Under its founder, Hal Russell, the NRG Ensemble planted many of the seeds that eventually bloomed into Chicago’s bustling free-jazz and improvised-music scene, so there’s a certain irony in the fact that the group rarely performs these days. The old NRG combined madcap humor, raucous energy, an inviting informality, and a nonchalant virtuosity into a woolly amalgam that attracted music fans who ordinarily might have had little interest in free jazz. It was not a well-oiled machine, but it sounded great even when all of its wheels were flying off. When Russell died in 1991, Ken Vandermark joined the group and longtime member Mars Williams took over as the quintet’s nominal leader. On its three subsequent albums, including the brand-new Bejazzo Gets a Facelift (Atavistic), the NRG has incrementally tightened its focus, replacing Russell’s charming sloppiness with a sharpness that might seem better suited to a string quartet, were the music not so muscular and wild. The new album contains its fair share of the group’s trademark high-octane burners, in which drummer Steve Hunt prods vicious sax sparring between Williams and Vandermark over the acidic wash of Brian Sandstrom’s guitar, but more impressive is the group’s newfound ability to incorporate space. The lovely “Cakewalk,” for example, is filled with tender solos (Kent Kessler’s woody bass, Hunt’s subdued marimba) and duo passages (the seeking clarinet and bass clarinet of Vandermark and Williams), but even when all five play at once there’s a sensitive awareness among them. Most rewarding of all are the album’s four free improvisations. To my knowledge this is the first time the group has ever committed pure free improv to disc, and the results testify to the level of intuition and interaction these individuals have developed over the years. Wednesday, 9 PM, Empty Bottle, 1035 N. Western; 773-276-3600. PETER MARGASAK

Art accompanying story in printed newspaper (not available in this archive): photo by Sandy Sager.