The Tube Thread

[oneblackened]

I don't have any inherent problem with JJs. Their tubes are usually well made and they don't fail often. As far as high voltages go, JJ takes the cake on not blowing up - well, JJ and Gold Lion. That's about it. Chinese stuff is sometimes good but it's really variable in quality (like most things Chinese), and data sheets are not commonly available for them. Russian stuff is often not good about high voltages (the big exceptions being the Tung-Sol 6L6GC-STR which handles high voltage situations better than most 6L6s, and the Gold Lion KTs) or cathode followers.

 

[Descent]

@oneblackened by high voltage you mean running the bias hot?

 

[mnemonic]

@oneblackened by high voltage you mean running the bias hot?

From what I remember, JJ EL84’s are quite robust and can handle high plate voltages better than others. I think their EL84’s and 6V6’s are quite well regarded.

Worth doing some googling. I seem to remember them being well liked on TGP.

 

[efiltsohg]

@oneblackened by high voltage you mean running the bias hot?

Nah,plate voltage is part of an amp's design regardless of biasing. Vintage Fenders are notorious for chewing up new production power tubes

 

[oneblackened]

@oneblackened by high voltage you mean running the bias hot?

Nope, I mean B+. Most of their tubes can actually take the voltages on the datasheets and then some. Their EL84s are pretty robust and can deal with Voxes fairly well (and Voxes are notorious for chewing through power tubes because of how rocket hot they run).

JJ 6V6s are a super robust 6V6 that can take +500V on the plates, which is WAY higher than vintage designs which were meant for a max of about 300-320V. Blackface Fenders are notorious for running these tubes way above spec - a Deluxe Reverb AB763 does ~420VDC on the plates, for example. The plates can usually take that in 6V6s... the screen grids, not so much. So for a tube like the JJ 6V6S, which has 6L6GC voltage ratings (500V Ua/450V Ug2) and an extra couple of watts plate dissipation over a 6V6GT (14w vs 12w), it's a perfect option.
JJ E34Ls are also particularly durable, and are one of the few tubes that won't consistently blow up in a Bogner Helios (which runs at above 500V B+ and screen), the others being KT77s (Rated at 800V Ua/600V Ug2), SED EL34s (800V Ua/510V Ug2) and the Ruby EL34BHT (rated for something like 800V Ua/550V Ug2).

 

[Descent]

@oneblackened Thanks for the info.

My buddy is a electronics engineer (a degreed one to boot) that does his own analog tube amp designs and other things. He's actually tested pretty much any preamp tube on the market. It was strange to get his opinion vs the common forum one on JJ.

I'll just wait and see.

 

[oneblackened]

@oneblackened Thanks for the info.

My buddy is a electronics engineer (a degreed one to boot) that does his own analog tube amp designs and other things. He's actually tested pretty much any preamp tube on the market. It was strange to get his opinion vs the common forum one on JJ.

I'll just wait and see.

His opinion on JJ is because their quality control from the factory is rather inconsistent, especially with power tubes. As long as you buy your tubes from a company that properly tests their tubes, you shouldn't have problems.

JJ's preamp tubes are (in most cases) the most consistent on the market.

 

[efiltsohg]

He could also dislike them because the different tone doesn't fit with his designs

 

[oneblackened]

He could also dislike them because the different tone doesn't fit with his designs

He's not the only tech I've heard that from, though.

 

[Konfyouzd]

We're already discussing JJ it seems...

I'm still a bit of a tube noob (very long time SS / modeler user)

Just got a JSX which I'm really liking. I bought it used and it came tubed with JJs.

I was told this thing needs a boost but it seems incredibly tight as is and I kind of like whatever sound the previous owner achieved with this amp.

I see the switch is set to EL34, but is there a way to identify the tubes so that I know which retube kit the previous owner used so I can keep this sound?

Do the high gain preamp tubes have a marking indicating they're high gain or otherwise?

(I have not fully opened it yet)

 

[oneblackened]

We're already discussing JJ it seems...

I'm still a bit of a tube noob (very long time SS / modeler user)

Just got a JSX which I'm really liking. I bought it used and it came tubed with JJs.

