Over a dozen years and a deluge of releases, Cincinnati multi-instrumentalist C. Spencer Yeh (who heads Burning Star Core) has zig-zagged across subterranean strata of noise, drone, avant-rock, and minimalist composition, summoning images of violinist Tony Conrad collaborating with Vibracathedral Orchestra. Challenger finds Yeh at his most compositionally disciplined. Drones still dominate, but they‘re sculpted with a rigor and melodic nuance that recalls Stars of the Lid and William Basinski. For Yeh, refinement doesn‘t equal staidness, rather it accentuates his considerable compositional gifts. Additionally, Yeh‘s keen ear for odd sound sources (warped mouth harp, uninflected uhs, cheetah growls, face slaps) lends surprising textural chiaroscuro and piquant Dada flavor to his eloquent drone poems.