What was the name of the Los Angeles studio where Metallica recorded The Black Album?

Metallica recorded most of The Black Album at One on One Recording Studios in Los Angeles.

The album's recording sessions began there in October 1990 and continued for much of the following year. The studio is described in album documentation as being in the Los Angeles area, and it became the principal setting for the painstaking work that produced Metallica's new sound.

The band also spent about a week at Little Mountain Sound Studios in Vancouver, British Columbia. Additional overdubs and mixing took place at A&M Studios in Hollywood, so One on One was the main recording location rather than the only facility connected with the album.

This detail is sometimes confused with A&M Studios because the latter was used during the final stages. The finished record was mastered by George Marino, while Randy Staub handled engineering and Mike Tacci assisted with the engineering work.