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Post by cedarchoper58 on Feb 28, 2021 17:43:56 GMT -5
my current tubes have a 3.5ma differnce from one to the other is that ok.
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Post by Leftee on Feb 28, 2021 18:43:04 GMT -5
What amp? How does it sound?
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Post by cedarchoper58 on Feb 28, 2021 18:49:56 GMT -5
What amp? How does it sound? 67 Black Face pro reverb. has 2 6L6 tubes |
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Post by Leftee on Feb 28, 2021 18:52:33 GMT -5
If the amp sounds great and a tube (or tubes) aren’t red-plating, you’re golden. That’s the short answer. More math and information required for more/better info.
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Post by cedarchoper58 on Feb 28, 2021 19:10:47 GMT -5
If the amp sounds great and a tube (or tubes) aren’t red-plating, you’re golden. That’s the short answer. More math and information required for more/better info. it is biased at 36 and 32.5ma and is running 488V on the plates it does not red plate but has sounded better. Im using Tung Sol 6L6's. i generally like them to be within about 1.5 ma of each other but is that nessary and could the 32.5 ma tube be not sounding good. i thought about spitting it on 36ma like one at 38ma and the other at 34.5ma but dont want to blow it up i run it hard on 7 for hours with tube screamer cranking it at gigs |
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pdf64
Wholenote
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Post by pdf64 on Mar 1, 2021 3:15:34 GMT -5
Consider that the application here is a guitar amp which will be driven far past its limits of linearity, not something that requires high precision, eg a missile guidance system. Valve guitar amps and great guitar sounds have been around long before the concept of matched sets of output valves. Prior to the mid 80s, the balance of any valves purchased was complete pot luck, and to have a pair within 10% of each other was a sign that a lottery ticket purchase was in order  Hence I think you may be putting an undue importance and significance on what is a negligible discrepancy in idle anode / cathode current. As long as they’re not too far apart it’s not, per se, a cause for concern. As you’re working the amp quite hard, and you’ve noticed it’s not sounding its best, my thinking is the cause is probably not due to that slight discrepancy, more likely the valves are just wearing out a bit. I suggest swapping in a set of known good spare valves to see if that resolves the issue. If no joy, consider having a competent tech check it over. |
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DrKev
Wholenote
It's just a guitar, it's not rocket science.
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Post by DrKev on Mar 2, 2021 16:54:36 GMT -5
I don't think I have ever had tubes that didn't run differently. Even if initially matched, they'd drift before too long and 10%-12% difference was totally normal. As long as the hotter one of a pair isn't running too hot, all is fine.
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Post by Seldom Seen on Mar 2, 2021 18:15:29 GMT -5
^ I couldn’t agree more Dr. ^
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Mar 2, 2021 18:24:19 GMT -5
Yes, it’s only a problem when the discrepancy is significant, eg 50%, as the imbalance causes hum, early clipping.
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Post by rdr on Mar 30, 2021 11:48:01 GMT -5
And to think that I would go to Drug Fair for power tubes for my BF Super Reverb. And run it at high volume with an additional Bandmaster cab (what's impedance?). And I never had any problems and it sounded great!
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