The bass work was done by Douglass Lubahn, who played on 3 of the Doors albums. One day, Clear Light's (his original band) producer, Paul Rothchild, asked Lubahn to work on sessions for The Doors' second album; as the group lacked a bass guitarist, uncredited session bassist Larry Knechtel had doubled Ray Manzarek's keyboard bass lines on select tracks for their debut album. In contrast to Knechtel, Lubahn played on seven of the ten tracks on Strange Days (1967) as a credited contributor. The Doors invited Lubahn to join the group as a full-time member during the Strange Days sessions, using Rothchild as a messenger; however, Lubahn declined the offer for multiple reasons, including his refusal to leave Clear Light. He also played on all but two tracks on Waiting For The Sun (1968) and, albeit less prolifically, on The Soft Parade (1969).