Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: passaloutre on September 08, 2023, 10:47:59 am
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Eurotubes offers a line of JJ power tubes they say are specifically made for them with twice the mica to allegedly "greatly reduce the possibility of "tube rattle" when used in combo amps." (source: https://www.eurotubes.com/store/pc/6L6GC-Double-Mica-Matched-Pair-59p2846.htm)
Has anyone tried these and found them to be an improvement over other tubes specifically with regards to rattle in combo amps? I have a couple combo amps that are prone to tube rattling, and I'm generally in favor of JJ tubes, so if there is an improvement, I'd be game to try.
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No experience with the JJ tubes, but some NOS 5751 tubes used double and triple micas to reduce microphonics. The old triple mica GE five star 5751 tube is a prime example. It is reasonable to me that additional micas would offer better resistance to rattles and/or microphonics in power tubes.
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Probably worth a try if your amp really has a problem with microphonics, especially since it is only $1 more expensive.
I'm a skeptic, however. Lot's o' snake oil being pedaled these days (as it always has been).
It takes much more to ruggedize a tube than an extra bit of mica. Ex: JAN 5751 have/had extra structure as well as additional of mica.
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Eurotubes offers a line of JJ power tubes they say are specifically made for them with twice the mica to allegedly "greatly reduce the possibility of "tube rattle" when used in combo amps."
So the other JJ tubes sold by Eurotubes are defective? :icon_biggrin:
I say that half-joking because rattling/microphonics is a defect in a tube, and your only real recourse is to buy from a vendor who will replace the rattling tube without a hassle. If the JJ tubes needed Eurotubes' special double-mica arrangement to reduce microphonics, then why does Eurotubes also sell the more-microphonic single-mica tubes?
- I'm not saying JJ tubes don't have microphonics!
- Actually the opposite: folks gripe about rattling power & rectifier tubes all the time; many offenders are JJ tubes.
When I see folks resorting to various dampener products (including those sold by Eurotubes (https://www.eurotubes.com/store/pc/viewCategories.asp?idCategory=8), I suppose for those rattly single-mica tubes), I can't help but perceive a band-aid on a defective product that should have been returned to the vendor. I think that's the only way to force factories to implement production-changes to fix the problem at the source.
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Eurotubes offers a line of JJ power tubes they say are specifically made for them with twice the mica to allegedly "greatly reduce the possibility of "tube rattle" when used in combo amps." (source: https://www.eurotubes.com/store/pc/6L6GC-Double-Mica-Matched-Pair-59p2846.htm)
Has anyone tried these and found them to be an improvement over other tubes specifically with regards to rattle in combo amps? I have a couple combo amps that are prone to tube rattling, and I'm generally in favor of JJ tubes, so if there is an improvement, I'd be game to try.
Call Eurotubes and talk to Eddie. A great dude with an engineering background who is hailed here in Portland by people way more knowledgable than me to be a guru. Just ask him and he can explain it to you. He’s toured the JJ factory and can talk on design and the manufacture of them.