The German conductor, organist, harpsichordist, composer, and musicologist, Diethard Hellmann, , was a son of a teacher and a Kantor, and was grown up in the tradition of Saxonian church music. He was a member of the Thomanerchor Leipzig. He studied church music in Leipzig with Günther Ramin.
When he was 20 years old, after the conclusion of his studies, Diethard Hellmann began his first position as Kantor and organist of the Thomanerchor Leipzig. He was the organist for early recordings of Bach cantatas by Günther Ramin. Hellmann was Kantor at the Friedenskirche in Leipzig from 1948 to 1955. At the same time, he was a teacher for organ at the Musikhochschule Leipzig, director of the choir of the Hochschule since 1952, and until 1951, a teacher at the Fürstenschule in Grimma. In 1950, he won a prize for organ at the first International Bach Competition. He started teaching choral conducting in 1952 and was appointed vice director of the department for church music in 1954.
In 1955 Diethard Hellmann changed the centre of his activity and moved to Mainz as Kantor and organist of the Christuskirche in Mainz, where he founded and conducted the Kantorei, which in 1965, was named the Bach-Chor Mainz. In November 1955, he performed a concert of Bach cantatas. In 1958, he was awarded a prize by German broadcaster Südwestfunk (SWF) for his composition Musik auf Christi Himmelfahrt (Music for Ascension). In 1962 he launched the International Bach Festival of Mainz. Hellmann was a teacher for Protestant church music at the Peter Cornelius conservatory of Mainz, and from 1963, he was Professor at the Johannes Gutenberg-Universität Mainz as well.
Diethard Hellmann took the Bach-Chor Mainz on concert tours to France, Poland and Israel. In 1972 he apopeared with the Bach-Chor Mainz at the Original Abu-Gosh Music Festival, performing George Frideric Handelís oratorio Israel in Egypt (1st Performance in Israel). He collaborated with singers such as Theo Altmeyer, Wolfgang Anheisser, Aldo Baldin, Ria Bollen, Ursula Buckel, Margrit Conrad, Eva Csapò, Herrat Eicker, Dieter Ellenbeck, Kurt Equiluz, Olaf Erksen, Brigitte Fassbaender, Gerhard Faulstich, Nobuko Gamo-Yamamoto, Agnes Giebel, Marie-Luise Gilles, Hedy Graf, Ernst Haefliger, Julia Hamari, Andrea Hellmann, Egon Hoss, Kurt Huber, Philippe Huttenlocher, Georg Jelden, Helena Jungwirth, Roderic Keating, Martha Kessler, Adalbert Kraus, Helmut Krebs, Roland Kunz, Horst Laubenthal, Hildegard Laurich, Siegfried Lorenz, Halina Łukomska, Karl Markus, Barbara Martig-Tüller, Friedrich Melzer, Klaus Mertens, Carl-Heinz Müller, Siegmund Nimsgern, Hartmut Ochs, Hans-Joachim Rotzsch, Ernst Gerold Schramm, Peter Schreier, Verena Schweizer, Dieter Slembeck, Jakob Stämpfli, Ortrun Wenkel, Annelies Westen, Kurt Widmer, Edith Wiens, Horst Wilhelm and Lotte Wolf-Matthäus. They recorded more than 100 Bach Cantatas, broadcast by SWF once a week. 8 CDís from those radio recordings were released in the late 1990ís by DdM-Records (Dokumente der Musik, Mitterteich). Hellmann conducted also Jean Gillesí Requiem, J. Haydn's Harmoniemesse, Camille Saint-Saënsí Oratorio de Noël, L.v. Beethoven's Missa Solemnis, Max Regerís four Choralkantaten of, and Frank Martin's Golgotha.
In 1974, Diethard Hellmann was appointed Professor at the Musikhochschule München, where he was the Director (President) from 1981 to 1988. Among his students were Gabriel Dessauer and Pierre Even. Hellmann died in 1999 in Deisenhofen. In a memorial service in the Christuskirche, the Bach-Chor Mainz performed J.S. Bach's Es erhub sich ein Streit, BWV 19, because Hellmann had loved the tenor aria Bleibt, ihr Engel, bleibt bei mir! (Stay, ye angels, stay with me).
Diethard Hellmann composed organ music. He published sheet music, including reconstructions of J.S. Bach's Ärgre dich, o Seele, nicht, BWV 186a for the 3rd Sunday in Advent, Singet dem Herrn ein neues Lied, BWV 190a and the Markus-Passion (BWV 247). His reconstruction of Markus-Passion (BWV 247) has been recorded by several conductors (see: BWV 247 Markus Passion - Recordings).
Selected recordings: Bach / Pergolesi: Psalm 51 BWV 1083 (Kurrende 1966); Camille Saint-Saëns: Oratorio de Noël (recorded by SWF in 1976); Bruckner: motets, Zoltán Kodály: Laudes organi, Hedwig Bilgram, organ (1979); W.A. Mozart: Vesperae de Dominica (1980); Max Reger: Choralkantaten (1980, later CD); Chorales and Choruses from J.S. Bach's Christmas Oratorio BWV 248 (1980); Haydn: Harmoniemesse (LP 1981); J.S. Bach: St Mark Passion BWV 247 (1983).