Discs pressed by Monarch have "MR" within a circle stamped in the matrix runout 'dead wax' or the "MR" may be found etched. (Please refer to profile images for examples of each)
Many early 50's/60's pressed at Monarch lack the "MR" within a circle stamp, and only contain a standard Processing (Plating/Metalwork) 'delta' number △00000 which is common to many processing (plating/metalwork) plants and pressing facilities. Many early Monarch pressings that lack the "MR in a circle" dead wax stamp can still be identified based in the known association with the releasing Label AND the standard 'delta' number, but the existence of a △00000 type etching does not automatically mean Monarch by itself.
The Monarch pressing plant identity is also evidenced on Atlantic & ATCO recordings by an "MO" suffix to the matrices.
See ATCO Records for details of this (and other ATCO plant IDs).
Pressings on PolyGram labels from 1979-80 were identified on the label by a '24', and A&M releases pressed by Monarch had a 'C' displayed on the label.
Known to have pressed for;
-Dot Records, Chess, Duke, Carlton, A&M Records, Alston Records, Colpix Records, Buddah Records, Paramount Records
Monarch was founded in 1945 by Nate Rothstein and Nate DuRoff (sometimes spelled Du Roff or Duroff), the latter of whom remained with the company well into the late 1970's. Around 1948, the plant moved its operations to 4852-54 West Jefferson Boulevard which would be its home for the next three decades.
Pressing records mainly for independent labels from the 1950s to 1980s, but some major labels as well.
In March 1961, Monarch was purchased from Rothstein and DuRoff by Cosnat Record Distributing, parent company of Jay-Gee Record Corporation which owned Jubilee and Josie Records, though the two men would continue to operate the plant. (Cosnat changed its name to Jubilee Industries, Inc. effective 01 Aug 1966.)
In June 1970, Monarch and its parent, Jubilee Industries, were purchased by Viewlex, Inc; thereafter, Viewlex made Monarch a wholly-owned subsidiary, incorporating the plant into its other pressing operations including American Record Pressing Co., Allentown Record Co. Inc., and Sonic Recording Products, Inc.
Viewlex went bankrupt in 1976 and would be reorganized two years later as ElectroSound Group, Inc. Also in 1978, Monarch moved into a new pressing plant at 9545 San Fernando Road in Sun Valley. Around this time, the stamped 'MR' in a circle that had graced the deadwax of many a Monarch pressing since 1960 (backwards at first, then forwards) disappeared, replaced by a handwritten 'MR'. Within a few more years, Monarch ceased pressing 45's in styrene and switched to pressing entirely in vinyl.
After ElectroSound merged with a graphic productions firm, IGC Inc., in January 1985, the Monarch name was phased out and the plant officially renamed Electrosound Los Angeles.