When bassist Luc Klaasen left the Ex in 2002 the Amsterdam collective lost what had been for 19 years a crucial component of its sound: his roiling, distorted parts did so much work that guitarists Andy Moor and Terrie Hessels could range far afield into dissonant experimentation without eviscerating the songs. By bringing in Rozemarie Heggen, a double bassist with a deep classical background, the band chose to create a new role rather than fill Klaasen’s old one. As the new Turn (Touch and Go) establishes, it was a brilliant move: this is the best Ex album in at least a decade. With her warm, patient lines and muscular arco work (recalling the band’s superb collaborations with cellist Tom Cora), Heggen gives the music a newly spacious dynamic and leaves the group sounding stronger and more purposeful than ever. The bulk of the 14 songs on the two-disc set display the Ex’s typically furious attack–the guitarists peel off tough rhythmic riffs, string-tangling freak-outs, and coloristic noise bursts amid the fierce martial beats of drummer Katrin Bornefeld and the ranting vocals of G.W. Sok. The band’s outrage at U.S. unilateralism fuels much of the material, from the hilarious Ollie North-style equivocating on “The Idunno Law” to the searing indictment of “Henry K,” and as usual Bornefeld takes the mike for a few numbers, including the groove-driven anticapitalist snipe “Prism Song” and a version of the Eritrean folk song “Huriyet.” The band also pays homage to the great Ethiopian saxophonist Getatchew Mekurya, with guitar lines recalling his pentatonic improvisations, and samples electrified thumb piano courtesy of the Congolese band Konono. The local free-jazz trio Triage opens with a set celebrating the release of their third and finest album, American Mythology (Okka Disk). $12. Wednesday, September 15, 9:30 PM, Empty Bottle, 1035 N. Western; 773-276-3600.

Art accompanying story in printed newspaper (not available in this archive): photo/courtesy Touch & Go.