On 23 March, while American producer Phil Spector began mixing the "Get Back" tapes for release as the Beatles' "Let It Be" album in Abbey Road's Studio 4, McCartney completed work on his eponymous album in Studio 2. Although McCartney has frequently maintained that he was ignorant of Spector's involvement until receiving an acetate copy of "Let It Be" for approval, author Peter Doggett writes that after "several weeks", McCartney had finally "answered the string of messages he'd received about Phil Spector" and had agreed to let him prepare "Let It Be" for release.