Tube Amp Output Questions ?

[ka7niq]

I have a small tube amplifier from China. It is 6 wpc Single Ended Class A with both 4 and 8 ohm taps for the speakers. The Taps are not marked 4 or 8 ohms and the company that sold it to me is out of business, and in China!
Is there any way to tell what Tap is the 4 ohm, and what Tap is for 8 ohms ?
I do not have a schematic of this amplifier, and doubt I can get one.

 

[baudouin0]

Measure between secondary taps. The 8R will have higher DC resistance although it could be <1R. If not just plug it in and choice the loudest.

 

[rayma]

Can you tell which secondary lead is ground?
Is there feedback from the secondary?

 

[kodabmx]

You didn't post a picture but usually they put the posts in order. 0 - 4 - 8 vs 0 - 8 - 4 with the "0" being the black connector / ground.

Another way to test is to play a signal and measure the voltage - the 8R output will be higher than the 4R output.