please help troubleshooting vh4

[mansin_mind]

Ill get straight to the point here. I can bias my diezel correctly with a dmm when I put 6l6s. Once I'm done biasing it correctly with el34s and I turn it on to play I can hear a low frequency hum and behind it I can here the amp distortion but at a lower volume than the hum. Like I said all steps are done correctly to bias and I have no trouble with 6l6s. Any thoughts in what it might be?

 

[MARK2C]

Have you tired the bias switch in the 6L6 position with the EL34's ?

Most likely it's bad tubes, but may be the bias resistor for the EL34 position is faulty.

 

[mansin_mind]

Yes the switch is see to el34. Can you tell me which resisted would this be that you are talking about? Is it an easy fix? I do have basic soldering skills

 

[Peter Diezel]

You didn´t had the issue with the old tubes ?

 

[mansin_mind]

Hello Mr diezel. Thanks for the concern. This is the 2nd set of new Ruby el34s. At first I thought I had a bad quartet so I sent them back to the seller and he gladly exchanged them for another quartet. Still the same issue but when I put in a new 6l6s everything works well. Like I said, the switch is set to the el34 position, I connect the dmm correctly and I adjust the bias as recommended but I still get the same issue. Any clue?