The title of Matthew Bower's latest project automatically brings to mind his Sunroof! outfit, whose Panzer Division Lou Reed remains one of the man's best releases. However, where Sunroof! saw Bower twisting banks of feedback noise around grungy guitar arpeggios. As such, Sunroof! connected vividly with the earliest incarnations of his most famous band, Skullflower. Black Sun Roof!, meanwhile, feels like a continuation of more recent Skullflower releases, which perhaps makes sense because, like that in band's most constant recent line-up, and in Voltigeurs, he is partnered by Samantha Davies, here performing mostly on violin, with Bower as ever using his guitar as one mighty noise source, bolstered by some equally freaked-out synths. The pair have been collaborating for several years now, and they've developed in that time a potent form of noisy synergy, regardless of the name they're operating under.

4 Black Suns & A Sinister Rainbow is, unsurprisingly, a loud and fucked up beast of an album, but Bower and Davies' approach to these 12 tracks - spread out over two CDs - in a very different fashion to their previous work as a duo, mainly through their use of unruly, faltering rhythm patterns as an ever-shifting bedrock for most of the tracks. Skullflower started life as a full-on noise rock band, complete with muscular drums, but here the forward momentum, such as it is, is provided by a sickly-sounding drum machine that the pair use to inject added unease rather than actual rhythm, as snare loops bubble up and recede in disconcerting fashion, evoking the brittle pulsations of early 80s industrial electronic music, notably San Francisco goth-nihilists Factrix. As such, whilst 4 Black Suns & A Sinister Rainbow flows from the same dark, sense-sapping well as Skullflower and Voltigeurs and Sunoof!, it operates on a subtly different level.

If you consider the titles of recent Skullflower albums such as Strange Keys to Untune God's Firmament, Malediction or Fucked on a Pile of Corpses, it's easy to discern a form of bleak spirituality, a pursuit of gnostic philosophy rendered abstract as Bower and his various musical partners pile on the waves of distortion. His erstwhile band and label mate Gary Mundy has spoken to me in the past of "bleak psychedelia", and Bower seems to generally aim for the core of those two words, to the point that they become irrevocably intermingled. As the high-octane drones of 4 Black Suns & A Sinister Rainbow wrap themselves around ones senses, however, it soon becomes clear that Black Sun Roof! is both more and less abstract than anything Bower has done before, as if the haze of distortion is keeping something concrete and tangible just out of arm's reach. On the first disc, 'Truffled Abyss', the level are cranked into the read, but fluttering synth phrases and beats seep through the cracks between the walls of noise, outlining half-formed melodies usually framed by Davies' overdriven, yo-yoing violin lines. Via e-mail, Bower speaks of the pair's desire to move away from existing 'dark' music archetypes, with Black Sun Roof! instead trying to create their own "alien artifacts". In a way, it reminds me of artists like Wim Mertens or Sigur Ros inventing their own languages: the strange collages of synth, rhythm, violin and guitar; of melody and dissonance feel familiar ("concrete", as Bower puts it), but never to the point of being instantly recognisable. Black Sun Roof! exists very much in a world of its own, one that they allow to bleed into ours, and into their own history.

'Perfumed Pressure', the two-part opening salvo, blasts the album into existence with Bower's trademark squealing feedback heralding familiar multi-layered guitar mayhem, which sounds like he's been spending time in an underground wind tunnel buffeting his ears with white noise. However, the aforementioned beats, which skip and collapse like the minimal rhythm on Factrix's 'Center of the Doll' underpin the track, keeping it from soaring into the spheres, whilst ghostly half-formed sounds evoke sinister voices sounding from behind a wall of fog. We're a long way from Umberto's more overt sci-fi explorations on his latest album, Confrontations. The aliens on 4 Black Suns & A Sinister Rainbow are only suggested, like something moving at the corner of perception. Later tracks such as 'Monstrous Souls' and 'Glassy Penetralia' will feel more familiar to Skullflower fans, except even these are suffused with gasping rhythmic pulsations and sketches of synth or violin harmonics, but these wisps of light amidst the darkness are used as texture and colourations rather than as mere counterpoints the unforgiving monstrous drone Bower rips out of his six-string.

The second disc, 'Werewolf Universe' is markedly different to the first, a more subdued affair where Bower and Davies' ever-shifting patterns evolve less monomaniacally. Here the various components, be they distant voices, juddering drum machine explosions or entwined violin/guitar duels, dance and phase around and in and out of each other. Even on the 10-minute epic 'Thunderbolt Cumshot Axis' (what a title!), the interplay is dextrous, even subtle, the music seeming to build up of its own accord, as if Davies and Bower are mere channels for something bigger. Bower compares it to a "virus", and it's true that 4 Black Suns & A Sinister Rainbow may be his most organic and unpredictable release for a very long time. And fear not, Skullflower and Voltigeurs fans, these tracks are so loud and monolithic that you can still get lost in them as the waves of sound roll over you, like the best of both those bands.

4 Black Suns & A Sinister Rainbow is a long and occasionally impenetrable album, one which seems to be in perpetual motion, the various instruments colliding until they're barely distinguishable, and yet with splinters of texture and atmosphere colouring each carefully-crafted piece. It won't be too everyone's taste, and it's incredibly, overwhelmingly long, but it's another thrilling direction that Bower and Davies are taking. Oh and, despite what you may have read, there actually isn't a hint of tremolo on any of the tracks.