With its heavy emphasis on a populated UK borough and steady incorporation of Eastern and Asian influences, Margins Music is an artful documentary record, capturing the scattered soundtracks of London’s busy streets in field recordings and diverse musical channels. This mostly instrumental full-length debut, powered by hypnotic melodies and subtle beats, follows a handful of well-received dubstep singles from producers Dan “Dusk” Frampton and Martin “Blackdown” Clark.

Martin Clark has for years demonstrated an interest in purveyors of grime and dubstep as an observer, reporting from the growing scene. Keysound Recordings is his label, and he helped compile Tempa’s Roots of Dubstep as well as the essential Run the Road grime collection. Though Clark is surrounded by contemporary dubstep and grime artists, often speaking with them and writing about their work, his output as Blackdown is rooted in original concepts and sonics. He and Dusk share some obvious traits with Pinch, in lush, thickening dubs, or with Cyrus, in the frequent use of Eastern flourishes that the Random Trio member and Shackleton favor, but Margins Music is distinctly their own. It’s a rich exhibit of alleyway atmospherics, loops of ancient-sounding instruments, and shifting musical landscapes.

The pack of roads navigated on Margins Music, in an effort to illustrate all the cultures that meet in the UK’s most expansive urban area, are surprisingly less like an array of singles and more like a slick, cohesive album. It’s not as spooky as Flying Lotus’s Los Angeles, and it’s short on the muscled-up drive that Kevin “The Bug” Martin organized for his London Zoo. Margins isn’t a brawny outing; its attention to playback detail and all-inclusiveness, however, renders it just as enchanting as these other records. D + B’s sorcery on “Concrete Streets” pins guest emcee Durrty Goodz against the same kind of busy arrangement that London Zoo‘s cast deals with. A shuffling undertow tumbles beneath “Concrete Streets”, and Durrty enthusiastically brags around it; faux strings and gritty synths plunge in and out while the East London vocalist reminisces and pledges his authority (“Ask anyone, I run these streets,” he spits). Again, this is mostly an instrumental affair, but Dusk + Blackdown’s productions are top-shelf whether a vocalist shows up or not.

Margins Music‘s subject is canvassed by the producer duo and appropriately unveiled by Roll Deep member Target at the onset. The opening “Darker Than East” is layered with warbling synths and background church bells, while its kicks punch in behind loops of rather limited narration from Target. The more structured grime cuts here (voiced by guests Trim and Durrty Goodz) are indisputably London-centric, while brief interludes “(Keysound Rain)” or “(Keysound Radio)” pay tribute in either looped conversations or ambient field recordings. Audio dynamics are as valuable to this collection as the neighborhoods at its partly gloomy center.

“Darker Than East” boasts extreme channel separation that is not a fluke. Rather, it’s one of the record’s many strengths. Margins Music is headphone music through and through, with each tick and casually worming swoosh calculatingly placed at a particular nook in the final mix. “Con/Fusion” features singer Farrah and meditative, speaker-swapping interplay of tablas and rubbery plinks, dressed in sitar and other droning components. Farrah’s contribution is regularly treated with a slow, lingering delay effect, so that the end of her vocal line sometimes slips into the instrumental base of the track, smoothly partnering with the melodies just beneath it. Don’t bother trying to experience this meticulously blended mass of dubstep, garage, grime, and more with anything less than what Don Cheadle’s stereo salesman in Boogie Nights called a “hi fidelity” system. The documentary to which Dusk + Blackdown are clearly devoted doesn’t end at genre-hopping, and enriched playback during this compelling audio examination of London is an evidently weighty priority.

• "Multiple songs" MySpace