Charlie Parr's as modest as they come, and his self-deprecating humor fills out his stage banter and interviews. But when the bearded Duluthian who dresses like he's been fixing his truck all afternoon — and he might've been — starts singing, he's not backing down. "Ain't No Grave Gonna Hold My Body Down" is an 80-year-old song that he recorded a few years back, and performs live with a vengeance. Combining folk, blues, and gospel into his delivery, Parr brings about something as raw as the earth that might well be under his fingernails. In so much of his picking and singing, he conjures the voices of the hard-working and unheralded who built what we now know as music, ensuring that their graves can't hold them down either.