DJ-mix albums are uninterrupted flows of various tracks that re-create dance jocks' sets. These albums allow people to hear hip-hop and dance tracks the way that clubgoers – or in the case of Funkmaster Flex, listeners of Manhattan's Hot Ninety-seven radio station – use them. These supermixes create a cool illusion of spontaneity, of choice bits of jams slapped on at just the right millisecond. And in the hands of folks like Flex and London's Chemical Brothers, those series of moments can produce dance nirvana.

Flex doesn't just remix tracks; he remixes years. That's why the cavalcade of rap and R&B stars on The Final Chapter can't stop giving him mad props. "I ain't goin' for that 'I heard Volume One, I heard Volume Two' stuff," veteran rapper Busy Bee warns, referring to the best-selling mix albums that Flex coordinated in 1995 and 1997. The Final Chapter redefines the word jampacked, linking underground phenoms such as Tha Alkaholiks and Xzibit to the more pop-y Mariah Carey, Missy Elliott and Erykah Badu; tapping current comers like Canibus alongside Ice Cube, Busta Rhymes and Eightball; and relying on wild ingenuity from the Wu Tang brain trust. "Every time I feel the need/I envision you on the ones and twos in the DJ booth," testifies Carey. It's just, as more than one rapper advertises, "Volume Three, ba-by." Together, all these moves and tunes mount a vibrant vision of an entire world scaled down and blown up in two-minute shots, worked out with New York verve.

The Chemicals, on the other hand, use the mix-tape format to usher their music in a new direction that's less constricted by the four-on-the-floor big-beat genre they helped invent. On the fantastic Brothers Gonna Work It Out, they cede their cartoon-beat franchise to recent popularizers like Propellerheads. Instead, they offer a wicked tapestry of fresh sounds, boomeranging grooves and aggressive fuzz. Like Beastie Boys, the Chemicals have top-shelf retro-futurist taste, knowing when to bring on records by Seventies obscurities like the Jimmy Castor Bunch or Willie Hutch, from whose old Motown track the album gets its name. The Chemicals' music descends like a filmy rain of a zillion fine, tiny pieces of combined and recombined beats, phrases ("It's time to get down"; "Don't stop the rock") and repeating riffs. Their conservationist streak extends beyond out-of-print vinyl: They revel in Dubtribe's demand "I want my planet back," on "Mother Earth." Like Flex, who'll throw on the occasional old-school nugget, the Chemicals sometimes get sentimental, remixing traditional Brit rockers like Manic Street Preachers. But with an album like this, the Chemical Brothers are showing that they know the big secret about "the future": It's occurring right now. (RS 794)

JAMES HUNTER