Slow Club, Cabaret Voltaire, Edinburgh

Once upon a time there was a boy/girl band who hailed from Sheffield. They made a debut album called Yeah So which married whimsical indie-folk and a kind of post-punk rockabilly to words seemingly torn from the diaries of a pair of teenage sweethearts, holding hands in the rain one minute, crying into their snakebite the next, all the time hoping that this might last forever rather than just until the end of Fresher’s Week.

If this was the opening act in the tale of Slow Club, the duo formed in 2006 by Rebecca Taylor and Charles Watson, their second album Paradise, released last week, has moved the story forward. It's an altogether more meaty proposition which largely ditches the lo-fi, home-baked, close harmonising of Yeah So in favour of something bigger, louder and a little duskier, not to mention more complex and, well, grown up. As part of this evolution Taylor has effectively graduated from co- to lead vocalist, relegating Watson’s pleasant but indistinct voice to supporting status.

This all makes compellingly good sense on record. On stage, however, it was all a bit of a mess. With the addition to the ranks of a drummer and bassist to help deliver the new sound to the live arena, two have become four; it often felt like a pair of outboard motors had been strapped to an old bone shaker, to the benefit of neither.

As a live band Slow Club haven’t quite made the two- or three-rung leap up the evolutionary ladder needed to bring Paradise to fruition on stage. Where on record last night's opener “Where I’m Waking” betrays a thrilling (though perhaps a mite too obvious) similarity to their Moshi Moshi label mates Tilly and the Wall – the banks of stacked female vocals; the clacking, primitive rhythm; the compelling push-and-pull between euphoria and mania – in the flesh it sounded more like a muddy, murky pub band aping Wild Beasts.

Amid the uneasy fusion of disparate sonic elements, it was the quieter, simpler moments that lingered

It rather set the tone for a disappointing night. Taylor has all the hallmarks of a fine front woman - confident, striking, always watchable - but somehow she didn’t quite convince. Back when Slow Club were a duo she would bash out percussive tattoos on everything from chairs to water-filled wine bottles. Now that they actually have a drummer, her continuing rhythmic augmentations felt more like an affectation than an attempt to add anything tangible to the music. And without wishing to appear unkind, she might have been better advised to have concentrated on her vocals. On several songs she was what Simon Cowell would have called “pitchy” - and for once music’s Mr Nasty would have been right. No amount of reverb (and by God, there was a lot of reverb) or the liability of a poor sound mix could completely disguise or excuse several wayward notes.

There were other problems. Watson’s spotlight turn on “Horses Jumping” fell to bits half way through, by which point you could sense some of the sold-out crowd (which included King Creosote in a comfy cardie) starting to lose the thread, as the initial heady expectation turned to something closer to disappointment.

Amid the uneasy fusion of disparate sonic elements, it was the quieter, simpler songs which lingered. The banjo-led “Come on Youth”, from their debut, was lovely, while the utterly convincing "Never Look Back”, a song which dared to stare loss hard in the face, was dark and bluesy, like The Beatles' “Don’t Let Me Down” suffused with the rootsy, off-kilter oddness of Bob Dylan & The Band‘s The Basement Tapes.

These moments, alas, only served to make much of the rest appear messy and half-cocked. Perhaps it was just an off night. I hope so, because the album is well worth a listen. But on this evidence, by the end I couldn't help thinking that - whisper it - maybe Slow Club are better off being a winsome indie-folk duo after all?