In the crowded field of drone-based ambient composers, Los Angeles’s Byron Westbrook stands as one of the most rigorous and interesting. One long-form piece he did, Threshold Variations, manifested, in his words, an “immersive environment” in which drones and field recordings wax and wane like aural mirages, inducing sublime dream states. For this gig, Westbrook will perform Surface Variants, an extended composition using analog and digital synths, field recordings, and tape manipulations to examine the concept of the “sonic afterimage.” The excerpt I heard contains abrupt transitions and episodes ranging from quiet animal sounds to corrugated noise bursts. Seattle’s N Chambers is returning to the live fray after months of cancer treatments. He remains, as I've been yelling at you for years, one of America's most engrossing synth composers. Hit panabrite.bandcamp.com for hours of sonic enlightenment. by Dave Segal