Twenty-two Novembers ago, the Los Angeles Philharmonic started its then revolutionary, now widely imitated New Music Group. The idea was simple: Members of the orchestra would volunteer to participate in programs of current music. The concerts were first held, charmingly, in the Mark Taper Forum on whatever set happened to be up.

No one knew how well the notion of traditional symphonic musicians keeping musically up-to-date would catch on. It caught on. Musicians and concertgoers lined up to be included.

Outgrowing the Taper, the ensemble moved to the Japan America Theatre, where one attraction was the late-night neighborhood sushi bars and inexpensive noodle joints for audiences to hang out in after the concerts. For no reason whatsoever, the four or five Monday evening concerts a year were called the Green Umbrella series. When the Colburn School opened its excellent 400-seat Zipper Hall, the series relocated there and even sold out a couple of times, although everyone missed Little Tokyo and the cheap parking.

Now Green Umbrella has come under a larger silver umbrella, the Walt Disney Concert Hall. Monday night, Disney was nearly full and, despite an unusually austere and modest program, Green Umbrella began its 23rd season with an audience roughly six times its normal size. It featured six of the orchestra's principal players, each performing a solo work, no piece lasting more than 11 minutes and no piece older than the New Music Group itself. Two were world premieres commissioned for the program.

This concert was, as is everything for a while, a test of Disney's acoustics and versatility. Each musician stood or sat at the position on stage where he or she normally does when the full orchestra plays. With violin, cello, bass, clarinet, bassoon and piano, there was a wide, if not comprehensive, range of color.

Three of the solo scores have proven staying power. Steve Reich's "New York Counterpoint" features amplified solo clarinet playing against 10 prerecorded clarinet and bass clarinet parts. The pulsing instruments at the opening were a new sound in music in 1985, and the jazzy give-and-take among this many clarinets has retained its freshness. Lorin Levee is an excitable musician, and he played this exciting music with flair. A miked player was not, however, a good test subject for Disney, which isn't out of hot water yet with its muddy amplification system.

While "New York Counterpoint" obsessively multiplies clarinet sounds, Thomas Adès' "Darknesse Visible" for piano and Esa-Pekka Salonen's "Laughing Unlearnt" for violin are essays in subtraction. In his 1992 score, Adès removed notes from an early 17th century John Dowland lute song, creating mysterious trilling textures out of what was left. Joanne Pearce Martin played forthrightly Monday, her percussive tone clear and ringing in Disney's engagingly transparent acoustic.

"Laughing Unlearnt" is a fancifully virtuosic set of variations on a chord progression. Thinking about regaining laughter after Sept. 11, Salonen found inspiration in a line from Schoenberg's "Pierrot Lunaire," and Cho-Liang Lin gave the work a cheerful and spectacular premiere in La Jolla last year. Philharmonic concertmaster Martin Chalifour's beautiful and deeply moving playing was more muted, the laughing still somewhat unlearnt.

The two new pieces were for instruments with low ranges — bassoon and bass. Colin Matthews' "Bassoonova" has small melodic and rhythmic ideas that lurch forward with amusing insistence. Lee Hyla's "Detour Ahead" is just the opposite. Lovely, engaging, sometimes jazz-tinged gestures are rich and sumptuous but too quickly run out of developmental steam. Bassoonist David Breidenthal and bassist Dennis Trembly have colorful personalities and now the acoustic environment in which they can be appreciated.

Peter Stumpf played the U.S. premiere of Dutch composer Van Der Aa's "Oog" (Eye) for cello and prerecorded electronic sounds. Though a conventional study in new music aggression, it perked up the ear as the program's opening work.

Afterward, looking for some place to hang, part of the regular new music crowd hit the tiny bar at the exclusive new Patina restaurant downstairs. The bartenders did not seem pleased.