On January 20, 1965, the Byrds entered Columbia Studios in Hollywood to record "Mr. Tambourine Man" for release as their debut single on Columbia.   Since the band had not yet completely gelled musically, McGuinn was the only Byrd to play on "Mr. Tambourine Man" and its Gene Clark-penned B-side , " I Knew I'd Want You ".  Rather than using band members, producer Terry Melcher hired a collection of top session musicians , retroactively known as the Wrecking Crew , including Hal Blaine (drums), Larry Knechtel (bass), Jerry Cole (guitar), and Leon Russell (electric piano), who (along with McGuinn on guitar) provided the instrumental backing track over which McGuinn, Crosby and Clark sang.   By the time the sessions for their debut album began in March 1965, Melcher was satisfied that the band was competent enough to record its own musical backing.  However, the use of outside musicians on the Byrds' debut single has given rise to the persistent misconception that all of the playing on their debut album was done by session musicians.