Music: Lean, mean and completely unpredictable

Moby

Scala, London

Arab Strap, Dot Allison

Union Chapel, London

You never know what to expect at a concert. One evening he might concentrate on expansive, epic techno, with ethereal piano and billowing sheets of strings. Another night you might hear "Anarchy in the UK" played on an acoustic guitar or a savage thrash-funk mauling of the James Bond theme with a Public Enemy rap in the middle.

On Wednesday, and his band played all of these, and the impossibility of knowing which guise he would adopt next made for a genuinely exciting gig. His tendency to head-butt his synthesiser helped too. He finished the show standing topless on a keyboard, his arms over his head, in a crossfire of strobes and a cloud of smoke, while the speakers pumped out "Thousand", a frightening racket which is listed in the Guinness Book of Records as the fastest single ever. Clearly, Top of the Pops beckons.

The journalistic cliches about are as follows. He is a shaven-headed, Christian, vegan environmentalist who covers his record sleeves in persuasively pragmatic editorials beginning "Fundamentalism of any kind troubles me" or "It horrifies me that we allow prisoners to be treated so poorly". (1995's Everything is Wrong was responsible for my own vegetarianism. Sad, eh?) His real name is Richard Hall, but he calls himself because, he says, Herman Melville was a distant relative.

Certainly trying to place him in the pop world is a bit like hunting a white whale. is a New Yorker, but the artistes one is tempted to compare him with - Underworld, Prodigy, Faithless - are British. The only transatlantic comparison that comes to mind is David Byrne, with whom shares an edgily deadpan and formal way of delivering his modest quips between songs.

Wednesday's show spanned his whole output, from 1991's proto-rave anthem, "Go", to material from this year's tremendous album, Play, whose defining tracks are early field recordings of blues singers given the treatment. It was as entertaining as it was noisy. Whether his next show will be anything like it is another matter.

Arab Strap are unlikely ever to be mistaken for and co, largely because if Aidan Moffatt stood on his keyboard it would snap. Instead, he sits behind it, letting the lyrics dribble down his beard along with the wine he swigs from a bottle. As for the other three members of the band, 's cohorts are muscled, peroxided and barely dressed. Moffat's sidekicks keep their cardigans zipped up. And if can boast the fastest song ever recorded, Arab Strap's songs are as slow and repetitive as Chinese water torture.

Having said all that, Arab Strap are one of the country's most important bands. While so many of their peers seem unsure of quite why they're in the business, Arab Strap are commited to chronicling a world that no one else does. And that world is Falkirk. In bleakly witty couplets, Moffat tell us of his relationships in all the red raw, autobiographical detail you don't hear in Chris De Burgh's songs: the infidelities and the paranoia, the grubby sheets and the fag ends, the itchings and the hangovers. There are few Arab Strap songs that don't have the word "pissed" in them somewhere.

What with the echoey acoustics, Moffat's bleary groaning and the band's absent-minded failure to hand out transcripts before the concert, most of of the lyrics were indecipherable on Thursday. But the songs managed to retain some of their emotional intensity, thanks to the guitar heroics of Malcolm Middleton - Johnny Marr to Moffat's Morrissey. He is as devoted to Arab Strap's vision as Moffat is, and together their conviction can almost make you imagine that they look cool as they perform. That's saying something.

Arab Strap's support act, Dot Allison, sang songs from Afterglow, a sumptuous, narcotic-spiked banquet of candy-floss pop, French-flavoured ballads and Indian-spiced, psychedelic mantras. Once again, though, the material wasn't really done justice by the clattering sound quality or Allison's waifish awkwardness: when she wasn't brushing blonde hair off her face, she was brushing it back on again.

Maybe she's just nervous. She had a shot at stardom in the early Nineties as the singer of the much touted Scottish dub-rockers, One Dove. They turned out to be a lame duck: after one Andrew Weatherall-produced album, a conspiracy of band politics and record company politics pulled the group apart in 1996. Soon afterwards, a car accident put Allison in a wheelchair for four months.

It must be time for her to receive her share of good luck. In October she releases her debut solo album - although "solo album" is barely appropriate given the stellar crowd that surrounds Allison's cooling breeze of a voice. Among the names on the credits are Richard Fearless of Death In Vegas, Kevin Shields of My Bloody Valentine, Mani of Primal Scream and Ged Lynch of Black Grape. BJ Cole, the veteran pedal steel guitarist last seen filling in for Nick McCabe in The Verve, adds some fragile notes to "Tomorrow Never Comes" and Burt Bacharach's lyricist, Hal David, co-wrote "Did I Imagine You?"

It's a lush, dreamy record, and even played live, without the celebrity line-up, the quality of the songwriting shines. After Allison's set, people were mentioning Bjork and Portishead, the Cocteau Twins and the Chemical Brothers. People were also mentioning Everything But The Girl and Enya, but don't be put off.

: Glasgow Garage (0141 332 1120) 23 Oct; Manchester Hop & Grape (0161 275 2959) 24 Oct; Scala, N1 (0171 833 2022) 25 Oct. Arab Strap: Leeds Joseph's Well (0113 203 1861) Mon; Edinburgh Liquid Rooms (0131 225 2564) Tues; Glasgow Mitchell Theatre (0141 287 4855) Wed