The Austrian quartet Polwechsel treats music like an unfenced field: no sound is off-limits. Double bassist Werner Dafeldecker, cellist Michael Moser, guitarist Burkhard Stangl, and English saxophonist John Butcher (who’s replaced trombonist Radu Malfatti) are best known in avant-garde classical and free-improv circles, but between them they’ve played with turntablists, rock bands, and mellow jazz combos in venues ranging from art galleries to the top floor of the Empire State Building. Dafeldecker also “plays” electronics, and both he and Moser sometimes switch to tabletop guitar. The microscopically detailed improvisations on Polwechsel’s two CDs for the Swiss label Hat [Now] Art teem with crackling static, spikes of guitar feedback, the rustling of fingertips on strings, and bubbling, reedy exhalations, all atop bowed acoustic drones. Dafeldecker and Moser also compose intricately layered pieces that use the same vocabulary. Polwechsel last played Chicago three years ago, but members have visited several times since, cementing a connection to local bass clarinetist and composer Gene Coleman; the entire group is returning this week to participate in his Sound Field festival (see Post No Bills). On Friday and Saturday, they’ll share the stage with Coleman’s Ensemble Noamnesia for two concerts at the Renaissance Society. The first program consists of music by Austrian composers such as Olga Neuwirth and Beat Furrer; the second includes Stangl’s new opera, Moon of Venus/Part III/Chicago, and a set by Polwechsel alone. On Sunday afternoon at HotHouse, Polwechsel joins saxist Boris Sinclair Hauf and computer musicians Karlheinz Essl (see Spot Check) and Christof Kurzmann, and on Tuesday a new group called Pos/Neg–Stangl, Moser, Dafeldecker, Coleman, and two local guests, oboist Kyle Bruckmann and trumpeter and electronicist Ernst Long–makes its debut improvising and playing works by Coleman, Dafeldecker, and Nicolas Collins. Friday and Saturday, 8 PM, Renaissance Society, Cobb Hall, University of Chicago, 5811 S. Ellis; 773-702-8670. Sunday, 5 PM, HotHouse, 31 E. Balbo; 312-362-9707. Tuesday, 7 PM, ballroom, School of the Art Institute, 112 S. Michigan; 773-973-2501. BILL MEYER

Art accompanying story in printed newspaper (not available in this archive): photo/Jerzy Palacz.