4 Senior L.A. Philharmonic Musicians to Leave Orchestra : Music: Principal concertmaster Sidney Weiss is resigning today. Cellist Nino Rosso, violist Irving Manning and trombonist Ralph Sauer are leaving at the end of the season.

At least four senior members of the Los Angeles Philharmonic will be leaving the orchestra by the end of this season. Among them is principal concertmaster Sidney Weiss, who has held the first chair position with the orchestra since 1979.

Violinist Weiss, 65, said his resignation is effective today. He said he planned to notify his colleagues Sunday, at the time of his final concert with them at the Dorothy Chandler Pavilion.

“I resigned from the orchestra for personal reasons,” Weiss said Friday. When asked if his departure was amicable, he replied, “Of course.”

Ernest Fleischmann, the orchestra’s executive vice president and managing director called Weiss “a man of tremendous integrity and a superb violinist. I think he earned the respect of musicians, conductors and soloists as well as his section. They respect him as much for his violin playing as for his human qualities.”

An orchestra’s principal concertmaster is responsible for setting the tone of the first violin section, serves as liaison between the conductor and the strings and plays orchestral solos.

Alexander Treger, the orchestra’s 45-year-old concertmaster, will assume Weiss’ duties for now, Fleischmann said. Treger will also lead the orchestra on its tour of Europe this summer. “There’s no problem in having Alex lead the orchestra,” Fleischmann said. “He’s done it often enough. It doesn’t create a problem.”

Treger will not automatically become principal concertmaster, however. Fleischmann said music director Esa-Pekka Salonen “will doubtless meet with the relevant committees of the orchestra and a search will begin.”

Assistant principal cellist Nino Rosso and violist Irving Manning both plan to retire in September, at the end of this season. Both men joined the orchestra in 1956, two years before Salonen was born.

Manning, 78, said he had been thinking about his retirement for a year now and hopes to do more chamber music work. Rosso said he also plans to pursue chamber music, as well as teaching.

Ralph Sauer, one of the orchestra’s two principal trombone players, said he is also leaving the orchestra at the end of the season “to pursue other interests.” Sauer, 49, joined the orchestra in 1974.

Asked if Salonen is making personnel changes, Fleischmann sidestepped the question, saying that “a music director has continually to do whatever is best for the orchestra. He’s responsible for the personnel and has to see the personnel is used in the best way.”

Weiss has worked for several of the nation’s best orchestras. After 10 years under conductor George Szell at the Cleveland Orchestra, he left in the mid-1960s to play for Zubin Mehta in Los Angeles. He was here less than a year before heading to Chicago to become co-concertmaster at the Chicago Symphony.

Chicago born and raised, Weiss remained with the Chicago Symphony from 1967 to 1972. He then left for Europe to pursue a solo career as well as recitals with his wife, pianist Jeanne Weiss, with whom he has long performed as the Weiss Duo. He became concertmaster of the Orchestre National de l’Opera de Monte Carlo (now the Monte Carlo Philharmonic) in 1973, and was there six years before returning to Los Angeles.

Weiss became concertmaster of the Los Angeles Philharmonic in October, 1979, replacing Sidney Harth. The invitation came from Carlo Maria Giulini, with whom he’d worked during his tenure in Chicago.

Looking ahead, Weiss said he and Jeanne Weiss, his wife of 40 years, intend to do “a great deal more playing” as the Weiss Duo. “The most important thing to me in the world is playing the violin well and doing justice to music. That is what I have always tried to do and what I will continue to try to do.

“I’ve been very fortunate to work with violinists of such high caliber. It’s been for me a great, great privilege to work with them. Their ability as individual players and as a collective ensemble is exceptional.”