Tubes

[willib]

Three of these came out of a really old amplifier .

the speaker had an electro magnet.

not even a permenent magnet !!

i'm not up on my tubes but these are pretty old .

three have only 4 pins

[terry5732]

The speaker probably had an iron magnet that lost it's magnetism.

Check the filaments for continuity. The filament connections are the two thickest pins. Should be about 3/4 ohm. If open they are of no use. #45s are sought after if good.

[Jerry]

Hi Willib.

Well your on your way to building a singl ended or push pull "45" amp. These are open filliment triodes. A very common audio output tube of the late thirties early 40s.

They are still used today in very high end amps. I think the Chineez and Rusians are still making these?

You can get maybe 10 to 15 watts out of a pair.

                       JK TAS Jerry

[willib]

the speaker had what looked to be 1/2" thick steel  "U" shaped base , with about 4" dia. windings around it..

[willib]

The amp unit had at least five maybe six huge transformers on it .

it must have weighed 50 pounds easy.