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Raising the Bias

Hi,

When adjusting the bias on my 300B tubes (amplifier recommendation 85MA) I noticed I could not raise the bias beyond 45 to 50 MA. The manual adjustment knob in the amp was turned to the highest point. Previously the tubes could eaisly be raised to 90MA range. Does this mean the tubes are bad or have got weaker? Am I close to a tube burning out?

Thanks.
dilly

Showing 1 response by dilly

dilly OP
113 posts
 
Mcintech, Thanks for the reponse.

I did try another pair & was able to raise the bias to 85MA, so the problem is not with the amps.

I actully like the sound on the older pair but will this be hazardous to the amps in anyway?
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