The German underground band Tyll from Stuttgart was a project led by guitarist Teflon Fonfara, who was joined in 1973 by Günter Klinger, the former drummer of the band Eulenspygel. They performed live under the name Eulenspygel, but were forced to change the name following conflicts and a brief legal dispute. They subsequently adopted the name Tyll Eulenspygel but disbanded shortly thereafter. In early 1975, Fred Kersten, head of the small independent label Kerston Records (Gäa), offered Fonfara the opportunity to produce and release a German rock LP. He then formed a new studio band, consisting of members and friends of Tyll Eulenspygel, much like the story of the legendary band Mammut: an ad-hoc lineup was put together and given complete artistic freedom.

From 1 to 12 April 1975, the new band, named Tyll, recorded their first and only album at the TFE Studio in Neustadt an der Weinstraße. The members were Teflon Fonfara (g), Achim Bosch (b), Günter Klinger (dr), Michael Scherf (voc) and the backing singers Ulrike Schempp and Susanne Schempp. At the end of the month, their debut album Sexphonie was released – a provocative title deliberately chosen to attract more attention and boost sales, but which failed miserably. They played an interesting and varied style of psychedelic rock with experimental elements drawing on progressive rock, hard rock and folk. Alongside a number of instrumental tracks, the album features German vocals. This low-budget production with all the charm of a limited-run private pressing is a very rare and sought-after artefact of German rock history.