Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: uki on February 04, 2025, 10:16:51 am
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Hey guys !
6av6 tubes
I got this amp where V1 and V2 plates, are running little bellow the data sheet specification, between 80-90v,
it says 100-250v for for the plate voltage, should these voltages be above 100v ?
If so where in the circuit to change, plate resistors or power supply node?
Original thread: https://el34world.com/Forum/index.php?topic=31488.0
Thanks in advance!
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A few tens-of-volts difference won’t make much difference. But if you’re really worried about it, look at the power supply rail first. How worn out is the 6X4? Have you got another one you can plug in?
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'Datasheet spec' are just test conditions used at the factory, they're not a target for an actual circuit to aim at. Your numbers look spot-on if your B+ at point 'C' is around 200V, which seems plausible. Sounds to me like everything is working fine.
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A few tens-of-volts difference won’t make much difference. But if you’re really worried about it, look at the power supply rail first. How worn out is the 6X4? Have you got another one you can plug in?
The parts are really old from an old recorder, so hard to tell how much work it did before.
'Datasheet spec' are just test conditions used at the factory, they're not a target for an actual circuit to aim at. Your numbers look spot-on if your B+ at point 'C' is around 200V, which seems plausible. Sounds to me like everything is working fine.
Yeah node C is around 200V.
The amp is working fine and sounds good, 7w ish, my concern was if it was too low.
and i forgot to mention the original thread so here it is:
https://el34world.com/Forum/index.php?topic=31488.0
Thanks guys !!
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... How worn out is the 6X4?
The parts are really old from an old recorder, so hard to tell how much work it did before.
Yeah, it was more of a rhetorical question.
Although having said that, if you had another one to plug in, you might find it delivers higher B+, or not, tubes being ‘suck it and see’ things’n’all.