A stark light shines on the empty stage. "Ah," jokes one punter, "the light show." He's not wrong. Shellac don't do light shows, just as they don't do merchandise, major labels or - if they can possibly help it - CDs. This uncompromising approach has helped Shellac linchpin and former Big Black and Rapeman frontman Steve Albini rise to legendary status among fans of the fiercely independent and awesomely abrasive US hardcore movement. Albini is best known to everyone else for his day job as the (often reluctant) producer of the likes of Nirvana, Bush and PJ Harvey. Shellac is how he relaxes.

You wouldn't know it from listening to their music. Albini, Bob Weston (another producer) and drummer Todd Trainer (who runs a hairspray warehouse) produce an impeccably raw sound that stops and starts and spits with defiance. Guitars bark and shriek, drums clatter across the mix and bass turns from anchor to discordant lead instrument. The effect is rather like someone repeatedly and precisely dropping an anvil from a great height, while a regurgitated blues riff weeps inconsolably in the corner.

In the context of this magnificently radical racket, the band's cheerful manner comes as something of a shock. Geeky Albini, chubby Weston and scruffy Trainer look like they could be the protagonists of a new American sitcom. As if to underline the resemblance, Weston uses an interlude to marshal a question-and- answer session and tell the audience a joke about having sex with pigs. Later, all three band members pretend to be aeroplanes.

It means that a rather merry atmosphere underpins these serious songs. It does nothing to lessen Shellac's crusading zeal for noise. Itchy quiet spells erupt into torrents of noise, gloomy poetry is recited over feedback and Albini gouges his guitar into the stage, a look of intense concentration on his face. It's awe-inspiring stuff, and against its backdrop Shellac's unbending radicalism feels utterly justified.

· At the Scala, London N1, tonight. Box office: 08700 600 100.