Standing on the waning edge of the alt-country revival--the end of yet another musical cycle that seems stalled in a glut of retro-parody--it's hard believe a band could still make Depression-era music seem as fresh and vital as the day it was spawned. Halfway into their first set at the Sept. 9 Roots Café , we realized the Tarbox Ramblers didn't need bolo ties or disingenuous hiccuping. They proved traditional doesn't have to mean hokey. Plumbing the depths of pre-war ballads, blues, and hillbilly music via the Harry Smith Anthology of American Folk Music, the Boston-based quartet shook the old church on down. They looked like the Smithereens, but played their antique instruments like an amped-up burlesque band--gritty, earthbound, and ethereal at once. The intimate stone walls of St. John's United Methodist Church in Charles Village provided the perfect backdrop and acoustics. We couldn't help being drawn closer as guitarist Michael Tarbox sang "The Cuckoo," an old standard about a glamorous but alcoholic woman, accompanied by the punctuating wails of fiddler Daniel Kellar. As the Ramblers worked through two sets of plaintive ballads and rambunctious and danceable rave-ups, Tarbox's gruff baritone conveyed the universals: murder, betrayal, bad luck, and hopelessness. In lesser hands, these songs would fall on the floor--more phony retro-junk, forgotten tomorrow. But the Ramblers transported us: For a while, there was no past or present. What people sang about then can still punch the gut today.