Gillian Welch is still best known for her stunning contributions to the O Brother, Where Art Thou? soundtrack; her vocals with Alison Krauss on “I’ll Fly Away” are spine-tinglingly gorgeous. But Welch was apparently uninterested in being lumped in too closely with the old-timey folk crowd; on subsequent releases, she has tried on a more polished, relatively modern folk-pop sound for size. It’d been about eight years since the last proper Welch album when she returned earlier this summer with The Harrow & the Harvest, which should please fans of her early Appalachian folk and bluegrass. Her frequent collaborator, David Rawlings, joins her on the tour.