Robert Armbruster, 97, conductor, composer and concert pianist. A child prodigy, John Robert Sommers Armbruster began performing professionally at age 8 in his native Philadelphia. He moved to California as a young man and led the Robert Armbruster Orchestra for NBC radio, performing on such popular shows as the "Chase & Sanborn Hour." He later served for many years as head of recording film scores for MGM. Armbruster was a popular guest conductor at the Hollywood Bowl. On Monday in Santa Monica.