O.C. MUSIC : Orchestra on Top of the World : The Orange County Youth Symphony has been to Europe and Asia. But this New York trip--to Carnegie Hall and the United Nations--is a special one.

Conductor John Koshak and the Orange County Youth Symphony are already veteran travelers. In 1983, they were the first American youth orchestra ever invited to play at the Bad Neuenahr International Music Festival in Germany; from there, they went onto Italy and Switzerland. In 1987, they went to China, Japan and Hong Kong.

Still, a trip beginning today, to New York City, is something special. The group will be one of four orchestras--and the only one from California--playing Carnegie Hall and the United Nations as part of a concert series sponsored by MidAmerica Productions, a group that produces professional and educational concerts in this country and in Europe.

“Carnegie Hall is considered the top concert hall in the country,” Koshak noted last week. The members of the orchestra--the cream of the county’s high school-aged crop as determined through auditions--”are very excited about the privilege of playing in that venue. In fact, they can’t stand it. It’s my first time, too. I started to get excited about a week ago.” The orchestra will play music by Beethoven, Dvorak, Charles Ives and Leonard Bernstein, the same program it played Sunday at Chapman College in Orange, where it is based.

The orchestra will play Friday at the United Nations and Sunday at Carnegie Hall. While in the city, the members plan to squeeze in tours of Lincoln Center, the Metropolitan Museum of Art, St. Patrick’s Cathedral, Chinatown and other tourist attractions. They return on Monday.

The trip will cost about $1,400 per person; 85 are taking part (70 orchestra members, Koshak and four staff members, and 10 parents to serve as chaperons). Each person will pay $1,000; the remainder will come from the Friends of the Youth Orchestra (a parent support group), and MidAmerica itself, which is donating $8,500 contributed by an unidentified underwriter in New York.

Koshak said that MidAmerica first invited the group to New York about six years ago but that dates could not be worked out. “They were aware of our work and my work and had heard the orchestra before,” Koshak said. “The orchestra has a strong reputation.”

e orchestra, founded in 1970 by a group of music teachers from local high schools, was based at Fullerton College before it moved to Chapman in 1976. Koshak, 53, who teaches conducting at Chapman, has conducted it since 1974.

He said his goal, “besides finding things they are able to play well, is to give them a foundation in the standard literature and at the same time introduce them to American composers. Also, besides teaching them about music--we discuss the differences in the periods of music, in form--I want to get them all involved in the discipline of the arts, which carries over into the other parts of their lives.”

The orchestra gives three public concerts a year at Chapman and eight, sponsored by the Orange County Philharmonic Society, at the Performing Arts Center in Costa Mesa for area fifth-graders. It operates on an annual budget of “a little over” $20,000, which comes from Las Campanas, a local music support group founded in 1963; the County Department of Education; Chapman College, and the Philharmonic Society.

Most of the members are high school juniors; the average age is 17, although some are as young as 13 and some as old as 23. They come from more than 40 schools, from all over the county.

Most of them don’t go on to major in music in college or to pursue professional careers as musicians. But Koshak said that is typical of youth orchestras. “This year’s group (of 90) probably has about eight seniors going on,” he said. “But even if they’re not going to major in it, music is a major part of their lives.”

Koshak is worried about the future, however. Each year, for various reasons, the orchestra experiences a turnover in membership of about 35%, he said. “A lot our current members were still in school when we had music programs in the schools, and they enjoyed them. But with the cutbacks (in school funding), we don’t have the pool of musicians we used to have. In fact, the majority of new members are coming from foreign countries.”