Which outside producer worked with Metallica on The Black Album?

Bob Rock was the outside producer who worked with Metallica on The Black Album. Rock was already known for producing commercially successful hard-rock recordings, including Mötley Crüe’s Dr. Feelgood, and Metallica believed his approach could help them make a stronger record.

The collaboration changed the band’s studio methods. Rock encouraged the members to record more collaboratively rather than building parts in isolation. He also pushed for live-feeling performances, harmonic vocals from James Hetfield, and more attention to the clarity and impact of the songs.

The sessions were famously difficult. Metallica’s perfectionism led to many takes, repeated editing, and multiple remixes. Rock later described the process as stressful, and disagreements between the band and producer were documented in A Year and a Half in the Life of Metallica and the Classic Albums program about the record.

Rock remained associated with Metallica for many years. He also produced Load, Reload, Garage Inc., St. Anger, and other projects, but The Black Album was the recording that began the band’s long studio partnership with him.