Living, as I do, in a commuter belt limbo boasting a citizenship of peculiarly large forehead size, it's not every day I get the chance to drop a name. But as I puzzled over Carrier, a chance Google search revealed to me that I used to hang out with this guy once upon a time. The Jack Stevens I knew was a reticent metalhead playing dextrous sheet-glass guitar for local Darkthrone-a-likes Niroth. Metal fans are an obstinate bunch by reputation – perhaps the most tribal of cliques. Those who dare dabble in other arenas are often treated by their peers with marked suspicion. Being true to True Metal requires a complicated hopscotch: step on the wrong square and you risk sullying (pun intended) your metal name. That said, there's almost always an exception to prove the rule. I've known many a hardcore metaller harbouring a secret love for the likes of ABBA, the Commodores, ELO - even cheesed-out happy hardcore and Euro-trance. This very website is testament to the diverse tastes of even the most dedicated metal fans. Still, I couldn't help feeling perplexed, upon our last encounter, to find Jack Stevens shorn of head and affecting a rude Jafaican drawl – the kind of behaviour that'd get you turfed out the True Metal Fan Club faster than you can growl "'The Splendour Of A Thousand Swords Gleaming Beneath The Blazon Of A Hyperborean Empire (Part III)'".

So yes, Jack sacked off to Norwich with his haircut and his accent, never to be heard from again - or so I thought. In the intervening years this weird slow bass music called dubstep started gaining currency among a certain breed of UK clubber. And I laughed and said it would never catch on in any commercial sense. Then, quite typically, I had to go and eat a hat. Everyone from pop princesses to blue-eyed poshboys started adopting dubstep as their own. Even the metal fans were jumping on the bandwagon. In fact they lapped it up as acts like Flux Pavilion and Borgore re-synthesised nu-metal and emo through splat-happy chainsaw wob. Like electro before, dubstep had transcended its status as a mere genre, transmogrifying as it pleased until it had wormed through every nook and cranny of the new musical spectrum. Bass-hungry listeners seeking respite from dubstep's increasing ubiquity began searching round for alternatives. Soon labels like Night Slugs and Hessle Audio were fusing it with house, funky, grime, juke, rave and crunk to create a universal bass sound uncomfortably labelled 'post-dubstep'.

One day an album by a shadowy 2-step producer lands on my doormat. I couldn't have guessed at Sully's identity from the music alone. Carrier bears no resemblance to the schlocky brostep grind that seems to have enchanted so many rock and metal fans of late. Neither is it the kind of thing you'd expect from someone who grew up on the white-hot squall of black metal bands like Emperor and Mayhem. This swinging, shuffling bass music reconciles the various microgenres of future garage, dubstep, UK funky and Chicago footwork under one consistent sound. It's as though in becoming Sully, Jack Stevens has upped-roots and walked to the opposite end of the musical map. And yet for all this about-facedness, there's something in Carrier that retains what I've come to recognise as the proclaimed Spirit of Metal – the core values that make metal what it is, even when experimenters like Ulver break off into many other styles without losing credibility.

For one, there's a stringent adherence to the concepts of 'True' and 'False'. In the same way bands like Immortal and Darkthrone aligned themselves with True Black Metal (a puritanical, no-nonsense movement rejecting the gimmicky tropes employed by the mainstream), Sully is at pains to create an untainted, pure essence form of bass music. Yes, his is an amalgamation of styles, but it's always applied to a strict framework constituting what is and is not 'acceptable'. While recent genre-hopping albums by Toddla T and Chrissy Murderbot aim their shots squarely at the overclocked party market, Sully eschews outré eclecticism, wobbly saw waves and dancehall shoutouts in favour of a consistently flat-plan style reminiscent of Burial sans the reverb-drenched veneer. This is conspicuous, considering even future garage co-conspirators like Erra and Littlefoot have been known to rely on the odd rattling mid-frequency to get things jumping. Sully treats such folly with extreme scepticism. His productions share the starkness of an early Ulver album (minus the crashing guitars of course), allowing each sound to live and breathe in its own space without the layered excess of distortion or pop EQ muddying up the mix. There's a raw, untooled-over quality to the beats that draws parallels with the atavistic production values on BM classics like 'Nattens Madrigal' or 'Battles In The North'. There's also a certain reverence and honesty in the way opener 'It's Your Love' lays Sully's tools out on the table, revealing every beat and throb as a cog in a finely-tuned machine. The stripped-down one-two pulse suggests a pumping heart borne by a grinning homunculus - a beat as bare and complex as the skeletal system.

And there is heart in this most Gothic of garages. Heart, passion, even a foreboding romance in the way the cut-up vocals echo in and out of the mix like fragments of a lovelorn message trying to make itself known from a twirling void. '2 Hearts', kicking in right on cue, steps the emotions up a notch. Ghostly bleeps loom in and out while a lumbering bassline stalks the shadows. This dungeon of heartbreak is lit up by a fluttering micro-synth that recalls 'Aidy's Girl Is A Computer', Darkstar's own forlorn take on gothy 2-step.

These dark emotions don't mean Carrier doesn't bounce. Far from it; much has been made of the ruthless amount of swing applied to these productions. 'In Some Pattern' bumps and grinds in an almost brutal fashion, pesky little stabs blaring away like car horns with a huge smack-in-the-chops slide'n'step clap beat. Sully employs extremism through righteous dancefloor beatcraft as opposed to revving up the distortion as would nu-dubstep posers like Skrillex and Nero.

An album of two halves, the second part of Carrier departs into the currently voguish style of footwork. Along with artists like Machinedrum, Ramadanman, Africa Hitech and Addison Groove, Sully is one of a growing handful of non-Chicagoans dabbling in the genre, and as one would expect he makes it his own. Sully stays true to form, paying the OG footwork DJs due reverence before studiously assimilating their ideas into his own sound palette. The skittering inertia of those original Bangs & Works productions translates perfectly into Carrier's sense of space and stasis. Beats thrash out in all directions, kicking against triggered vocal snatches like someone smashing the shit out of a toy soundmachine. This being Sully, there's a mourning veil draped over every cut. Take away the hyped-up 160bpm rhythms on 'I Know' and we're left with the kind of bleak soundscape redolent of horror movie soundtracks or avant-metal segues. 'Bonafide''s plaintive piano loop is slowly interrupted and broken-up by the rhythmic scuttle, at once paying tribute to the likes of DJs Spinn and Roc and maintaining Sully's funereal ethos.

Those accustomed to the ramped-up compression, swathes of reverb and EQ'd-to-fuck kick drums prevalent in most bass music might find Sully's flat production a barrier. But Sully's unadorned approach to programming allows for much more. There's an openness and an honesty to the music on Carrier that many producers would rather whitewash over with endless special effects and postmodern touchstones. It's by no means a metal album – we can leave that to Skrillex and co. Neither is it the kind of party-in-a-can throw-it-all-in record made by the likes of Toddla T. But it is a proper bass album representing all aspects of the current dance music scene through a noble kind of austerity. Are you ready for Kriegstep?