Which recording studio in Los Angeles was the primary location for Metallica's The Black Album sessions?

One on One Recording Studios in Los Angeles was the primary location for Metallica's The Black Album sessions.

Metallica began recording there in October 1990. The band also worked for about a week at Little Mountain Sound Studios in Vancouver, British Columbia, while final overdubs and mixing later took place at A&M Studios in Hollywood.

The sessions lasted roughly eight months and were marked by demanding performances, repeated takes, and frequent arguments with producer Bob Rock. Rock wanted the band to record more collaboratively and encouraged a stronger live feeling, rather than having the musicians build the tracks in isolation.

The studio location can be confused with the other facilities listed in the album credits. One on One was the main recording site; Little Mountain Sound was used briefly, and A&M handled the final overdubs and mixing. Distinguishing those roles makes the answer precise.