The Mastering Lab was a mastering studio established on December 27, 1967 by audio engineer brothers Doug Sax and Sherwood Sax, together with musician and composer Lincoln Mayorga, in Hollywood, California. This facility officially closed on April 11, 2008 and relocated to Ojai, California.
The Mastering Lab used three different lathes to cut records. The original Scully lathe is indicated in runouts by the letters TML. When a second Scully was added in 1972, the original became TML-M and the new one TML-S, with the M and S meaning master and slave. A Neumann lathe was added later and is indicated by the letters TML-X.
In June 2015 the studio ceased its activities after Doug Sax passed away, on April 2. The facility is now owned by Acoustic Sounds. As a result of the sale, The Mastering Lab relocated from Ojai, California to Acoustic Sounds headquarters in Salina, Kansas.

Engineers known to have worked here:
Mike Reese
Gavin Lurssen
Robert Hadley
George Jones (11)
Arnie Acosta
Ron Hitchcock
Sangwook Nam or Sunny Nam (2005-2012)
Tom Pessagno
Teresa Bustillo
Eric Boulanger (2)
Jett Galindo
Lois Walker
Alan Yoshida
Ron Lewter

Known to have mastered for:
ABC Records
United Artists Records
A&M Records
Warner Bros. Records
20th Century Records
Arista
Also listed as:
· Mastering Labs
· The Mastering Lab Ojai, Kalifornien USA