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Thread: odd rca product

  1. #1
    Senior Member tomt's Avatar
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    Senior Member hatrack71's Avatar
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    What do you find odd about them? They look like old Racon and Western Electric drivers.
    4333As, Valencias

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    Senior Member 1audiohack's Avatar
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    Hi tomt;

    Are they yours?
    If we knew what the hell we were doing, we wouldn't call it research would we.

  4. #4
    Senior Member tomt's Avatar
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    Quote Originally Posted by hatrack71 View Post
    What do you find odd about them? They look like old Racon and Western Electric drivers.

    the fact they look like racon or western electric (or lansing) drivers instead of rca's ...





    Quote Originally Posted by 1audiohack View Post
    Hi tomt;

    Are they yours?

    no

    i wouldn't sell them if they were .


    ~~~~~~~~~~~~~~~~~~~~~~~~~~`````

    i suppose 'general' sarnoff didn't care who made whatever,

    as long as he and rca got the credit ...









  5. #5
    Senior Member Steve Schell's Avatar
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    These drivers are fascinating, at least for students of loudspeaker history (minutia?). I had intended to post about this auction; thank you tomt for starting the thread.

    The Lansing 284 compression driver was designed by the team that developed the Shearer Horn System for MGM studios. More can be read about this on our site here:

    http://www.audioheritage.org/html/pr...co/shearer.htm

    The first prototype and later production 284 drivers were built by Lansing Manufacturing Company. Lansing also made the woofers for the Shearer prototype systems, and began producing and marketing complete theatre speaker systems by late 1935. RCA had collaborated with the Shearer team on the system design, the most obvious contribution being Dr. Harry Olson's folded W bass bin. RCA began producing Shearer type systems in 1936, and used a number of components produced by Lansing Mfg. Co. in their systems, giving proper credit in their service literature. Although the RCA MI-1435 compression driver was described as "Lansing designed, RCA manufactured" in their literature, this driver looks so similar to the early Lansing 284 that I had always assumed that it was produced by Lansing for RCA. These drivers are scarce; this is only the third pair I have seen in the past dozen years of study.

    Perhaps some of the earliest 1435s were built by Lansing, it is hard to say at this point, but I am now convinced that these 1435s were built by RCA. There are many detail differences that lead to this conclusion. The diaphragms were pressed in a two part tool, where the Lansings were spun. The handles are different from the Lansings. The phasing plugs, though of the same functional design as the Lansing (and several decades of later Altec 288s) are built differently. The Lansings joined the concentric sections using square wire fit into milled channels and welded, where these RCA plugs appear to be assembled more like the later Altec drivers.

    In 1932 Edward Wente of Bell Telephone Laboratories had designed a 4" diaphragm, four concentric slit phasing plug compression driver for the Fletcher Horn System built experimentally at Bell Labs. Lansing's 284 was basically a reduced size version of Wente's driver with a 2.84" diaphragm and three slit phasing plug. When Western Electric decided to produce their Diphonic theatre speaker system that appeared to be heavily influenced by the Shearer Horn, they informed Lansing that his phasing plug design was in violation of Mr. Wente's patent. Lansing redesigned his driver to use a radial slit phasing plug, and it appears that RCA felt the heat as well. Shortly after, RCA introduced their new 1428 compression driver which used a radial slit phasing plug and Bakelite/silk cloth center-suspended cone shaped diaphragm.

    Anyway, for me this auction with its terrific photos of the RCA MI-1435 drivers goes a long way towards answering many lingering questions about this period in speaker history, the relationship between Lansing and RCA, etc.

  6. #6
    Senior Member Steve Schell's Avatar
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    More minutia... these drivers as well as the early Lansings feature holes drilled through the periphery of the rear cover. The early compression driver philosophy favored venting the rear of the diaphragm to the atmosphere, as evidenced by the Bell Labs patents on the 555 and 594 type drivers. Within a year or so the rear covers would be sealed IMO as the measurements didn't show any benefit and dirt was sealed out. Also, the field coil terminals on these 1435s were located precariously close to the handle, just as in the earliest Lansing Shearer prototype drivers, as the design had not yet evolved to the use of a locking motor plug on the side of the driver for field connections as seen in the later Lansing drivers.

    It looks as though Mr. Maxwell Graham, transducer engineer supreme at RCA in the 1930s, may have signed that tag on MI-1435 #1029. Greetings, sir!

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