By Mark Swed

Thirty is a respectable age for a string quartet, if hardly a record. But here's one not likely to be broken any time soon: Since its first concert in 1973, the Kronos Quartet has premiered more than 450 works that were written or arranged for it. Kronos has, in effect, given the world a new string quartet every three weeks, steadily, for three decades.

This spree began 29 years ago with an exchange of a bag of doughnuts with composer Ken Benshoof for his Traveling Music. It has continued by inspiring new work from a host of major composers-Elliott Carter, John Cage, Terry Riley, Morton Feldman, Philip Glass, Louis Andriessen, Steve Reich, Henryk Górecki, Sofia Gubaidulina, John Adams, Peter Sculthorpe, John Zorn, Osvaldo Golijov, Astor Piazzolla, and Tan Dun, among them.

But that is only part of the story of a string quartet whose name is a snappy spelling of the Greek word for time, chronos. Musical America's Musicians of the Year have made an unprecedented effort to encompass and personify their time in a broader sense than might ever have been thought possible. Before Kronos (as part of that personification, the players dislike being called the Kronos), the string quartet had come to represent a select refuge from the hurly-burly of the wider world of music. Without discounting the meaningful value or purity of such experience-and there is nothing purer or more otherworldly in all the chamber-music literature than the mesmeric, meditative five-hour quartet Morton Feldman wrote for it-Kronos has nonetheless boisterously broken down nearly every conceivable genre barrier that ever existed for the string quartet.

Once it shocked by playing arrangements of rock and jazz. And over the past two decades, Kronos has become famed for its restless scouring the globe for string-quartet material, foraging for composers and collaborators from Vienna to Veracruz, Bombay to Beijing, Buenos Aires to Barstow, Tehran to Tunisia, Novi Sad to Nova Scotia, and Moscow to, most recently, Mexico City. In the process it has changed our perception of not just what a string quartet can do and be, but what music can-and, perhaps, must-be, now, in the 21st-century global village.

Foraging may be the wrong word, because what makes Kronos exceptional is not so much collecting new work as the ensemble's participation in a vast range of musical cultures-an interaction that causes it to transform all that it plays but also to be transformed by it. One perhaps extreme but particularly telling example of such transformation can be found in Kronos's performance of "Perfidia," that 1940s Mexican pop song popularized as "Perfidy" by Nat King Cole.

One day wandering the streets of Mexico City, David Harrington, Kronos's first violinist and founder, heard a seductively eerie, high-pitched instrument he couldn't identify. It was the sound of a one-armed street musician, Carlos Garcia, playing old standards by blowing on the edge of an ivy leaf, and Harrington immediately resolved that Kronos had to perform with him. And so it did on its recent Nonesuch recording of Mexican music, Nuevo, in a kitschy arrangement of "Perfidia" by Steven Prussman that recalls the saccharine old mood music LPs by 101 Strings.

Yet to hear Kronos play this arrangement of "Perfidia" live turns out to be a gripping, many-layered postmodern musical experience. The 101 Strings sound was achieved by extensive overdubbing, a process in which Kronos became proficient when Steve Reich asked for several Kronoses in Different Trains. In concert, a live Kronos plays with unexpected fervor against a schlocky version of itself, as an ironic comment on the whole concept of background music. Garcia's playing is elegant and nuanced but also weird, reminiscent of electronic music. On top of all this are Mexico City street sounds on the tape, which add an Ivesian effect, creating a sense of this music existing in a specific time and place outside the concert hall. The result is a complex musical experience full of discovery.

I've followed Kronos since 1978, when it arrived as a quartet in residence at Mills College in Oakland. In those early years, none of us was exactly sure what to make of this foursome. There was no question about the electricity and fire in its playing and the palpable thrill it demonstrated in its preoccupation with the new. The programs back then included challenging mainstream work (say late Beethoven), 20th-century classics (Shostakovich, Berg, Bartók, Ives, etc.) and always something new. It was a matter of hot debate whether its arrangement of Jimi Hendrix's rock anthem, "Purple Haze," indicated hip irreverence or string-quartet renewal.

The ensemble's look, though tame by today's standards, startled as well. Violinists David Harrington and John Sherba, violist Hank Dutt, and cellist Joan Jeanrenaud wore matching three-piece suits with the wide lapels and ties then in style. Soon Harrington's hair would become spiked, as were Jeanrenaud's heels. Every concert was an adventure and not to be missed.

