In his Orchestrion, Pat Metheny has 40 instruments at his fingertips

"THE SORCERER'S Apprentice" has nothing on Pat Metheny.

In the best-known, Disney cartoon version of the tale, a little mouse of a guy waves a magic wand and brings a bunch of brooms to life to fetch pails of water.

When master jazz guitarist/composer Pat Metheny takes to the crowded-with-equipment stage of the Keswick tomorrow night, he'll be steering his big-sounding show all alone, with the wave of hands over guitar strings and knobs, and the triggering of foot pedals. All to kick-start his MIDI-computers and bring to life an "Orchestrion" of 40 mechanically controlled instruments - hammered-on keyboards, vibraphones, bass- and guitarbots, tons of percussion and even a cabinet full of glass bottles blown with compressed air "for added warmth."

This will accompany Metheny's very alive guitar work in a lush new suite of songs, plus gems from his deep catalog.

"There's never been a concert like this," marveled the musician in a recent, late-night conversation. "It's really fun to watch and experience, a great date night thing. Unlike most shows, there's a lot to talk about, with a certain amount of debate. I've been doing concerts for 37 or 38 years, and I've never had audience reaction quite like this.

"People are freaking out."

As previewed on Metheny's "Orchestrion" album deploying the same, um, ensemble, the now meditative, now bluesy, now bopping or dramatically soaring music sounds very fine and "in the pocket" with the richly lyrical stuff this guitarist normally develops with his Pat Metheny Group - minus only the chanting vocals.

"People don't really sense what's going on until they actually witness the Orchestrion show," Metheny noted. Even then, the seeing is almost disbelieving - watching, say, the subtle "swing" of robotically armed brushes on cymbals, or the dynamically varied attack of trigger fingers on a keyboard, made possible by the latest refinements in solenoid motor technology. (For those of you who slept through class, that's an electromechanical device that converts energy into motion.)

To help grasp the obvious, LED lights pulse as the mechanisms play. But there's no wheezing and clunking. All you hear are natural-sounding acoustic instruments.

"I wouldn't have done this if it couldn't groove, if it didn't have a certain warmth, a tonal quality," Metheny noted. "And if I didn't have the ability to change things from show to show and not just in my solos. I can program scripts, events, the tempo and the length of passages on the fly. So it's a living, evolving, breathing environment."

While some critics have carped that Metheny's Orchestrion is a "mere novelty" and yet another stab in the heart of live performance bands, the mastermind sees his finely machined music differently.

"It's a very sincere connection to something that has interested me since I was literally a kid, and it fits with the odd skill set I've developed," shared the wizard. "I live this music-slash-technology life, with wires and knobs as central as strings and picks. Technology is no big deal to me. It's transparent, just the way a mouthpiece is to a trumpet player. But it would take many hours for me to explain how everything here is done."

Pat was a small child when he first encountered a magical player piano in the basement at his grandparents' house in Wisconsin. "My mom's dad was a professional trumpet player and a singer in barbershop quartets. It was an Upper Midwest-Scandinavian-Polish-German thing, and somehow a player piano figured into that.

"This instrument was just fascinating to me. I'd spend every summer vacation underneath the thing, trying to figure out what was going on. I even pulled it apart once. My cousin was with me and freaked out, he reminded me recently, but I eventually got it back together."

An especially strong presence in family parlors at the turn of the 20th century - competing with the first recorded music on Edison wax cylinders - player pianos were manipulated by paper rolls coded with a series of punched-out holes, with the human "player" merely pumping away on the mechanism-moving foot pedals.

"Most player pianos had no dynamic range. They were just loud, which is why people would go screaming from the room after three minutes," Metheny said with a laugh. "Later, more sophisticated piano rolls with six levels of dynamic range were developed, which allowed notable pianist/composers of the day like Sergei Rachmaninoff to record their performances in well-reproducible form" available on CDs today.

In the final years of the phenomenon, piano rolls were finessed to trigger connected percussion instruments, creating the original concert orchestrions.

With his own work, Metheny has been into the merging of technology and music since the late 1970s when he started working with guitar synths, allowing him to modify his picked guitar lines to sound like, say, a riffing trumpet.

"But that tech had a lot of limitations, for the fundamental reasons of physics - what happens to the note, how it's modified in tone and pitch. And while synthesizers do provide a sense of orchestration, it's nothing like what happens with real instruments moving air," he argued.

In the 1990s, "it was hip to have a laptop [computer] on stage, but that's the corniest thing in the world now."

Metheny's Orchestrion has been in development since October 2006. "The night I made the call that I was going to do this was the night I played Steve Reich's 'Electric Counterpoint' for his 70th birthday concert at Carnegie Hall.

"It's a 12-part piece that I played live with accompanying tape recordings. At the end, I got an incredible reaction, this big ovation. And I thought, 'Wow, I just played with a tape at Carnegie Hall, and if that's cool, if we live in a world where that's OK, then I'm going to do this.'

"I'm always getting people to wire and build weird things for me, so I gave them the go-ahead."

From the git-go, Metheny stipulated that the gear had to be ultrareliable and built to travel. "We recently did 42 shows in Europe in 42 nights. And amazingly, the level of equipment failure was very low - no worse, on average, than the breaking of guitar strings. Of course it's a bummer when it happens at the beginning of a show, but when it happens at the end [as it did in Paris during his show-capping encore of "Phase Dance"] you just go into solo mode and then say, 'Goodnight.' "

As for the critics who've carped that he should just play with live musicians if he wants a natural sound, Metheny draws his own analogy to animation.

"It's like somebody watching 'Bambi,' then saying, 'That was a good movie, but why didn't they get a real deer?' They're missing the point. It's not a substitute. It's a medium of its own. Of my own."

Pat Metheny Orchestrion Tour, 8 p.m. tomorrow, Keswick Theatre, Easton Road and Keswick Avenue, Glenside, $52.50, 215-572-7650, www.keswicktheatre.com.