Crooked Still takes bluegrass, then uses its imagination

Crooked Still never made a conscious decision to play Bill Monroe's bluegrass standard "Can't You Hear Me Callin' " in a funk rhythm. The subtle echoes of Nirvana on "Ain't No Grave" are not the result of a master plan. Neither, for that matter, did it occur to the young quartet that banjo, cello, bass, and voice is a mighty counterintuitive, if not totally illogical, instrumental lineup for any style of music.

"The sound was more of a discovery than an invention," says the band's banjo player, Greg Liszt, who divides his time between Crooked Still and Bruce Springsteen's Seeger Sessions Band. "We initially got together because the four of us just happened to like to tackle these traditional songs with a similar aesthetic. We just started jamming."

The members of Crooked Still were students when they gathered in dorm s and cafeterias in 2001 for those early sessions: Singer Aoife O' Donovan and bassist Corey DiMario met at the New England Conservatory, cellist Rushad Eggleston was studying at Berklee, and Liszt was working toward his doctorate in biology at MIT. Five years later, with the release of the group's second album, "Shaken by a Low Sound," Crooked Still is one of the brightest lights in the neo-bluegrass movement -- and but for a few guest turns, nary a guitar, fiddle, or mandolin in sight. They play at the Somerville Theatre tonight.

The tunes on "Shaken by a Low Sound" are traditional and public domain songs -- entirely reimagined. It's not an extreme sound; these aren't heavy- metal interpretations of Robert Johnson or punked-up field recordings. Crooked Still's transformational powers are quietly radical. There are no percussion instruments; "Little Sadie," a folk ballad dating to the 1920s, is propelled by Eggleston's snarling cello. Dylan's "Oxford Town" segues into the Appalachian ballad "Cumberland Gap" in a blur of four-fingered banjo riffs. Most banjo players use three picking fingers; Liszt, in the spirit of scientific inquiry, spent years seeing if he could get his ring finger working. O'Donovan's water-clear soprano skims and glides in angelic counterpoint to DiMario's deep-blue bottom end.

It's those contrasts, says O'Donovan, that give Crooked Still its unique identity.

"Last summer Rushad was only listening to Metallica and AC/DC. Greg listens to a ton of hip-hop, and that comes through in his rhythmic banjo parts. I listened to a lot of Joni Mitchell and Paul Simon growing up," says the singer. "But there's no creative tension. It's like adding more to the pot."

To capture the raucous sound of their live shows in the studio, the band turned to producer Lee Townsend, an unlikely choice for a progressive roots music project. Known for his work with jazz musicians such as Bill Frisell and Charlie Hunter, Townsend came to the table with no preconceived notions about what a bluegrass band can and can't do.

"Having someone outside the genre had its challenges," says O'Donovan, a Newton native whose father, Brian O'Donovan, is the host of the WGBH Irish music program "A Celtic Sojourn." "But it worked well. Lee had no expectations of what it should sound like, and he really encouraged us to lay back, to get into a groove."

The band recorded "Shaken by a Low Sound" in rural Northern California. They were still on the West Coast mixing it when Liszt got a call from Larry Eagle, a drummer he'd played with in the Wayfaring Strangers, asking if he was interested in auditioning for a spot (as it turned out, the one center stage, right next to the Boss) in Springsteen's new band.

"It's a 28-year-old banjo player's fantasy," says Liszt.

It's also a logistical challenge for Crooked Still, which has hired Noam Pikelny, a 23-year-old banjo virtuoso who's played with Leftover Salmon and Chris Thile, to sub for Liszt. Liszt flew back to Boston for tonight's big hometown show; he'll rejoin Springsteen Monday in Cologne, Germany.

"It's a great opportunity for Greg," says O'Donovan, who concedes that the band's initial reaction was frustration. "But we've been lucky enough to have a great solution to the problem in Noam. He brings a whole new spice."

With the exception of DiMario, who just moved to Brattleboro, Vt., all the Crooked Still members live in Boston. Not that they get much work done here in town. Most of their arranging and rehearsing happens on the road, in hotel rooms, on stages after sound checks, wherever the moment strikes. Liszt will be back with "the family," as O'Donovan describes it, at the end of the month. They're already tossing out ideas for the next Crooked Still project. Like the others, it will involve a process and a product that's beautifully crystallized in the band's moonshine-derived name.

"I don't know if our music messes people up like whiskey does," says Liszt. "But it is definitely distilled."

Joan Anderman can be reached at anderman@globe.com.