Saturday: They're not Mumford & Sons or the Dave Matthews Band, but the Avett Brothers fall somewhere in between musically, and are a big enough fixture on the outdoor summer concert circuit for Somerset Amphitheater to build a mini-fest after them. North Carolina's rootsy balladeers and bluegrassy rockers are playing summer gigs leading up to a fall release of the follow-up to last year's Grammy-nominated album "The Carpenter," this one also produced by Rick Rubin. They're meeting up in Wisconsin farm country with celebrated Seattle singer/songwriter Brandi Carlile, whose rabid Twin Cities fan base rivals the Avetts', plus fun-bopping Philly hippie rockers Dr. Dog, whose "Be the Void" was the catchiest rock album of 2012. Avetts-like Texas pickers the Wheeler Brothers open. (4:30 p.m. Sat., Somerset Amphitheater, 715 Spring St., Somerset, Wis., $47-$87, kids $35, Ticketfly.com; campsites at SomersetAmphitheater.com).