[BC] Old Speaker

[Alan Alsobrook]

Speaking of old speakers, This is one I found in my shop, I'm not sure 
of the vintage but it's definitely not current production. Notice the 
adjustment on the top rear, anyone know what that's for?

http://sbe7.org/pics/SPA.JPG

Pictures go through F Just change the A to a B ect..

Dale H. Cook wrote:

> At 06:34 PM 11/25/2005, Jeff Johnson wrote:
> 
>> cone loudspeaker. There was a thin rod protruding from the apex of the 
>> cone which entered a magnetic assembly.
> 
> 
> The driver was essentially a 1920s telephone earpiece - pretty much the 
> same thing as found in a set of 1920s headphones. The cone speaker 
> mechanically coupled the movement of the driver diaphragm to a paper 
> cone to diffuse the sound, the horn speaker used the same sort of driver 
> to excite a column of air in the horn. Neither had very good frequency 
> response. The first speakers with decent frequency response were the 
> early RCA electromagnetic speakers - the 100-A (1927), 103 (1928) and 
> 100-B (1929), all of which sacrificed efficiency for better response by 
> incorporating a passive filter network. When driven by a '71A output 
> tube their sound was a great improvement over a cone or horn driven by 
> an '01A.
> 
> Dale H. Cook, Chief Engineer, Centennial Broadcasting, 
> Roanoke/Lynchburg, VA - WZZI / WZZU / WLNI / WLEQ
> http://members.cox.net/dalehcook/starcity.shtml
> 
> 
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-- 
Alan Alsobrook CSRE AMD CBNT
St. Augustine Fl. 32086 904-829-8885
aalso at Bellsouth.net