"organ drone" albums Irrlicht (1972), and Cyborg (1973). Tangerine Dream 's ambient drone album Zeit (1972), and to a lesser degree Phaedra (1974). Fripp and Eno : the 21-minute drone ambient of "The Heavenly Music Corporation" on No Pussyfooting (1973), the 28-minute drone ambient of "An Index of Metals" on Evening