The name of Jah Wobble's indie label tells you what to expect: 30Hz. What he delivers above all (or rather below all) is low frequencies, the furniture-rattling dub tones you feel in your spine. Wobble has hammered the basslines of classic reggae into a hybrid, reductionist genre of his own making.

Traditional dub can turn a mix upside down, revealing what a rock song would sound like were you lying on the floor with your ear next to the bass speaker. Wobble, in a new inversion, adds thunderous loops, live drums and ultra-deep bass to musics and musicians that rarely venture in that direction.

So Wobble's current tour is something of an avant-rock-world-jazz variety show. At times he is the only person on stage who is not improvising. Smartly turned out in jacket and tie, he sits riffing in a corner while diverse performers come to the fore: impressionistic turntablist Philip Jeck; Molam Lao, a quartet of Laotian musicians; plus Chris Cookson, Harry Beckett, Clive Bell and Jean-Pierre Rasle from Wobble's regular group, Deep Space.

Visuals by photographer Marc Atkins are projected on a screen behind improv drummer Mark Sanders, who locks into Wobble's patterns like an LA sessioneer. The Laotians sing molam, which Bell has called Laos's answer to reggae; it is full of humour and bawdy rhyme. Thongphiane Bouphavanh and Sengphet Souryavongxay are engaging singers, but many of the instrumental nuances get lost in the gig mix. This is also the case with Jeck's complex layering and transformation of battered old vinyl, and Beckett's squiggles: you can't hear the detail.

Still, what you lose in subtlety you gain in, er, bass. Which might be great in a place with good sound, but not, alas, in this venue. Someone on stage mouthed "shoot the engineer" - unfair, because the mixer was doing his best, adding creative dub echoes to Bell's flute, Beckett's muted trumpet and Sanders's kit. In the absence of a decent listening experience, the blase London audience continued to drink, smoke and snog - this was Friday night, after all.

· At Roadmenders, Northampton (01604 604222) tonight, The Boardwalk, Sheffield (0114-276 6356) tomorrow, then touring to Manchester and Kendal.