Richard Buckner is a bear of a man. At over six feet tall, he could make an imposing center for the Alt-Country Alt-Stars basketball team. In concert, he hulks over his acoustic guitar and mic stand, thus filling the stage in the same unassuming but forceful way he inhabits his songs. While Buckner is often accompanied by a bare-bones, propulsive backing band on his records (like last year's wonderful Meadow, which features Guided by Voices alum Doug Gillard), on tour he normally prefers to go it alone. But not this time: The instrumental collective Six Parts Seven will be backing him and playing its own set, meaning folks have the rare chance to see Buckner stretch out a bit by adding touches of ethereal Americana to his quavering delivery.