Kronos had been formed five years earlier by Harrington, who, as a youth growing up in Seattle, fetishized string quartets in a way that other teenage boys in the early 1960s did rocket ships; but he was also caught up in the energy of '60s popular music. When the draft threatened, he joined an orchestra in Canada. Upon his return to Seattle, he heard George Crumb's hauntingly ritualistic anti-war Black Angels on the radio. It contained such strange sounds that he didn't even recognize it as quartet music at first, but he felt an overwhelming desire to play it. At 22, he started a group.

The first concert was at North Seattle Community College, and soon afterwards the fledgling Kronos gave the Northwest premiere of Black Angels as well as the first performance of Benshoof's Traveling Music, a likable 18-minute piece, incorporating easygoing references to blues and folk songs, by Harrington's high-school composition teacher.

For its first five years, Kronos was a quartet in flux. Players came and went as Harrington ran the Quartet out of his one-room Seattle apartment and later at the State University of New York, Geneseo, in upstate New York. But it was only upon accepting the residency at Mills that Kronos solidified its membership and found its identity. The medium, it should be recalled, was pretty much off the map for most younger composers interested in avant-garde, pop, jazz, and world music. At any place other than Mills (whose famed music department was one of the most venturesome in the country), Harrington's belief that Kronos could change all that would likely have seemed slightly mad.

The most lasting consequence of Kronos's two years at Mills was its encounter with Terry Riley, then the star composer of the department. Best known for In C, which launched the minimalist movement in 1964, Riley had turned his attention to Indian music and hadn't used conventional notation for nearly 15 years. But Harrington persistently cornered Riley in the hallways and at the school cafeteria until Riley wrote out some sketches for a sweet, ten-minute score, G Song. The composer then invited the Quartet to his remote ranch near Lake Tahoe to work out the lyrically lapping repetitions that left phrasing, dynamics, and tempo up to the players. The experience proved a breakthrough for Riley and Kronos.

A student of exactingly precise intonation of Indian singing, Riley disliked vibrato, and he encouraged the players to replace its conventionally emotive style of vibrating the strings with a more expressive use of the bow. This became the source of the unmistakable Kronos sound. Lessening vibrato not only allows the players to better zero in on pitch, but the adept use of bow for timbral effects provides a striking sense of body and propulsion.

Riley also inspired Kronos to think like active collaborators in all they played, an attitude that has led to any number of distinctive Kronos interpretations of other works. I once witnessed a rehearsal of Lutoslawski's String Quartet, for which the composer was present. He was shocked, never having imagined this much-performed piece played quite so viscerally. Thinking about it for a long time, he said-in a remark that echoed what Schoenberg had once said when he heard the Juilliard String Quartet play his music-"Don't change anything!"

Riley's overall influence upon Kronos has gone far beyond technique or style, however. He and Kronos developed a consistently deep, ongoing relationship that has led to a significant body of important and groundbreaking work, the latest piece being the new NASA-inspired and -commissioned, evening-long quartet, Sun Rings, which includes manipulated electronic sounds of plasma waves recorded in space as well as a 60-voice choir. But perhaps the most far-reaching consequence of Kronos successfully persuading Riley to become a string-quartet composer was to reinforce Harrington's audacious belief that string-quartet music might suit just about any kind of composer.

Emboldened, Kronos struck out on its own in 1980, establishing itself in San Francisco as it set out to change everything people had thought a string quartet could, or should, be. Harrington sought out composers with a dizzying zeal, and, in doing so, the Quartet soon gained an extraordinary trust from composers who delighted in the players' fearlessness. The most astonishing example of this was when Morton Feldman presented Kronos with the bombshell of his five-hour Second Quartet in 1983. The players trained like athletes, dehydrated for the performance (there are no breaks), and triumphed, proving the work to be a masterpiece that readily takes a listener into new planes of consciousness. So great is the physical stress of playing this quartet, Harrington says that it would take him about two weeks to recover from a performance. But Kronos proved that it could be done, and now younger ensembles have followed in its wake.

Inspired by Kronos's try-anything eagerness, Steve Reich was able to experiment with a new way of composing in his 1988 quartet, Different Trains, recognized as one of the most effective art works in any medium to deal with the Holocaust. After a painstaking process of overdubbing four separate string-quartet tracks, Kronos had to carefully synchronize its live performances with those recordings, along with prerecorded voice samples that electronically turned into musical speech. The result is an ingenious musical documentary contrasting the differences between the cross-country train trips the composer took in his youth and those taken by many Jews in Europe.

It was also in 1988 that Kronos's practiced persistence broke down the resistance of Henryk Górecki to write for string quartet. Three years later, the reclusive Polish composer offered Kronos Quasi una Fantasia, one of his finest works, permeated with Polish liturgical chant and fired by folk music.

