Although sometimes billed as a bass baritone, Franz Crass was a high bass with an instrument of unusual warmth and suppleness. In an age in which most German basses offered weighty, droning sounds, Crass' very beautiful instrument ideally fit such roles as Sarastro (he sang the Sprecher in Die Zauberflöte as well), Rocco in Fidelio, and the Hermit in Der Freischütz. Not until the arrival of Kurt Moll was there a European bass quite so mellifluous. After his first few recordings, especially those with Otto Klemperer, Crass was invited to take on many engagements, both in the studio and on-stage. After studies at Cologne's Hochschule für Musik, where he worked extensively with professor Clemens Glettenberg, Crass took several first place awards offered by academies and broadcasting organizations. In 1954, he was offered a contract by the Städischen Bühnen Krefeld/München-Gladbach and remained there for two years before joining Hanover's Landestheater. In 1959, he began a long association with the Bayreuth Festival, performing in Lohengrin and returning in Der fliegende Holländer the following year. In later years, he appeared there in several operas recorded for commercial release. Unfortunately, some of his colleagues in Parsifal and Lohengrin were in poor voice and Boulez's conducting of the former was superficially fast. From 1962 to 1964, Crass performed with the Cologne Opera, moving thereafter to the Hamburg State Opera. As his career expanded, he was a frequent guest in Munich, Vienna, at La Scala, and at Covent Garden. Visits to America were fewer and the singer's one production at the Chicago Lyric Opera (Fidelio) showed the effects of the deafness that eventually ended his career. Although his Rocco was still handsome in sound, persistent flatness of pitch proved worrisome. During his prime, Crass recorded many of his finest roles. At least two live performances of his Dutchman were preserved, matched in vocal splendor only by Hans Hotter's WWII-era document. Crass was the superb Sarastro in Karl Böhm's Zauberflöte that also featured the elegant Tamino of Fritz Wunderlich. Various recordings of Bach demonstrate how much better the composer's bass arias sound when sung by a full and genuinely beautiful voice.