RCA Aeropressure (MI-6206)

The Aerodynamic microphone appears in the RCA catalogue of 1945 as model MI-6206, in 1948 as MI-6206-G and in 1950 as the MI-6206-E. All three catalogues offer the 250 ohm version but none lists a high impedance option.

A post about the Aeropressure at Pro Sound Web claims that Aeropressure microphones were in production between 1945 and 1951. However, the May 1941 edition of Radio News tells carries the following news item which tells us that they were introduced in that year...

"RCA MANUFACTURING CO., CAMDEN, N. J., have announced a new microphone. This new aeropressure microphone is shown with the new "paracoustic" reflector baffle in place in such a way that the directional characteristics are sharpened, and feedback is reduced. When the baffle, held in place by the thumbscrew shown, is reversed, the opposite directional effect is obtained. Without the baffle, the microphone becomes a normal pressure microphone. The unit is ideal for all types of public address applications, as well as for amateur radio telephone transmitters."

Radio Today and Radio Craft magazines carried similar announcements in April and May of 1941. At that time a high impedance 40K Ohm model was available.

From Radio Service Dealer, 1946

"Because of its Styrol plastic diaphragm. the RCA Aeropressure Microphone is especially adaptable for work out of doors. The reversible paracoustic baffle permits either sharp or broad directional use for mobile interviews and pick-ups. Its frequency response is 60 to 10,000 cycles"

MoMics note:

Although the press releases claim a frequency range of 60 to 10 kHz, the RCA catalogs give a narrower 80 to 8 kHz response. This highlights the importance of defining the variance of output level within the reponse range.

From the RCA catalogue 1948

The MI-6206-G offers outstanding performance as a public address microphone. Its relatively wide frequency response, high sensitivity and attractive appearance also readily adapt it for use as a "talk-back" microphone in broadcast studios. It is well suited to the requirements of a program director's microphone or it may be used for emergency announce purposes.

Like other pressure operated microphones, the MI-6206-G is relatively non-directional at the lower frequencies and directional at the higher frequencies. The reversible paracoustic baffle supplied with this microphone will change the high frequency directional characteristics. This baffle either sharpens or broadens the directional characteristic, depending upon whether its concave surface faces toward or away from the microphone grille. This microphone is supplied with a clevis mounting bracket and a short six inch cable and female plug, or as indicated.

Features: Low cost; Good frequency response; Baffle for directional or non-directional application.

Specifications

Directional Characteristics: Non-directional (without baffle)

Output Impedance: 250 ohms

Effective Output Level: 56 dbm

Hum Pick-up Level: 109 dbm

Frequency Response: 80-8,000 Hz

Finish: Two tone umber gray

Mounting: ⅛" pipe thread (Supplied with adapter ⅛" to ⅝"-27 fixture thread. MI-12051 adapter required for ½" pipe thread.)

Dimensions: Length 5"; Diameter 2½"

Weight (unpacked) 2¼ Ibs.

About the RCA Aeropressure at the Coutant website

An Xaudia blog post with a timeline for many RCA microphones.

World Radio History has a large collection of RCA catalogues including those referenced on this page.