If you have a tube that was arcing pretty much as soon as the amplifier warmed up, it appears that tube is bad right out of the box. Since you say the heater has an unusual appearance, this is more evidence that the fault lies with the new tube.
I assume your bias adjustments are OK (if you have any)... but try reversing the positions of these 2 new tubes, re-bias them (if you can), and IF the problem stays with the tube, it's bad - period. I assume they are guaranteed and if so, exchange it for a new one ASAP.
Hope that helps...
I assume your bias adjustments are OK (if you have any)... but try reversing the positions of these 2 new tubes, re-bias them (if you can), and IF the problem stays with the tube, it's bad - period. I assume they are guaranteed and if so, exchange it for a new one ASAP.
Hope that helps...
Re: Gold Lion EL84's
What are you saying - you've had arcing or "bright glowing" tubes? I'd be interested to know.
Just FWIW, I've had about 100 pieces pass through here with just 1 dud. It sounds like there may be another problem beside the tube in play here.
A word of warning - the "factory match" is horrible! I've had "factory matched" quads with 11 ma difference in plate current. And a poorly matched quad almost invariably has one or more "current hogs". These tubes will often red plate, etc., but it's not the tubes - it's the poor matching.
With 3 of four acting up I'd guess either you have a poorly matched quad or you have tubes that were severely shocked in transit.
MBMerlot said:
What are you saying - you've had arcing or "bright glowing" tubes? I'd be interested to know.
Just FWIW, I've had about 100 pieces pass through here with just 1 dud. It sounds like there may be another problem beside the tube in play here.
A word of warning - the "factory match" is horrible! I've had "factory matched" quads with 11 ma difference in plate current. And a poorly matched quad almost invariably has one or more "current hogs". These tubes will often red plate, etc., but it's not the tubes - it's the poor matching.
With 3 of four acting up I'd guess either you have a poorly matched quad or you have tubes that were severely shocked in transit.
Jim,
The ones that I have are in a Dr. Z Prescription Extra Strength Amp.
I'm experiencing the exact same physical symptoms as yours. From my experience. This occurs when the distance from cathode to plate is off alignment.
Probably going to call EH and tell them about it. Have you had 100 and only 1 out of that bunch did that to you? I would like to know, because I do plan on contacting them about it.
PS. Making tubes is an art form. They just haven't reached the pinnacle.
The ones that I have are in a Dr. Z Prescription Extra Strength Amp.
I'm experiencing the exact same physical symptoms as yours. From my experience. This occurs when the distance from cathode to plate is off alignment.
Probably going to call EH and tell them about it. Have you had 100 and only 1 out of that bunch did that to you? I would like to know, because I do plan on contacting them about it.
PS. Making tubes is an art form. They just haven't reached the pinnacle.
It may well have been the tubes - but according to what I can find the bias on the amp is not adjustable. Is it cathode biased?
Were you able to confirm the bias was in the normal & typical 30 ma. area? Forgive me if I seem to be cross-examining you, I don't mean for it to sound that way. But just because a set of JJ or Mullard worked fine does not narrow it down to the Genalex tubes themselves when they were acting up. If the bias is not adjustable and is not cathode bias, a set of "hot" Genalex could act just the way you described and not be defective. They could have been just passing too much current and the screens and/or plates overheated. Sets of relatively cool JJs or Mullards wouldn't necessarily act up the same way.
I've seen that exact scenario many times on many different amps.
If you have any comments please share them, and thanks again!
Were you able to confirm the bias was in the normal & typical 30 ma. area? Forgive me if I seem to be cross-examining you, I don't mean for it to sound that way. But just because a set of JJ or Mullard worked fine does not narrow it down to the Genalex tubes themselves when they were acting up. If the bias is not adjustable and is not cathode bias, a set of "hot" Genalex could act just the way you described and not be defective. They could have been just passing too much current and the screens and/or plates overheated. Sets of relatively cool JJs or Mullards wouldn't necessarily act up the same way.
I've seen that exact scenario many times on many different amps.
If you have any comments please share them, and thanks again!
bleugh.....
got my replacement tubes..... and one is exhibiting the indredibly bright heater again. instead of the normal orange glow its really whitish yellow in the section you can see through the hole in the plate.
its not arced as yet.....
the quality control on these seems really bad. for instance, one of the tubes as about 2mm of heater filament exposed at the top. The other has barely anything, not great on tolerance control.
I hold out little hope for the replacement tube with the hotspot on the heater.
volatge measures a perfect 6.3v ac.
got my replacement tubes..... and one is exhibiting the indredibly bright heater again. instead of the normal orange glow its really whitish yellow in the section you can see through the hole in the plate.
its not arced as yet.....
the quality control on these seems really bad. for instance, one of the tubes as about 2mm of heater filament exposed at the top. The other has barely anything, not great on tolerance control.
I hold out little hope for the replacement tube with the hotspot on the heater.
volatge measures a perfect 6.3v ac.
OMG..... i really hope this is a mistake on behalf of the supplier.
whenever i send anything back component or toolwise i alway put a black spot on it with a sharpie marker. mainly because i have a bit of a trust issue.
Pulled the valve with the bright spot in it..... and there is my black spot. All this after i was promised they were replaced. grrrrr
I hope to god its a mistake, otherwise name and shame is coming.
whenever i send anything back component or toolwise i alway put a black spot on it with a sharpie marker. mainly because i have a bit of a trust issue.
Pulled the valve with the bright spot in it..... and there is my black spot. All this after i was promised they were replaced. grrrrr
I hope to god its a mistake, otherwise name and shame is coming.
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