Over the past three decades, guitar visionary Bill Frisell has created one of improvised music's most original styles, built on elegiac timbres, stately phrasing, and meaningful meandering. (For years a favorite line in Manhattan avant-jazz circles was that Frisell had been "raised by deer," and even his most slashing, electronics-driven work retains the gauzy textures and gentle dream logic that have become his trademarks.) But despite the newsmagazine kudos heaped on his Americana-inspired discs of the past decade, starting with Nashville in 1997, some of us can't see the emperor's new clothes--we long for the otherwordly, motive beauty of his earlier playing, both on his own albums and on the hundreds he's recorded with genre benders like Tim Berne, Paul Bley, Paul Motian, and John Zorn. Last year's Unspeakable (Nonesuch) has gone a long way toward answering that desire: without abandoning his spacier instincts, Frisell has anchored his improvisations in hard beats and solid grooves, sometimes augmented with horns and strings, and recaptured the combination of easygoing stroll and artistic urgency of 1985's Rambler and 1992's collaboration with John Scofield, Grace Under Pressure. The five-piece Unspeakable Orchestra backing Frisell here consists of his longtime rhythm section, bassist Tony Scherr and free-limbed, forceful drummer Kenny Wollesen, and the album's "858 Strings"--Hank Roberts, one of the world's top three improvising cellists, violist Eyvind Kang, and violinist-vocalist Jenny Scheinman. The Bad Plus, the acoustic piano trio that thinks it's a rock band, opens the show. Fri 5/6, 8 PM, Orchestra Hall, Symphony Center, 220 S. Michigan, 312-294-3000 or 800-223-7114, $19-$42. All ages.