[BC] Old Speaker

[Dale H. Cook]

At 12:42 PM 11/25/2005, Glen Kippel wrote:

>I don't have any specific info, but you need to check to see whether or 
>not the speaker has a permanent magnet.  A lot of old speakers used a 
>field coil instead; typically it served double-duty as a filter choke for 
>the power supply.

Glen -

As Stanley said, the 540A is a cone speaker. Cone speakers:

http://members.cox.net/dalehcook/radios/pages/speaker.shtml#e2

and their earlier cousins, the horn speakers:

http://members.cox.net/dalehcook/radios/pages/speaker.shtml#l

predate the electrodynamic (field coil) speakers, and were used with 
battery sets:

http://members.cox.net/dalehcook/radios/pages/table.shtml#20
http://members.cox.net/dalehcook/radios/pages/table.shtml#620

Some of the earliest line-powered sets:

http://members.cox.net/dalehcook/radios/pages/table.shtml#17

used horns, cones or early permanent-magnet speakers such as the RCA 100-A:

http://members.cox.net/dalehcook/radios/pages/speaker.shtml#100a

but when sets with more powerful output tubes such as the 45 were introduced:

http://members.cox.net/dalehcook/radios/pages/console.shtml#89

the electrodynamic (field coil) speaker was used in order to handle the 
higher output powers.

Dale H. Cook, Chief Engineer, Centennial Broadcasting, Roanoke/Lynchburg, 
VA - WZZI / WZZU / WLNI / WLEQ
http://members.cox.net/dalehcook/starcity.shtml