Violinist Ben Jacobson is fully aware of how lucky he is.

The 24-year-old leader of the L.A.-based Calder Quartet is just as surprised as anyone in the music community at the young ensemble's critical and commercial success. Very few U.S. string quartets can support themselves independently, but the Calder Quartet -- in the middle of a two-year residency and with bookings through mid-2005 and a recording in the works -- has already established its credentials nationally, even though its four members just graduated from college last year.

"I think it's pretty rare what we have going on," said Jacobson, who brings the Calder Quartet to his former hometown of Carlsbad this weekend for the Carlsbad Music Festival. "I know a lot of people who are 10 years older than me who haven't had these kinds of opportunities. They've worked a lot harder and success has come a lot slower for them. Maybe some of it is luck, but I also think we have something special."

Formed in 1998 at the University of Southern California's Thornton School of Music, the Calder includes the under-25 quartet of Jacobson, violinist Andrew Bulbrook, violist Jonathan Moerschel and cellist Eric Byers. The group named itself for the late American sculptor Alexander Calder, whose whimsical mobiles were described by existentialist writer Jean-Paul Sartre as "lyrical inventions, technical, almost mathematical combinations and the perceptible symbol of nature."

A regular on the music festival circuit, the quartet won the 2002 Coleman Chamber Ensemble Competition, has appeared on National Public Radio's "Performance Today" and was lauded by L.A. Weekly music critic Alan Rich as the ideal future candidate for Los Angeles' official resident quartet. Now resident at the Colburn School of Performing Arts in L.A., the Calder's wide repertoire ranges from Bartok, Beethoven and Brahms to Janacek, Haydn, Shostakovich and Spohr.

Jacobson credits the group's success to its shared musicianship, compatibility and temperament.

"We're all excellent musicians, but also we all have different strengths that complement each other," he said. "Overall, the group has a strong strategic sense of how to plan and publicize things, and that has helped us a lot. Another big thing is that we're all likable people. We get along well with most of the people we know, and we've never had any falling-outs between our members. We're fortunate in that way."

The road hasn't been without its bumps, though. Moerschel kept up his concert commitments all last year while his wife, pianist Eugenie Ngai, was dying of cancer. (The work, he told the Los Angeles Times, was therapeutic.) And Jacobson admits that the group's intense practice schedule leaves him little time for friends or family.

The Calder Quartet will have little time to relax in the coming months. This summer's schedule includes the Aspen, Norfolk and Grand Canyon music festivals, a recital in Hollywood in September with pianist Claude Frank, two competitions and a skills-polishing trip to Itzhak Perlman's music camp in the Hamptons.

Jacobson said it's crucial at this point of the quartet's musical life to build learning time into its schedule.

"We still need to develop our repertoire and at the same time perform the heck out of the pieces we know," he said. "It's a juggling act, and we're doing pretty good and keeping all the balls in the air."

While solo opportunities with orchestras are tempting, the quartet is committed to playing together as a group. Fortunately, that has been a financially viable option with the Colburn residency, which continues through the 2004 season. After that, Jacobson said, the opportunities are nearly limitless.

"It's almost a dream how ascendant this whole thing has become and how many opportunities keep coming," he said. "We just want to ride it and work hard and enjoy it."