The RCA Type 44 microphone is a bi-directional ribbon microphone, or pressure-gradient microphone, first introduced by the

RCA Corporation RCA Corporation was a major American electronics company, which was founded in 1919 as the Radio Corporation of America. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Company ...

in 1931.

History

Dr.

Harry F. Olson Dr Harry Ferdinand Olson, E.E., Ph.D. (December 28, 1901 – April 1, 1982) was a prominent engineer and inventor with RCA Victor, the Acoustic Research Director of RCA#Diversification, RCA Laboratories, Princeton, and a pioneer in the field of 20 ...

began working for

RCA Laboratories RCA Corporation was a major American electronics company, which was founded in 1919 as the Radio Corporation of America. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Company ...

, where he developed ribbon microphones, first with field coils and then with permanent magnets, resulting in the first ribbon microphones with bi-directional pickup pattern, the RCA Photophone PB-17 and PB-31, introduced in 1931. The PB-31 was employed by

Radio City Music Hall Radio City Music Hall (also known as Radio City) is an entertainment venue and Theater (structure), theater at 1260 Sixth Avenue (Manhattan), Avenue of the Americas, within Rockefeller Center, in the Midtown Manhattan neighborhood of New York C ...

in 1932. Also in 1931, RCA introduced the Type 44-A Velocity Microphone. A smaller and lower-priced version of the uni-directional Type 77-A, the 44-A's smooth sound and defined pattern control reduced the effect of reverberation on soundstages and offered higher gain-before-feedback in live sound applications, making it a staple of the

audio recording Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording t ...

and

broadcasting Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...

industries. In 1940, RCA updated the Type 44 with improved magnet material to introduce the Type 44-B and Type 44-BX. The 44-B and BX were both a slightly larger version of the 44-A. The 44-BX has the ribbon mounted further towards the back giving it a smaller figure 8 pickup pattern on the rear side. The Type 44-B and BX remained in production until its discontinuation in 1957.The RCA 44 was discontinued in 1957. The RCA Type 44-BX and Type 77-A ribbon microphones were the most popular microphones for recording in the 1930s and 40s. They were popular not only in broadcasting studios, but also on film studio scoring stages, where they were often used to record string sections. Many of the top American scoring stages still use these ribbon microphones today.

Diaphragm

The diaphragm of the Type 44 and other early RCA ribbon microphones is a very thin (2.5

microns The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

) metal ribbon crimped with 19 pitch 90-degree perpendicular corrugations. This very lightweight ribbon is suspended under very little tension. As the ribbon vibrates, a voltage is induced at right angles to both the ribbon velocity and magnetic field direction and is picked off by contacts at the ends of the ribbon.

Legacy

Jon R. Sank joined RCA's acoustical laboratory in 1957, and designed the BK11, a successor to the Type 44. In 1976, RCA exited the ribbon microphone business. After RCA exited the ribbon microphone business, Wes Dooley and Bob Gerbracht founded Audio Engineering Associates, or AEA, first servicing vintage RCA microphones, then manufacturing replacement parts. In 1998, after recreating and fabricating all of the parts of the original RCA 44 microphone, AEA began manufacturing the R44C using RCA's original methods, including tools given to Dooley by Jon Sank at RCA. AEA continues to manufacture recreations of classic RCA designs, as well as new updated variations. In 2005, the RCA Type 44-A Velocity Microphone was inducted into the TECnology Hall of Fame.

References

{{Reflist Ribbon microphones