Most days, he’s known as Alan Bishop, former member of experimental trio Sun City Girls and co-founder of Sublime Frequencies, the peerless label that re-released music and field recordings from Africa, Asia, and the Middle East. Sometimes, like tonight at Mississippi Studios, he’s known as Alvarius B., creator of arch blues, blasted psychedelia, and unhinged folk. Bishop will take the stage tonight for two sets: a solo run and a collaboration with Egyptian ensemble the Invisible Hands. by Robert Ham