[Guest]

Let me apologize in advance since this post has nothing to do with Philco radios or any vintage raadio.

I'm restoring a Gibson GA 6 F guitar amp with a Rolla field coil speaker. The speaker has the usual field coil winding and another winding that is connected in series with the speaker voice coil and secondary of the output transformer. Can someone tell me what the purpose of this winding is?

Any information would be greatly appreciated.

[Guest]

Sorry, the model number of the amp I'm working on is BR-6F .

[mandh]

Sounds like the "hum bucking" winding used on most radios of the 1930s. It was phased with the voice coil winding to remove any residual hum caused by the field winding.