Vaziri and Khaleqi may be considered leaders of the progressive branch of twentieth-century Persian music. With their strong Western orientation balanced by an equally strong sense of the value of traditional Persian culture, they changed the entire course of music and music education in Iran. A more conservative and less active group of musicians who contributed to the preserving rather than the modernizing of Persian music are the followers of Mirza· Abdullah, the master credited with the present version of the radif. At his death in 1917, Mirza Abdullah had had a large number of students to whom he had taught his radif. Several were inspired enough to undertake the formidable task of transcribing it. The two most successful were Mehdi Gholi Hedayat, who shares with Vaziri credit for the earliest Iranian attempts to use Western notation for Persian music, and Mussa Mac ruffi.The most influential teacher of Persian music during this period was Abol Hassan Saba (d. 1957). For many years he conducted private music lessons in his home and later taught in the Conservatory of National Music. While most of the present generation of performers were trained by Saba, their students study the radif from his printed instruction manuals. Also influential for the development of contemporary Persian music was Darvish Khan (d. 1926), inventor of the pish-daramad. As a performer, Darvish Khan participated in one of the landmarks of Persian music— the first European phonograph recordings. During the years between the granting of the Persian constitution (1906) and World War I, Darvish Khan and a number of other musicians made three trips to Europe to record Persian classical music for His Master's Voice (Source: Classic Persian Music).