In solo recordings, this Swiss guitarist and sound artist often forces his long-form abstractions into overly familiar quiet-loud-quiet structures. The 19-minute “Thermo,” from 2005’s Effacement, starts out as a slow-growing collage of electronic glitches, like a petri dish seeded with squiggling static. Then, at the six-minute mark, Korber finds the overdrive switch, transforming these sounds into lacerating white noise, like an overmatched old TV pulling in a UHF channel that’s signed off for the night; finally the level drops and everything just fades away. I much prefer his collaborative work, where the shapes of the pieces seem driven by decisions the players make on the fly. On the recent Zurcher Aufnahmen (released by the local Longbox label), Korber, Jason Kahn (synthesizer, percussion), and Christian Weber (upright bass) draw from a narrow palette of sounds–electronic hums, subtly resonant clanging, the occasional bowed bass note–and allow them to swell and recede in response to unpredictable details that arise from their improvisations. Tonight Korber headlines in a trio with Chicagoans Olivia Block and Adam Sonderberg; Guillermo Gregorio, Brian Labycz, and Jason Roebke play second and Salvatore Dellaria opens with a solo set. a 8 PM, Elastic, 2830 N. Milwaukee, 773-772-3616, donation requested. A