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Post by mitch8686 on Jul 24, 2009 14:45:39 GMT -7
Does anyone have any current bias specs for the Galaxie, including wall voltage differences, etc? I'm trying to bias my gal with a set of GT 6l6 GE's (#6) and a RCA nos 5u4gb and I'm getting some puzzling numbers here. At 424v on the plates, I'm showing 27ma. According to the bias charts I've read that's less than 50% plate dissipation. Also my wall voltage is right around 123vac. Am I missing something? Also, when I raise the plate current, the corresponding voltage drops and vice versa. What am I doing wrong guys? Any suggestions? It sounds good, but I just want to have a good basline that's within spec.
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Post by amakitalo on Jul 26, 2009 9:19:30 GMT -7
My numbers are a bit different, but I went through the same thought process. I get around 380 v on the plates but I just went with the charts and biased mine at around 45 mA. In my case that's around 60% and the amp sounds good. I consulted Myles before I biased the amp and he predicted that with modern 6L6 (30 w) tubes the bias would be in the high 30's. In my case that would have been less than 50%, so I went higher.
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Post by mitch8686 on Jul 26, 2009 14:27:29 GMT -7
Hmmmm, interesting. Well, right now it sounds good. The tubes are running kind of cool, then, so they'll last longer. That'll work with me. I might mess with it and go a little higher. I don't know. The confusing part for me is that the numbers don't make any sense when I reference them to a chart. Maybe I should email the Doc directly and see what he says.... Thanks for the response!!
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