New production field coil speakers

[Phototone]

Originally Posted by electroking

The AM-2 amplifier they describe uses:

2 x 300B rectifiers, 300B output tube.

Interesting tube that works both as an amplifier and rectifier...

That 300B is a Western Electric (design) triode power tube. Designed for audio output. Almost any audio output tube "could" be used as a rectifier. It was Western Electric design practice to use same tube as audio output and also as rectifier.