Metallica hired Bob Rock for The Black Album after hearing his production on Mötley Crüe's Dr. Feelgood.
Rock's earlier work convinced the band that he could give their recordings a more forceful and polished sound. Metallica had been produced by Flemming Rasmussen on several earlier albums, but the group wanted a different approach for its fifth studio record.
Rock pushed the musicians to perform more collaboratively in the studio. He suggested recording tracks live, encouraged harmonic vocals for James Hetfield, and demanded repeated takes until the performances felt right. These choices contributed to the album's broad, powerful sound.
The collaboration was not easy. Rock and the band argued over lyrics, arrangements, and performance details, and the recording process lasted for months. Randy Staub was the engineer, Michael Kamen arranged orchestral parts on “Nothing Else Matters,” and George Marino mastered the album; none of them was the producer.