, while we're rehearsing and playing the live shows, I'm starting to see where we can take it in the future. This album doesn't feel like an end - it feels more like a beginning to me."

Did he feel that control was slipping out of his grasp, and that Sebadoh were in danger of sinking into that grungy mire of unfulfilled potential? "A little bit. When we were recording the last album, we were working with some people who thought they had a better idea than us what we were supposed to sound like. And myself, Jason and Bob couldn't really get a united idea about what we wanted out of a record. So it just slipped into someone else's hands, and that carried over into the touring, and even though we had a good time and everything went well, there was still a feeling that we had been compromised a little too much."

One casualty of Sebadoh's crisis was drummer Bob Fay; replacement drummer Russ Pollard, however, has added a new, soulful dimension to the Sebadoh sound, which is apparent on the funk-punk rhythms of It's All You, Weird On The Way and the current single, Flame. Barlow and Loewenstein, meanwhile, seem to have found a near-perfect balance between their two discrete song-writing styles.

"It's working really well right now," agrees Barlow. "Somehow we always manage to give each other just enough space to do what we need to do. You know, it's something that really has a lot of potential to grow, which is probably the most important thing to me. Each time it's just a little bit of a compromise, and also a desire to see a friend do well and expand. We write separately a lot - when you're doing stuff like lyrics, and you want to make them really personal, that's something you need to do. "But more and more when we're putting the records together, we all work together on the texture. Jason really had his shit together when it came down to doing this record, whereas I really didn't, so I needed more help from Jason and Russ this time."

Barlow has an excuse for being untogether - he's also working on material for his successful side-project, Folk Implosion. When his hobby band had a surprise US hit single with Natural One, from the soundtrack of the movie Kids, Barlow has found himself a most unlikely entrant in the Billboard Hot 100. How did it feel to have sudden chart fame under another name?

"I just kinda shrugged my shoulders and said, hey, that's cool. I knew it was me, but it didn't freak me out as much as it freaked everyone else out."

Success in rock does seem to scare a lot of people - they see rock music as some kind of hard drug which might suddenly take control of them and destroy them. "Yes. That was the conversation I had with my partner in Folk Implosion. I was telling him, look, dude, we're really in control. I guess I've just learned this from playing live and being in a band for 10 years. It isn't going to destroy you. The people who fall prey to that myth are the people who ask for it. I mean, even Kurt Cobain asked for it in his own way too. He put a lot of his own negativity and ambivalence into his music, and whatever you put in your music you get back. And it can be a little bit overwhelming.

"I felt a little regret about Kobain's death, and I felt bad that he didn't have people around to remind him that it was really all about the music. It also underlined more of the negative parts of his music rather than the positive parts. But it didn't really affect my motivation or ambition. It just made me realise how much you have to watch what you say in your music, because it'll eventually come true. If you keep writing songs about guns and being depressed, eventually it'll catch up to you. It was a testament to the power of the music that that happened to him."

One of the negative legacies of Kurt Cobain's death is that any American music which sounds remotely grungy or lo-fi is now automatically assumed to be nihilistic. Listen to the grinding optimism of Sebadoh tunes such as Colorblind, Thrive and Nick Of Time, however, and you'll realise that lo-fi need not necessarily signify a low ebb. Has so-called "complaint rock" given alternative music a bad name?

"Well, its bad name is not thoroughly undeserved," laughs Barlow. "I think there is a sort of inherent negativity to it all. It's because we're all influenced by punk bands like Black Flag and record labels like SST, where it was all about wearing your street clothes and not getting sucked into the machine. And there was always a certain negativity and lack of ambition there. Even the indie mentality is obsessed with failure, and I don't want to be a part of that. I want to focus on what I want, and how I want to develop. And if the band gets more popular, I'm already prepared for when that happens. I'm ready for it. I've been doing this for so long, the survival technique is engrained in me."

Sebadoh play the Mean Fiddler in Dublin tomorrow night (Saturday January 23rd). The Sebadoh is released next month.