Newgrass this is not. Ralph Stanley's primitive mountain soul predates even bluegrass pickers. Those relative upstarts have been around since the 1930s and 40s, but Stanley's plaintive soundand the 81-year-old Stanley himselfhearken back to the Appalachian hills even earlier. His claw-hammer banjo style forgoes the lightning-quick picking of bluegrass virtuosos for sharp, dry chord blasts that punctuate his lyrics. And it's the singing that you come for anyway. After decades of touring in obscurity, Stanley found modest fame with a tremulous a cappella rendition of the dirge "O, Death" for the 2000 O Brother Where Art Thou? soundtrack. Stanley's uniformed Clinch Mountain Boys guarantee performances aren't entirely somberhis mandolin-playing grandson, Nathan Stanley, 16, may even deliver a joke or two. It's direct music, from before the advent of irony. At a rainy Indiana campground two years ago I watched Stanley and his band sip honey-laced coffee backstage. To sweeten their voices, I was told. When the show began, old-timey sweetness and old-timey bleakness never blended so well. With John Reischman and the Jaybirds. Moore Theatre, 1932 Second Ave., 443-1744, 7:30 p.m. $23-33. All ages.