RM50 biasing issue

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ricky

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Any of you had this issue? I was biasing my EL34's and I set one at say, 35 and go to the second one. I set it for 35 and then re-checked the first one and it had gone down to 22. I re-set it for 35 and then the second one will have jumped up to something like 47 and on and on. Am I missing something here?
 
you have to swap a resistor or two.

http://mtsforum.grailtone.com/viewtopic.php?t=15264&highlight=bias+problem
 
It sounds like your EL34'S are not a matched pair. Are they new?

Swap their positions and if you get the same bias differences then it's the tubes.
 
Thanks both of you. I tried crunchbunch's recommendation and that seemed to be the issue. When I switched places on the tubes, I got almost the same differences. They were matched at one point but no longer I guess. This is much easier than paying someone to put in a new resistor.
 
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