Orthrelm didn't write OV—a challenging 45-minute exercise in metallic minimalism—with accolades in mind. But the Washington, D.C.–based duo earned their share of surprise compliments in 2005, from a Plug Awards nomination for "Best Avant Album of the Year" to a heavily pierced teen in Scotland who likened OV to György Ligeti's harpsichord pieces. Still, guitarist Mick Barr and drummer Josh Blair remained unprepared for the drive-by homage they received in Athens, Georgia, two weeks ago.

"We pulled up to park, and a car passed with our record blasting out of the windows," Blair says, punctuating the memory with a wonderstruck chuckle. "It's something that has never happened before, and that I don't expect to happen again."

Combining the cruising-tape potential of Terry Riley's In C and Napalm Death's Scum, OV opens with a clattering riff and cymbal clashes. Piercing guitar solos and bludgeoning percussion trade alternating blasts, an exchange that conjures images of laser-beam strikes triggering noisy collapses. A string of ringing held notes, like Jimi Hendrix performing an alien anthem, introduces the crescendo-packed final third. While there are no melodies to grasp, patterns start sticking in listeners' minds after a few listens, like anchors tossed from the window of a speeding train scraping a spark-lined path in solid cement before finally taking hold.

On Orthrelm's earlier albums, the group avoided chords and steady backbeats, writing manically metamorphic short songs that lacked any trace of tangible grooves.

"The old stuff involved concentration in terms of remembering what comes next," Blair says. "With OV, we focus on keeping the energy up through repetitive sections and thinking about the whole flow of the song. We've gone from never repeating to repeating to an excessive extent. They're both mentally and physically draining approaches."

Orthrelm unveiled OV during their live sets two years before putting it on record. The song's instrumental call-and-response dynamic reflects the collaborative process that spawned it. Blair's colossal beats formed the song's foundation, and then Barr added his spiraling, discordant complements.

"I came up with simple patterns, things that were almost symmetrical but not exactly," Blair says. "I crawled inside them to see what could come out of them."

The intentionally imprecise nature of OV's rhythms, combined with Barr's slight pitch changes and speed fluctuations, makes this an album rich with clandestine variations. Even Blair discovers different elements during Orthrelm's OV performances.

"I hear new things every night," he says. "The frequencies will sound different, or downbeats will become upbeats. It's so dense but static at the same time. Someone told us they had wondered why we didn't just loop OV on a sampler, but then they realized the subtleties in how we played it made it impossible to re-create electronically. I appreciated that, because that was the point of the piece."

Orthrelm's OV-inclusive concerts temper almost-unbearable relentless-climax intensity with waves of trance-inducing repetition. It's a turbulent journey, for the musicians as well as the spectators.

"I have found myself nodding my head from time to time, but adding as little movement as possible makes it easier to get through the set," Barr says. "It's wasted energy, trying to make it look like something other than what it sounds like. And to people who aren't accustomed to metal or mathy things, it probably sounds like garbage."

With its dauntingly labyrinthine polyrhythms and shredding solos, Orthrelm play with the sort of technical fervor that makes other musicians either double their practice time or permanently stash their instruments in the closet. However, Blair admits to feeling intimidated by infinitely less complex acts, because Orthrelm's compositional context is so singular that "none of our rules apply to other genres."

"People compare what I do to metal drumming, but those guys are monsters," he says. "I'm afraid to be grouped with them. Some friends in D.C. asked me to play in their straight-ahead rock band, and that scared me. I'd be completely confused."