weber's orchestral career began at age 25, with a 1938 audition for arturo toscanini, who personally hired weber on the spot to play in the nbc symphony. weber played with the orchestra for two years as associate principal and e-flat clarinet, but was replaced just before the orchestra's 1940 tour of south america for a more experienced player. he instead went on to audition for erich leinsdorf, head of german repertoire at the metropolitan opera orchestra, who awarded him the principal clarinet position, which he held from 1940-1943.