Once upon a time, gypsy violinists Fabrice Martinez and Ursula Knudsen traveled by mule caravan through small villages in Europe.

Now, they mostly travel by Eurovan. But the musical experience -- authentic gypsy melodies tempered by an American sensibility -- hasn't changed.

Performing as Fishtank Ensemble, the couple -- now married and joined by flamenco and gypsy jazz guitarist Douglas Smolens, a native of Guadalajara, Mexico, and Serbian slap bassist Djordje Stijepovic -- will bring their global sound to Lancaster on Wednesday for a special performance at the Pennsylvania Academy of Music.

The group's name, Knudsen explains, came after a one-off performance in Los Angeles that was never intended to be a regular thing. "But people just went crazy," she said. "And someone asked me for the name of our band. Band, I thought? What band?"

Fishtank, which was the name of a cluster of apartments where she and some of her musical friends lived at the time, was the first thing to come to her mind, Knudsen says.

"I went through years of not liking the name. Why, oh why did I say that? But now I love it. It doesn't define us in any way ... which is actually very liberating."

Fishtank Ensemble is certainly making a splash with its energetic performances that range from wild French jazz, tango and django to Transylvanian gypsy anthems and klezmer. LA Weekly recently called them "one of the most thrilling young acts on the planet."

"We love this music. We love this scene. It's a passion," Knudsen says.

"It's very popular right now. I'm not sure why," she adds. "Gypsy music has a wild, untempered energy ... that coincides very well with the punk movement. It's pretty intense party music. Who doesn't respond to that?"

French native Martinez, who criss-crossed much of Eastern and Southern Europe over seven years of travel with the caravan band Croque Mule, drives Fishtank Ensemble's sound with his frantic violin. "He was used to playing all day, every day," Knudsen says. "He'd collected songs from all over Europe. He traveled with his family, they all played music and had lots of adventures."

A classically trained vocalist with strong operatic influences, Knudsen -- a native of Sacramento, Calif. -- sings in several languages including Hungarian, Serbian, French, Romanian, Spanish and, occasionally, English. Besides violin, she also plays the musical saw and banjolele. "I consider myself an interpreter," she says. "A lot of what do is traditional, although it's arranged by us to be more palatable to an American audience."

Some listeners, for instance, might not be able to sit still through an hour-long Hungarian suite. Fishtank Ensemble might transform the piece into a five- or six-minute song.

"People will have a very good time. They're going to want to dance," Knudsen promises. "They've never heard anything like this."

Gypsy music involves "a lot of colors, a lot of imagination," she says. "It always gets people really, really excited. We mix it up enough to give our audiences a huge variety ... and by the end of a performance, we're shooting off the ceiling."

The band has released two CDs to date -- Super Raoul in 2005 and Samurai Over Serbia in 2007 -- and has toured widely. Somehow, Martinez and Knudsen also found time to stow their caravan wagon in Los Angeles and have a son together. Ezra, nearly 4, is already showing musical inclinations, the proud mother says, although "we don't want to push him."

Even today, though, Knudsen says she and Fabrice yearn for the simplicity of their caravan days.

"It's a wonderful thing," she said. "And the people are wonderful, stepping over each other to be the ones to bring you water, to bring hay for your mules. When we left Italy three years ago, we always hoped we'd come back someday.

"I figured we could always do this, but our lives have changed so much. All of a sudden, we have a kid and we're living in North Hollywood and we're touring all the time. But I still have hopes that we'll do it again."