North Carolina folk-rock group maintains its humility, even while hanging with Dylan and Rick Rubin.

Seth Avett says he doesn't know a lot about love, but he's learning fast. "Every time I think I know a lot about it, I'm brought back to Earth," he says. "Love is a very humbling thing."

Fittingly, North Carolina's Avett Brothers are humble gentlemen. Avett, his older brother Scott and bandmate Bob Crawford made their name on an immediately likable mix of heartfelt, folk-rock love songs and singalong country, along with a reputation as some of the most modest, aw-shucks guys to grace a stage. (Joe Kwon and Jacob Edwards back up the trio on the road and in the studio.)

Still, it's hard to be humble when your band is skyrocketing. In 2009, the group released the Rick Rubin-produced "I and Love and You", its sixth since 2002. The record cracked the top 20 of the Billboard 200, has sold 429,000 copies (according to Nielsen SoundScan) and pushed the band head-first into the folk explosion led by Mumford & Sons, Old Crow Medicine Show and Justin Townes Earle. At the 2011 Grammy Awards, the Avetts joined Mumford & Sons as Bob Dylan's backing band. Now, three years after its last album comes "The Carpenter", out Sept. 11 on Rubin's American Recordings, with the producer again at the helm.

Seth Avett sees the band's early years, spent carving out a fiercely devoted fan base, as chapter one, with 2007's ragged "Emotionalism" as "the period of us doing everything on our own." "I and Love and You", then, was the beginning of chapter two: a fresh start, but not without its problems.

"We were processing tons of new elements," Avett says. "Working with Rick for the first time, recording outside North Carolina for the first time. It's an intimidating scenario to make a record with Rick. The record's faults are just us acclimating to a new era, but with 'The Carpenter', we have our sea legs."

Recorded in North Carolina -- with Rubin's involvement mostly coming through emails and phone calls -- "The Carpenter"'s 12 tracks are polished, sincere Americana. The rough edges of early releases are gone, much as they were with "I and Love and You", but the band's lyrical obsession with love, manhood and relationships remains.

The most jolting change is the album's visibility. While Avett still believes that "word-of-mouth is where it's at," the new songs will be heard in Starbucks, which is distributing the album, and in Gap commercials, as part of the chain's "Be Bright" campaign.

"Some people will look at what we do promotionally and say, 'Sellout! They're in it for the wrong reasons,'" Avett says. "But we've got to follow what feels right in our hearts. [The Gap ads all feature] brilliant artists just under the radar. Gap is a good place for the common man to get some handsome clothing."

Therein lies the Avetts' line in the sand: their accessibility balanced equally with quality-an obvious parallel to the band's music, which is all-American, well-worn and dependable.

"[Gap and Starbucks] are very available, and we feel good about that," Avett says. "Doing an ad for a $20,000 watch, you're excluding people."

Exclusion is the furthest thing from Universal Republic senior VP of marketing Jim Roppo's mind. He's working in partnership with American Recordings and says the time is perfect for a major breakthrough. "Their style of music is in the limelight all around the country over the last few years," Roppo says. "As other acts grow the market, the Avetts grow as well. We've seen it with Mumford -- there isn't a limit."

Avett's goals are a bit more modest. "My rock'n'roll fantasy is to have the credentials to go anywhere at a festival," he says. "We've played main stages where I can't even get backstage. I don't want to be there to drink beers with famous people. I just want to use the bigger [portable] johns."