Please provide details about the model DM53 made of DeMambro Sound Equipment Company of Boston, Massachusetts. Attached is a photo.
The DM 53 is an OEM variation of the Shure model 530: Model 530 User Guide
DM = Dynamic Microphone or DeMambro
53 = shortened version of 530
There was also the model DM57 - closely related to the model DM53. The DM57 was based on the Shure model 535.
Both DM models were from the 1950s/1960s.