Who was the primary producer of Metallica's The Black Album?

Bob Rock was the primary producer of Metallica's The Black Album.

Rock had already built a reputation for producing successful hard-rock records, and Metallica selected him to help reshape its studio sound. The band wanted a more forceful, live-feeling recording than the highly layered approach associated with some earlier work.

Recording with Rock was not always easy. The sessions involved disagreements over arrangements, performance, and the album's overall direction, but the collaboration produced a cleaner and more accessible sound without removing the band's heaviness.

James Hetfield and Lars Ulrich also received co-producer credit, which sometimes causes confusion about the answer. Flemming Rasmussen produced several earlier Metallica albums, including Ride the Lightning and Master of Puppets, but Bob Rock handled the main production of the 1991 album.