Throughout the '80s, Kronos continued to find one way after another to expand the reach of the string quartet into the broader world of music. It played arrangements of the music of Thelonius Monk and Bill Evans in jazz clubs. It approached composers, like the experimental downtown improviser John Zorn, who had little to do with the classical realm of the string quartet. It performed in film soundtracks, Philip Glass using it in his score to Mishima, David Byrne inviting it to play on the score for his film, True Stories.

Signing with Nonesuch Records in 1986, Kronos experimented with the thematic approach of the best pop-music recordings, creating aural sound portraits, such as Winter Was Hard, wherein sensually spiritual Arvo Pärt coexists with abstract Webern, provocative Zorn, lounge-lizard John Lurie, new-tango Piazzolla, somber Schnittke, and sentimental Barber. Also like a pop record, there are no notes, leaving the music to speak for itself. The Quartet-or classical music's Fab Four, as Rolling Stone called it-took yet another cue from pop music in its presentation of live concerts. It developed a sophisticated sound-enhancement system, special lighting, and, of course, the Kronos look, which, like a typical pop band, sported new outfits and hairdos annually.

But perhaps the most radical aspect of Kronos's career has been in its sheer sociability, the idea of taking the string quartet so far out of chamber music's chambers that the players are comfortable collaborating with musicians from around the world. Dawn Upshaw has sung a Bollywood tune with Kronos. Lee Hyla made a setting of Allen Ginsberg's Howl for the poet to recite with Kronos. Around the globe, Kronos has performed with gypsy band Taraf de Haïdouks, Mexican rockers Café Tacuba, Chinese pipa player Wu Man, Gambian kora player Foday Musa Suso, Nubian tar player Hamza el Din, throat singers of Tuva, Lebanese nay virtuoso Ali Jihad Racy, and Indian tabla player Zakir Hussain. It is a rare Kronos concert these days that doesn't have at least one guest, either live or on tape.

In the late 1990s, some of the Kronos members went through a series of personal setbacks and tragedies, and the Quartet rallied by generating yet more important music. Riley wrote one of his most inspired works, the spiritually expansive 40-minute quartet, Requiem for Adam, in commemoration of Harrington's son, who had died suddenly at age 16. Jeanrenaud left Kronos for health reasons, and in 1999 Bay area cellist Jennifer Culp joined the ensemble without missing a beat.

Now, at the beginning of a new century, Kronos's world seems, if anything, larger than ever. Having successfully inspired African composers to write for string quartet and having branched out to Silk Road countries, Kronos has approached Mexican music with typical relish. Nuevo ranges from the lecherous bachelor pad music of the 1960s to Tijuana's hottest dance music to art music. One original score, Osvaldo Golijov's K'in Sventa Ch'ul Me'tik Kwadulupe (Festival for the Holy Mother Guadalupe), is a soundscape in which a field recording of a ritual is overlaid with yearning, sensual writing for the string quartet and marimba that is part our world, part that of the Indians of Chiapas, but with the distinctions blurred. Like the rest of Nuevo, it represents something new in cultural osmosis. After 30 years of experience, Kronos has transcended the need to translate or explain one culture or genre to another. It has bypassed appropriation to reach the point of an immediate sharing of pleasures and passions.

Ever since he presented that first bag of doughnuts in exchange for music, Harrington has demonstrated an undiminished ambition to reinvent the string quartet, in general, and to achieve unprecedented popularity for Kronos, in particular. Twenty years ago, when Kronos enjoyed its first flush of fame, Harrington told me that his dream was that one day Kronos might play in large arenas as an opening act for, say, the Rolling Stones. That hasn't happened, and it would hardly make sense anymore. The Stones are too busy keeping alive the past. Kronos, meanwhile, moves on.

Today, Harrington, older and wiser but if anything more optimistic, refuses to have anything to do with the fashionable fretting about the future of classical music. Last summer, he said that he considers our age to be the most exciting he has ever known for music, what with so much activity in all parts of the globe. For him, the story of Kronos is not the innovations of the past 30 years, but what is yet to come. Sun Rings, which will tour over the next year or two, has all the makings of a sensation, a vast musical evocation of the cosmos that is one of Riley's grandest scores. It also contains a visual presentation of planetary imagery created by Willie Williams, the designer of nothing less than the Rolling Stones' current tour.

Kronos has not forgotten its roots, of course. This year it will include Crumb's Black Angels in concert, but made fresh with a new theatrical element. And in its latest commissioning scheme, Kronos happily recalls the '60s adage to never trust anyone over 30. The ensemble has instigated a call for scores from composers younger than it is. Whatever it takes, Kronos keeps the musical floodgates open-and open wide.

Mark Swed is the music critic for the Los Angeles Times. He is currently at work on a biography of John Cage.