Bob Rock had Metallica record the 1991 album as a band playing together in the studio.
Earlier Metallica recordings often involved James Hetfield and Lars Ulrich constructing rhythm parts separately from Kirk Hammett and bassist Jason Newsted. For the self-titled album, Rock encouraged the musicians to perform collaboratively, aiming for a more natural live feel and stronger interaction between the players.
The change was part of a broader production overhaul. Rock wanted Hetfield to use more harmonic vocal parts and wanted the bass guitar to have a more audible role. He also challenged the band to simplify some arrangements after the long, highly intricate songs on ...And Justice for All. The resulting record retained Metallica’s heaviness while using clearer structures and more prominent low end.
The approach was demanding. The band reportedly recorded many takes, then selected and edited the strongest performances. The album was made primarily at One on One Recording Studios in Los Angeles, with additional work in Vancouver and Hollywood. Rock’s methods became central to the album’s distinctive sound.