Early Kraftwerk line-ups from 1970 to 1974 fluctuated, as Hütter and Schneider worked with around a half-dozen other musicians during the preparations for and the recording of three albums and sporadic live appearances, including guitarist Michael Rother and drummer Klaus Dinger, who left to form Neu!. The only constant figure in these line-ups was Schneider, whose main instrument at the time was the flute; at times he also played the violin and guitar, all processed through a varied array of electronic devices. Hütter, who left the band for eight months to focus on completing his university studies, played synthesizer and keyboards (including Farfisa organ and electric piano).