Old JBL's

[EVBoy]

I've never seen these before. Noaf.

http://www.ebay.com/itm/VERY-RARE-1...pt=Vintage_Electronics_R2&hash=item2a1be398c7

 

[vintageboy]

it survived the war

 

[hjames]

Instead of a permanent magnet on the back of the cone, Field Coil speakers had an electro-magnet, which required a standalone power supply to energize.
Ebay is the right place for that - its a collector thing, but there are some audiophile companies looking to make new field coil drivers.