3-1/2 stars (out of four)

If that were the single, overriding message of this film, you could lump it into a pile with 1,000 other music movies and call it a day. Yet what sets "loudQUIETloud" apart, as with many outstanding documentaries, is that there's a bit of dumb luck involved; filmmakers Steven Cantor and Matthew Galkin catch distressing and poignant moments on the tour that, if written into a fiction film, would seem too scripted to be true.

Alas, "loud" shows drummer David Lovering--who turns to magic as a post-Pixies hobby-career--disintegrate into Valium-fueled madness with the death of his father from cancer. The scene where band members confront Lovering in the van must rank among the most dysfunctional, uncomfortable interventions ever caught on film. The only thing more pathetic than lead singer Black Francis' half-hearted entreaty is Lovering ignoring him with a spaced out leer, ear buds jammed into his bald noggin.

Bassist Kim Deal, meanwhile, takes to the road with her identical twin sister Kelley in tow as a security blanket and sounding board. Fresh from a lengthy drug rehab stint, Kim sports an ever-present groggy look one might mistake for caffeine deprivation; she travels in a separate vehicle from the other Pixies, writing songs for a comeback album with the Breeders, the band she formed with Kelley after the Pixies' acrimonious split in 1993.

If ever a band carries itself off on film as the anti-Beatles, the Pixies would be it. Much of "loudQUIETloud" is filled with awkward, silent interludes where the four members barely speak to each other, or else sport all the social skills of geeked-out college freshmen. About the only concrete show of solidarity is when Francis, Lovering and guitarist Joey Santiago all shave their domes down to the bare skin--this just as the Boston band begins to gel onstage after 11 years in dormancy.

Tantalizing questions hang in the air like reverb-drenched feedback; Francis bemoans the fact that some songs he's working on could be demos for a Pixies comeback, if only his bandmates would express an interest. They never do, and to this day a new Pixies studio album remains an uncertainty. But hearing the group romp through chestnuts such as "Caribou," "Where Is My Mind?" and "Something Against You," we clearly grasp the mix of pop lightning and punk thunder, sugary lust and sour angst, that made the Pixies such a force. Viewed in that light the band's legacy, if not one of fame, was one of influence. As Nirvana's Kurt Cobain acknowledges in the opening quote, without the Pixies there would be no "Smells Like Teen Spirit."

lcarlozo@tribune.com