Since the early 80s, Arizona’s Sun City Girls have done darn near whatever they wanted, exploring whatever musical traditions have captured their interest. That they pull off so many disparate ideas is a credit to their collective technical skills, though the unpolished quality of their records can make it hard to discern just how deep that well of talent really goes. Richard Bishop’s solo guitar albums help clarify matters. On his solo debut, Salvador Kali (Revenant, 1998), he overdubbed guitars and piano to display a typically broad range of approaches, including makeshift Gypsy jazz, Indian ragas, and ragtime. On Improvika (Locust), released last year, he sticks to steel-stringed acoustic guitar, channeling the fingerstyle traditions of John Fahey, Robbie Basho, and early Leo Kottke–and their interest in Southeast Asian music–without sounding like he’s imitating any of them. He injects most of the pieces with a fierce intensity that’s not far removed from his more extroverted electric work–complex tangles of melody gush forth in high-velocity torrents of resonant fingerpicked notes. The casual charm of the recording echoes the spontaneity of Sun City Girls–flubbed notes are left intact–but the pieces are tightly composed. Bishop takes a few detours from the primitive-guitar concept–the brief “Cryptonymus” recalls the spiky dissonance of Derek Bailey’s improvisations, and the closer, “Skull of Sidon,” alternates between a short, driving riff and some violent chord thrashing–but throughout he’s discovering new modes of expression, even within well-defined traditions. The Singleman Affair and Rope open. Mon 4/18, 9:30 PM, Empty Bottle, 1035 N. Western, 773-276-3600 or 800-594-8499. Free.