"Six shots of Jack Daniel's and fill the rest up with Coke!" shouts the bald teenager, dripping sweat onto the bar. We could only be at a nu-metal gig in Docklands Arena, an inglorious shed in a made-up part of east London. Architecturally at least, it is a graveyard of rock aesthetics.

Korn take the stage while footage on the video-wall backdrop shows a scared child. The drummer mounts his three-storey podium and waves like a triumphant ant. The guitarists launch into a savage fuzzsaw riff, while singer Jonathan Davis, who used to be a student of mortuary science, begins to alternate tuneful barking with nasal raps.

No latecomers to the nu-metal scene (they formed in 1993), Korn are musically more sophisticated than many in the genre. The guitars perform bendy tenor drones, or squealing countermelodies in eastern scales. Sudden changes of ambience furnish dramatic interest, as when sweetly chiming high guitars with murmured rapping, or glassy echoing arpeggios, or even something approaching a jazzy walking bassline, provide moments of respite before the thrash resumes.

In this venue's disgusting acoustic, a lot of the precise riffing - dominated by a clattering, over-equalised snare drum - sounds like generic Slipknot-esque noise. But in their best moments, on epic songs such as Here to Stay or Thoughtless, Korn blend this rhythmic aggression with the weaving, modal approach to melodies of, say, Faith No More, and achieve a grandiose, pseudo-operatic wall of tuneful noise. "Do Korn still know how to fuckin' rawk?" shouts Davis. They do.

The audience, featuring a disconcerting number of 12-year-old children, loves it. In between songs, a guitarist launches into the riff from Led Zeppelin's Whole Lotta Love. "Fuck off!" shout the audience. But then they probably know it only as the Top of the Pops theme tune.