The German short-lived quartet Häx Cel from Hannover, formed by Dieter Neumann (fl, voc), Achim Neubauer (keyb), Michael Moebus (b) and Rainer Greffrath (dr), had existed only between the end of 1971 and the autumn of 1972. During this time they released a single and one LP on the tiny Dizzy Records, run by the jazz drummer Dietmar Siebrasse. It was he who was so impressed after one of their performances that he wanted to record a disc with them. The single was released in spring 1972 and a live performance at the Beethovensaal in Hanover was recorded at the end of October, which was then released as an LP in the same year. Their music was a fusion of classical works by Bach, Händel, Vivaldi and Beethoven, among others, with elements of progressive rock.

Their only album Zwai is one of the rarest German progressive LPs and highly sought after by Krautrock collectors.