My dubstep, how you've grown. When we first met on a balmy midsummer's night at DMZ some six-odd years ago, it was hard to imagine such a somnolent and surly sapling of a scene ever reaching far beyond its south London birthplace. Now here we are in 2011 and you've grown into a fully-fledged genre, you've goosed the charts via the likes of Magnetic Man and Katy B, and you even managed to get your bass-lovin' fingers into the pie that was Britney Spears' 'Hold It Against Me' single earlier this year.

Of course, Black Sun isn't strictly a dubstep album. No, apparently it's 'bass fiction', a '"micro genre" initiated in 2004' by Kode9 and The Spaceape. Nevertheless, it would be interesting to know the opinion of Steve Goodman (as Kode9's mum knows him) on the mainstream acceptance of the genre he played a key role in developing, not least by signing Burial to his Hyperdub label and releasing his critically clusterfucked debut and second albums in 2006 and 2007 respectively.

Is Kode9 proud to see dubstep move into the limelight? Is he made up to see those who have beavered away behind the scene's, er, scenes get their day in the sun? Is he overwhelmed to hear pop strumpets adopting the sound of the underground? Or is he dry-retching at the thought of yet another untethered and tempestuous form of artistic expression being bastardised and sanitised with the unyielding veneer of crass commercialism, leaving it as threatening and thought-provoking as an animated meerkat hawking insurance products? If Black Sun is anything to go by, then the chances are that Goodman's head is in a different galaxy to the one where dubstep is teamed up with a lyrical beauties like "Cos' you feel like paradise/And I need a vacation tonight".

Teaming up once again with MC The Spaceape, as he did on 2006's Memories Of The Future, Black Sun is touted as exploring 'an accelerated sonic fiction'. In practise this means a dense, claustrophobic and sometimes jarring concoction of bass, synths and assorted sonic shrapnel that looks to push things forward. Opener 'Black Smoke' is as good example of this as anything here – distant tribal drumming and the crackle of fire gives ways to nervous beats, fidgety clicks and the precise drawl of the Spaceape. Suffocating and paranoid, it's something akin to Mezzanine-era Massive Attack being given a dense, intense digital age doing over.

'Am I' sees the duo almost venturing into conventional hip-hop, Kode9 summoning up an aggressive throb strewn with siren samples over which the Spaceape spits forcefully about revolution and liberation. 'Bullet Against The Bone' is of a similar bent – heavy bass beats, abrupt bleeps and bloops, more sirens (of the air raid variety this time) and The Spaceape epitomising it's uncompromising attitude with the line "this is no pacifist time". These, along with the mash up of bassline and life support machine samples that is 'The Cure', see the duo playing to their strengths – a dark, menacing take on dubstep matched with angry, apocalyptic rhyming.

However, elsewhere, particularly in the second half, Black Sun sorely lacks such dynamism and momentum. The twinkling shimmer of 'Promises' ultimately fails to go anywhere and the "yeah"s and "uh"s that pepper the skittering 'Neon Red Sign' are reminiscent of the generic house that soundtracks small town Saturday shopping. Both suffer from the Spaceape's contribution plumbing the depths of Maxi Jazz-alike New Age, stream of consciousness mumbling.

Equally disappointing are Kode9's attempts to broaden his scope with the slower, predominantly instrumental likes of 'Otherman' and 'Green Sun', which are swathed in synths that sound like they were left over from Queen's Flash Gordon soundtrack. The former sounds dated while the latter never really rises above the horizon. The biggest letdown is the closing 'Kryon', Kode9's collaboration with electronic experimentalist Flying Lotus, - three more minutes of ponderous '70s synths decorated with echoey, unintelligible speech and the sound of rain. It's about as progressive as practising phrenology.

The dreamy, astral melancholy of 'Hole In The Sky', sadly the shortest track here, but perhaps all the better for that, shows what 'Kryon' could have been. Together with the Autechre-go-UK-funky Partial Eclipse Version of the title track, it provides a roadmap of where Kode9 and the Spaceape could have gone with this album – moving away from dubstep to an altogether different sound, rather than exhausting their drive and discipline in trying to remould a genre where innovation is currently directed towards how it can survive and thrive in the mainstream. Still, you can't hold it against them...