Early Years and Career
Mueller studied at the Musisches Gymnasium, Frankfurt-am-Main. At 19, the imposing, six-foot-seven Mueller made his debut as music director of Stuttgart Radio. He also founded and conducted a vocal ensemble there.
Career in Canada
Mueller moved to Montreal in 1951. He worked as a rehearsal pianist and later as a conductor for CBC Radio and TV, in particular for the programs CBC Wednesday Night and L'Heure du concert. He took lessons with Igor Markevitch in Mexico. In 1958, he won second prize in the Pan-American competition for conducting. His next appointment was as chorus master for the opera class of the Conservatoire de musique du Québec (CMM).
Mueller was the founding director of the Victoria School of Music. He served in that capacity from 1963 to 1965. He also became the conductor of the Victoria Symphony Orchestra in 1963. He spent part of that same year in Moscow as a guest professor at the Tchaikovsky Conservatory, where Maxim Shostakovich and Rudolph Barshai were among his pupils. In 1965, he conducted the CBC TV production of The Barber of Seville. It won an Emmy Award for best foreign production.
During his years in Canada, Mueller conducted the premieres of several Canadian works, including Pyknon (Montreal Symphony Orchestra, 1966) and Diallèle (CBC Radio Orchestra, 1968) by André Prévost, the Symphony-Concerto (Toronto Symphony Orchestra, 1968) by S.C. Eckhardt-Gramatté and the Symphony No. 2 (Edmonton Symphony Orchestra, 1977) by Malcolm Forsyth. During the summer of 1978, he conducted the second session of the Orchestre des jeunes du Québec (OJQ) at the JMC Orford Art Centre.
Career in the United States
In 1967, Mueller left the Victoria Symphony Orchestra and settled in the United States. In 1968 and 1970, he conducted in Moscow, Leningrad and Riga. He appeared as a guest conductor in many Canadian and US cities. He also taught conducting at the University of Wisconsin–Madison, the Yale School of Music, the Juilliard School and the Curtis Institute of Music.
Following Mueller’s death in 2016, New York Philharmonic music director Alan Gilbert, a former pupil, said that Mueller “was kind of an institution, and he made an enormous impact, not only on me but on a whole generation of conductors trained at Curtis, Juilliard, and Yale. Certainly, he came to occupy the preeminent position in the world of conducting teaching in the US.”