Monarch Record Mfg. Co. Database
This site is dedicated to the documentation of all assigned "delta" numbers on every Monarch Record Mfg. Co. pressings. In my persuit to compile this data, I have scoured thrift stores, bargain bins, and online. This list is in no way complete and there may be errors. Corrections, submissions, and feedback are greatly appreciated.
A Brief History:
Monarch Record MFG. Co. was founded in 1945 by Nate Rothstein and Nate DuRoff where they started manufacturing 78's (shellac records). Around 1948 they moved to 4852-54 West Jefferson Boulevard in Los Angeles, California, where they began pressing 45's, mostly in polystyrene. Around 1955 they began pressing vinyl records and applied the same "delta" numbering system that another Los Angeles, and partner pressing plant, Alco Research & Engineering, was using. Early on, most Monarch pressings were Alco masters (using their metal work) and all known Alco delta numbers are listed here.
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. The plant finally closed in May 1986.
A special thanks to readers like Raymond D., Phillip A., Martin K., Jacob L., and Connie C. for adding some missing numbers. And also to Discogs from where I got the bulk of this information.