RCA normally gave their microphones a two digit model number, sometimes followed by a letter designating the first in a series or an updated model. In the case of this particular unit the company gave it a name rather than a number, the "Aeropressure".[aero-1] The "Aeropressure" was an omni-directional dynamic mike designed for sound systems, broadcast studio "talk back" and other general purpose uses.
The "Aeropressure" has a very "Art Deco" body design that certainly set it apart from other microphones of the era. This mike, as far as I can determine, came out in the late 30s or early 40s. I remember, in my youth back in the 1950s, seeing this mike used in PA systems of that time. The stylish RCA "umber gray" two-tone paint scheme!
RCA, in addition to broadcast equipment, built sound equipment for public address systems, school and industrial sound systems. The "Aeropressure" mike could be found in RCA's sound equipment catalogs of that era. The mike also appeared in RCA's broadcast equipment catalogs, as mentioned before, as a "talk back" mike used in the control rooms of radio station studios to give instructions verbally to performers in the studio. RCA said it could be used as an "emergency" announce microphone but obviously the "Aeropressure" did not have the wide range response of RCA's more expensive broadcast models.
The "Aeropressure" came in both high and low impedance models so it could be used with many different types of sound equipment. The unit had a "clevis" type swivel to adjust the position of the mike and used a 3/8 inch pipe thread stand attachment...but RCA included an adapter for attachment to the standard 5/8-27 thread of common mike stands.[Aero-3//4]
I think the "Aeropressure" name must have come from the very modern style of the body and the fact that it was a omni-directional or "pressure" type operating design. An additional feature with the mike was a "hat" that could be attached to the front of the mike to give a more directional effect to the higher frequencies.[Aero-2] Personally I thought this hat was rather silly looking and was not all that effective.
The "Aeropressure" sold new for probably less than 50.00...still a lot of money back in the day...but today on Ebay you can see this mike...sometimes in pretty bad condition...going for up to $300.00!
Here are some pictures of this very stylish microphone from America's premiere manufacturers...Radio Corporation of America...RCA. [Aero-1,2,3,4,5,6]