Revolver (Beatles album) as the Beatles'. While also highlighting the importance of the production, David Howard writes that "Revolver" was a "genre-transforming album", on which Martin and the Beatles had "obliterated recording studio conventions". Combined with the similarly "visionary" work of American producer Phil Spector, Howard continues, through "Revolver", the recording studio had become "its own instrument; record production had been elevated into art." Whereas "Sgt. Pepper" had long been identified as the Beatles' greatest album, since the 2000s "Revolver" has often surpassed it in lists of the group's best work. Sheffield cites the album's 1987 CD release, with the full complement of
1 (Beatles album) its original full-length version (slightly over seven minutes); on the American version of "20 Greatest Hits" it had been released as a shortened version. Before "1", all 27 songs were available mainly in two remastered CD versions. First on the respective Beatles albums released in 1987 (as well as "Past Masters, Volume One" and "Past Masters, Volume Two", released in 1988). The second remastering was made available on the CD versions for "1962–1966" and "1967–1970" (released in 1993). The songs on "1" were remastered specifically for the release in 2000. According to the liner notes of the album, the original