At which Los Angeles recording studio did Metallica mainly record The Black Album?

Metallica mainly recorded The Black Album at One on One Recording Studios in Los Angeles, California.

Recording began in October 1990 and continued through June 1991. The sessions were lengthy and demanding, reflecting producer Bob Rock’s effort to change how Metallica worked in the studio and to capture a more cohesive band performance.

The album was also recorded for about a week at Little Mountain Sound Studios in Vancouver, British Columbia. That additional location is why One on One is best described as the main studio rather than the only studio used.

One on One Recording Studios was located in North Hollywood, an area within Los Angeles associated with major recording facilities. The album’s extensive studio work contributed to its unusually polished sound compared with Metallica’s earlier releases.