Microphone Man-2


Page 2

Last time we featured the RCA 44 series of high fidelity ribbon microphones

RCA 74B inside showing the corrugated aluminum-foil ribbon between the magnetic pole pieces.

which were the “top of the line” in their day. Radio Corporation of America was in the business of making money…so the audio division decided to design a less expensive version of their very successful model 44 that would appeal to a wider segment of the audio industry.

Somewhere around the middle 1930s RCA came out with the model 74 ribbon mike (microphone) …it was nicknamed the “Junior Velocity” Velocity is another term used to describe a ribbon microphone. This refers to the way in which a ribbon mike picks up sound…by the velocity or speed of air particles pushed by sound waves toward the mike.

The Jr. Velocity was a junior in size compared to it’s big brother. It was about half the size as well as being much lighter weight. The model 74 did not have quite the extended frequency response…or fidelity of the model 44 series….but it still was a very good sounding mike. It also did not have the rubber shock absorber or forked mounting of the 44. It had a unique ball and socket type stand mounting that allowed the mike to be tilted up or down toward the sound being picked up.

RCA’s Model 74B came out somewhere in the late 30s and was very popular. It was manufactured until, I believe, about 1950. The first 74B’s had a shiny chrome windscreen with a black bottom and then in the 1940s RCA changed the wind screen to a brushed chrome and the color of the bottom part to what they called “umber gray”. Umber gray looked more like brown to most people! The change in color scheme was necessary for television as they didn’t want shiny parts becoming a “glint” in the camera’s eye.

The model 74B cost less than half of it’s big brother the model 44. This mike was very popular with smaller radio stations, but even many larger stations used them especially for announcing and for indoor remote broadcasts because of their small size and light weight. The 74 was very much used on PA systems, too, due to it’s lower cost. Even though the quality of sound did not quite match the model 44…the Junior ribbon still had the smooth, clean sound typical of a ribbon mike.

Radio stations in the local area that used the RCA Junior Velocity included KBEE, KFIV, Modesto Jr. College radio and KYOS. The McClatchy stations like KFBK, Sacramento and KMJ, Fresno also used the 74B.

Around 1950 RCA replaced the 74B with the KB2 “Bantam Velocity”. This mike was much smaller than any previous ribbon mike. The Bantam used much stronger magnet material that came out of WWII…this allowed the smaller size. The actual case of the mike was part of the pole piece of the ribbon magnet. Another name for the KB2 was “paint brush” because it had a built-in handle that made it look very much like a small paint brush. Inside the handle, under a cover piece, was an “XL” type connector. The “XL” connector was made by Cannon Electric Co. of Los Angeles which would later bring out the “XLR” connector that everyone knows today. RCA claimed that they commissioned Cannon to make the “XL” connector especially for the KB2 series of mikes.

In about 1954 RCA replaced the KB2 with the SK-46…this also was a relatively small size ribbon microphone that RCA continued to manufacture until they stopped making mikes. For more information on these mikes go to “www.coutant.org”,

RCA brought out one more bi-directional ribbon mike before they went out of the broadcast audio business. Actually this mike, the BK-11, was to replace the 44BX. It is about the same size as the Junior Velocity but with a more curved, modernistic shape, it also has a swivel mounting on the bottom. The BK-11 is an excellent quality mike like the 44BX. This mike is still seen once in a while on Ebay but I don’t think RCA sold as many of the BK-11 as compared to the model 44s and 74bs…which are seen all the time on Ebay. Until next time…this is Mr. Microphone signing off for now!









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