In 1966 he obtained his doctorate in Basel under Arnold Schmitz with a dissertation on "The Organ Tablature of Clemens Hör".
In the following years, sponsored by the Swiss National Science Foundation, he spent time researching and compiling sources for a complete edition of the works of Arcangelo Corelli.
In the summer of 1972 he received his habilitation in musicology: in 1973 he became professor of European music history at the University of Hamburg where he remained until his retirement in 2001.
He is co-editor of the work editions of Corelli, Hasse and Handel, editor of the Göttinger Händel-Beiträge, which he founded in 1984, and of the six-volume Händel-Handbook (2008-2012).
He is also co-editor of various musicological series (among others Abhandlungen zur Musikgeschichte, Vandenhoeck & Ruprecht, Göttingen, Beiträge zur Geschichte der Kirchenmusik, Verlag Ferdinand Schöningh, Paderborn) and the Hamburger Mendelssohn-Vorträge, Verlag Christians, Hamburg.