After the 1939 Klemperer left because of serious health problems. Four years later he was followed by Alfred Wallenstein. Wallenstein had been the principal cellist of the New York Philharmonic and had then been the youngest member of the Los Angeles Philharmonic when it was founded in 1919. Arturo Toscanini had encouraged him to become a conductor. He had conducted the LA Phil several times. During his years as conductor of the LAPhil Wallenstein recorded several concertos with famous soloists such as Jascha Heifetz.