One of the subtleties that gets left out of the still ongoing CD vs LP debate is the mood swing that could occur in the transition from side one to two of the vinyl disc. Think of the shift from icy r'n'b to synthetic symphony David Bowie and Brian Eno concocted on Heroes and Low. Two of Charles Mingus' finest and most underrated works, "Cumbia and Jazz Fusion" and "Music for 'Todo Modo,'" have so little to do with each other that they would barely make sense together were the listener not required to get up and turn the album over. And would Rush's 2112 have felt so epic if it was just a long track rather than a full side?

The Necks, the Australian superstars of new music improv, have lived a career on the shiny surface of the CD. The slowly evolving, hour-long excursions they craft in concert simply won't fit on an LP side, and one of the clear pluses of the compact disc is its uninterrupted length. But even still there's something exhilarating about their new Mindset. It's not their first release with more than one track, but in 23 years it's their first LP release and the first to follow the configuration of two 20ish-minute cuts, allowing for a remarkable mood swing when the vinyl is flipped � although not so schizophrenic (unlike the Mingus reissue) as to undermine flow on a CD.

The first half, "Rum Jungle," is probably the most maximalist thing the band has recorded, thanks perhaps to electronic effects likely supplied by drummer Tony Buck (the album lacks performer credits, but Buck has been adding processing to their live shows), although some crackerjack engineering plays into it as well. Sound fills every crevice in the music. They're still an acoustic trio, but the piano, bass and drums here are all enormous. And rather than a slow ramp up, the track begins at full immersion and doesn't let up. It's absolutely thrilling.

The second part of the program is more subdued but no less intoxicating, and retains the feeling of uncertain sound origination from the first half. Titled "Daylights," the track has the blurrily attenuated feel of having stayed up all night. Chris Abrahams' keys are nearly a vibraphone and Lloyd Swanton's bass at times sounds like a drum. Buck's drums, meanwhile, are as always so staggeringly consistent that they can disappear, taken for granted like the ticking of a clock. Unlike "Rum Jungle," this piece does exact a slow build, with more and more voices � organ, perhaps, or an errant laptop folding in. It's gorgeous, lulling disorienting.

The Necks isn't quite like any other band (although some fine ones, such as Dawn of Midi are arising in the wake). There's a manner in which they always seem the same, and it's within that that they're always so different. And Mindset is even differenter than usual.