In an alternate universe, Tom Walsh might be the world's foremost classical trombonist, performing with high-profile orchestras around the globe and recording for the prestigious Deutsche Grammophon label. In the dimension we inhabit, however, he leads a versatile but little-known improv group, records for the unjustly obscure Ambiances Magnétiques imprint, and rarely has to don a tuxedo or tails. That's just the way he likes it, and it's all thanks to a Seattle-based guitarist and a head full of fragrant smoke.

Neither Jimi Hendrix nor Kurt Cobain were responsible for Walsh's change of direction. Instead, the sonic innovator who opened his mind to the whole world of music was Ralph Towner, de facto leader of the band Oregon and a composer whose output falls somewhere between contemporary classical music, modern jazz, and avant-garde folk.

As Walsh tells it, his boyhood friend Jim Vivian--now an acclaimed jazz bassist in his own right--is to blame. "We went to see Ralph Towner and Oregon, and afterwards we went back to Jim's, smoked a big Thai-stick joint, and listened to Ralph Towner's Solstice," the trombonist explains, calling from his Montreal home. "And I had an epiphany. It was my first 'ta-da' moment, musically, because there were moments where I couldn't tell if what they were playing was written, or if they were improvising it. And I just got totally horny for that. I thought 'That's what I want to do.' "

At the time, Walsh was 15, and already the first-chair trombonist with the Newfoundland Symphony Orchestra. But it wasn't long before he headed to Toronto's Humber College to get an education in jazz, and 25 years later he's still mixing up improvisation and composition with his NOMA septet. This is no ordinary jazz band, however: it's more like two separate guitar-bass-and-drum trios--one oriented toward funk and fusion, the other more attuned to free improvisation and contemporary classical music--with Walsh directing things from the middle.

Judging by the group's new Diversion CD, the strategy works. Sometimes formal, sometimes funky, and sometimes sweet, NOMA covers a lot of stylistic ground without losing any of its own identity. The band--at the Vancouver East Cultural Centre on Thursday (July 1)--also accomplishes Walsh's goal of marrying the conceptual integrity of composed music with the emotional freedom of improvisation.

"When I'm writing," he says, "I reach points where the music can go in a number of different directions, all of which are good and all of which would satisfy my sensual desires for the song. So why do I have to finish it? The musicians are there to co-enjoy the sensuality. That's where my approach comes from: I want everyone in NOMA to be my Billy Strayhorn."

Walsh doesn't refer to Duke Ellington's long-time arranger and writing partner lightly; in some ways he sees himself as a latter-day Ellington, making serious music but delivering it with joyous energy. "Duke approached jazz like a pop musician would," he says. "He wanted everyone to feel like they're playing the melody." And while the trombonist's melodies are considerably more angular than even Ellington's wildest work, their sophistication and power are no less apparent.