Revolver (Beatles album) group collective since 1962, and gave them an unprecedented amount of time to prepare for a new album. Writing in "The Beatles Forever", Nicholas Schaffner cites 1966 as the start of the band's "'psychedelic' period" and adds: "That adjective implies not only the influence of certain mind-altering chemicals, but also the freewheeling spectrum of wide-ranging colors that their new music seemed to evoke." Music journalist Carol Clerk describes "Revolver" as having been "decisively informed by acid", following John Lennon and George Harrison's continued experimentation with the drug LSD since the spring of 1965.<ref name="Clerk/Uncut"> Available at Rock's Backpages (subscription required).</ref>
Revolver (Beatles album) resulted from varying tape speed (or varispeeding) extended to recording a basic track at a faster tempo than they intended the song to sound on disc. During the sessions, Emerick recorded McCartney's bass guitar amplifier via a loudspeaker, which Townsend had reconfigured to serve as a microphone, in order to give the bass more prominence than on previous Beatles releases. Although this particular technique was used only on the two songs selected for the May 1966 single, an enhanced bass sound was a feature of much of the album. Emerick also ensured a greater presence for Starr's bass drum, by