I was told this thing needs a boost but it seems incredibly tight as is and I kind of like whatever sound the previous owner achieved with this amp.

I see the switch is set to EL34, but is there a way to identify the tubes so that I know which retube kit the previous owner used so I can keep this sound?

Do the high gain preamp tubes have a marking indicating they're high gain or otherwise?

(I have not fully opened it yet)

The tubes will be labeled as to what they are. The high gain part, not so much.

 

[MetalHex]

Can i use a generic contact cleaner to clean my scratchy pots or does it have to be a good brand?

 

[vick1000]

Can i use a generic contact cleaner to clean my scratchy pots or does it have to be a good brand?

Deoxit 5 aresol is best due to removing oxidation, but generic will work ok.

 

[efiltsohg]

Are there any current production EL34s that are worth a damn? I'm eyeing a used Laney...

 

[vick1000]

Are there any current production EL34s that are worth a damn? I'm eyeing a used Laney...

http://www.dougstubes.com/ruby-el34-bht.html

http://www.dougstubes.com/power-tubes/el34-kt77-6ca7/jj-6ca7.html

 

[efiltsohg]

http://www.dougstubes.com/ruby-el34-bht.html

http://www.dougstubes.com/power-tubes/el34-kt77-6ca7/jj-6ca7.html

Is there any particular reason to use the Ruby EL34-BHT over the more popular Ruby EL34B-STR? How do the two compare?

Also, does anybody know if the Chinese Groove Tubes EL34-M is the same as the Ruby BSTR? Which as far as I can tell is the same as the Sino EL34-B?

 

[oneblackened]

Are there any current production EL34s that are worth a damn? I'm eyeing a used Laney...

I swear by Gold Lion KT77s in EL34 amps. They're expensive but they're super durable. If not that, then I would just spend the extra cash on the Mesa branded Winged Cs (STR-442). $200 for a quad is quite reasonable for Winged Cs and they're very durable indeed. It's too bad SED isn't making audio tubes any more.

Is there any particular reason to use the Ruby EL34-BHT over the more popular Ruby EL34B-STR? How do the two compare?

The BHT can handle considerably higher screen voltage (550V is the rating, iirc) but is otherwise similar to the BSTR. It's VERY hard to find datasheets for Chinese tubes, you sort of have to trust that they are what they say they are.

Also, does anybody know if the Chinese Groove Tubes EL34-M is the same as the Ruby BSTR? Which as far as I can tell is the same as the Sino EL34-B?

It's not. I have some EL34Ms in front of me, and it's a distinct design from the big bottle Chinese EL34s. The Shuguang (Sino) EL34B is the same tube as the BSTR, Ruby just tests theirs very strictly.

 

[oneblackened]

So... got an NOS or at least "tests NOS" Tesla E83CC. Should have my thoughts on it sometime today.

 

[oneblackened]

Okay, Tesla E83CC.

These tubes are fucking outstandingly good. Really surprised at how much of a difference it made. They look more or less like a JJ ECC83S, but share little in common other than that. They're bright but not edgy, they're super clear, and the low end is as solid and tight as can be. They're also dead quiet. If you can find one for a good price, get it! You can find tubes that "test NOS" or are NOS for $60-85 on eBay.

With that said, make sure you don't confuse it for a JJ - they're faked more often than almost anything else I've seen (Amperex is pretty common, too). There are some pretty obvious giveaways, if you know what to look for. JJs have copper grid posts, Teslas have a silvery material. JJs have one getter ring support, Teslas have two. JJs have thinner bases with more of the bead around the pins exposed, Teslas have thicker bases with less of the bead exposed. JJs usually have a rounded top, Teslas are always more squared off.

 

[efiltsohg]

It's not. I have some EL34Ms in front of me, and it's a distinct design from the big bottle Chinese EL34s. The Shuguang (Sino) EL34B is the same tube as the BSTR, Ruby just tests theirs very strictly.

Good to know. The Laney I just picked up came with a pair of (edit: pre-Fender) GT-EL34-Ms and they sound good, granted I haven't compared them to anything else yet.

The XXX came with GT-EL34-R which I'm guessing is EH. I might swap those for some JJ 6L6GC or KT77. Not really interested in spending $200 for gold lion KT77s