SAN FRANCISCO -- Wilco singer/guitarist Jeff Tweedy knows the band's new album, Summer Teeth, falls outside the boundaries of the country-toned rock music that made the quartet's reputation.

The album, set for March 9 release, has an uncharacteristically dark pop sound for Wilco. And that's just fine by Tweedy.

"I have a great interest in folk music and country music, but I did move away from it, and as a band, we probably never felt comfortable being identified as that," Tweedy, 31, said, during a recent interview at the Phoenix Hotel.

Dressed in blue cords, a red flannel shirt, brown boots and a jacket, Tweedy -- who is also a member of the pop-rock ensemble, Golden Smog -- reflected on the new Wilco recording and how it came about.

"This record is more believing in ourselves," he said. "This is where we've moved. This is our new home."

Furnishing the new home are pianos, Wurlitzer organs and an orchestra-simulating, tape-driven instrument known as a Mellotron. The band's increased use of keyboards has rounded out the sound of such new tunes as "Shot in the Arm," as well as the lullaby, "My Darling," and "We're Just Friends," the first song Tweedy has written on piano.

As the Chicago-bred band was trying to nail down the right sound for the new tunes, they relied on what Tweedy described as "kitchen-sink mixes." To help decide what would make the cut, they recorded with every possible idea on tape and then listened back to see what should stick.

Tweedy said that several of the songs, such as "ELT," "Summer Teeth," "I'm Always In Love" and "Via Chicago," were recorded multiple times.

"For us it was really exciting," Tweedy recalled. "It kind of made us go back and re-focus our efforts. [We wanted] to hear stuff that we hadn't necessarily heard before in us, in what we do, and at the highest end of our pretentiousness, hopefully hear something we haven't really heard before."

So many of the songs were graced with additional keyboard sounds that "ELT," one track that didn't initially have any of the enhancements, almost didn't make the album. Then, the band stumbled upon pop singer-songwriter Matthew Sweet's Moog synthesizer at Ocean Way Studio in Los Angeles, according to multi-instrumentalist Jay Bennett. So they added a last-minute synthesizer overdub to "ELT" at Ocean Way.

"It's the first time he's going to find out we used [the Moog]," Bennett, 35, said. "That was one of the songs we were a little worried about because we hadn't done some of the weird stuff to it. It was a big-rock-guitar song, and at the last minute, we were like, 'We have to find some sound that would tie this song to the rest of the record.' "

Wilco formed on the heels of the breakup of the alternative-country band Uncle Tupelo. Tweedy and the Uncle Tupelo rhythm section of drummer Ken Coomer and bassist John Stiratt formed Wilco and released their 1995 debut, A.M. Meanwhile, Jay Farrar, Uncle Tupelo's other principal songwriter, spearheaded the similarly styled group, Son Volt.

With the sprawling 1996 double-disc Being There, Wilco stepped away from the No Depression-style tunes they were known for. With such songs as "Misunderstood" (RealAudio excerpt) and "Sunken Treasure" (RealAudio excerpt), they hinted at the moodier pop territory explored in depth on Summer Teeth.

A darker lyrical bent -- heard in songs such as "She's a Jar" ("She begs me not to hit her") and "Via Chicago" ("Dreamed about killing you again last night/And it felt all right to me") -- dominates the new record.

Tweedy said that, as he was writing the new songs, he was aware these kind of provocative lyrics might spark some intense analysis. But he decided to go ahead with them anyway.

"I can almost guarantee that a lot of it will be misinterpreted," Tweedy predicted. "People will be offended, but it's something I didn't want to edit out of myself.

"I sing, 'She's a jar/She begs me not to hit her,' [but] I've never hit a woman. I don't have any plans to. I've rarely had the desire to. But I've had the desire, and that's probably why that lyric is there."