OK New issue with JJ tubes!

[Chuck H]

I can't say if any thing has changed with EH in the last decade, but about ten years ago I used two pair each 6L6's and 6V6's in four different amps. Purchased from ??? They were great. Big power and no microphonics. I'm still in touch with one of the amp owners and those EH 6V6's are still in there (though he doesn't use the amp much). I would have gone right to EH for my recent EL34 search, but I was after the classic pentode sound and the EH is a beam tetrode.

[bob p]

Chuck, you're saying that EH is selling a beam tetrode as an "EL34"? What's up with that?

[big_teee]

The Data Sheet calls it a Power Pentode.
http://svetlana.com/pdf/electro-harmonix/el34eh.pdf
T

[Chuck H]

Well... When I first searched all I found was a tube marketed as an EL34/6CA7. My experience has been that such tubes are usually the 6CA7 type and NOT EL34's at all. But searching now I see that EH makes an EL34 and a 6CA7. Once upon a time it wasn't uncommon at all to see tubes actually marked on the glass as EL34/6CA7. In which case you knew it was a beam tetrode marketed as an EL34. So I missed that one. But look forward to trying them out some time.

[big_teee]

Well... When I first searched all I found was a tube marketed as an EL34/6CA7. My experience has been that such tubes are usually the 6CA7 type and NOT EL34's at all. But searching now I see that EH makes an EL34 and a 6CA7. Once upon a time it wasn't uncommon at all to see tubes actually marked on the glass as EL34/6CA7. In which case you knew it was a beam tetrode marketed as an EL34. So I missed that one. But look forward to trying them out some time.

I have a pair of the EL34EHs that are a couple of years old.
They are very tough and take abuse.
But, In my 2204 Amp, I always thought them to be thin sounding.
I like the sound of the JJ E34L, and the KT77s in this amp.
But, The survival rate has been poor, but I have High plate and screen voltage in this amp.
Always wanted to try the new issue Tung-Sol EL34B and the Mullard EL34?
T

[km6xz]

I have been getting EH 6L6, EL34 and 6550's lately and must admit, after never liking them in the past, these are strong. Have not had one fail since switching about 6 months ago. 12AX7's is another sadder story however with poor results out of the box. Unequal gain, low gain or dead are the most common symptoms. I have to talk customers into the selected Chinese which have consistently been quiet and balanced in gain. And 1/3th the price of wholesale EH 12AX7s.
Can't deal with JJ power tubes, horrible survival rates. I can't warranty my work for 90 if someone insists on them. A lot of people ask for them specifically so I suggest getting them on their own and I can check them, bias, burn them in, etc, but take no responsibility.
There is a well made brand here, Yerasov, that uses JJ stock and most of that brand I see are brand new units, right out of the box with shorted EL34s or 6L6's and popped HT fuse. Stick a Wing C or EH in them and they last forever. Apparently the JJs suffer from shipping damage. I do not get units shipped in like in my old shop where we got them from everywhere including Japan and Africa, shipped UPS. A collector in Hong Kong sent everything, even SVT's all the way to California. At that time were using Ruby Tubes exclusively.

[bob p]

I like the sound of the JJ E34L, and the KT77s in this amp.
But, The survival rate has been poor, but I have High plate and screen voltage in this amp.

How high? What topology are you using? What kind of screen dissipation?

Survival has been poor with high plate and screen voltages? That sounds odd, as the old EL34 are supposed to thrive at high plate voltages, and as I understand it, the E34L and KT77 were supposed to be designed to enhance EL34 reliability in high voltage applications, no?

I'm asking becuase I'm interested in a high reliability "skinny" tube for a 530V application where 6x6L6 might have trouble. Would be interested in hearing more about what survives vs. what doesn't.

[big_teee]

How high? What topology are you using? What kind of screen dissipation?

Survival has been poor with high plate and screen voltages? That sounds odd, as the old EL34 are supposed to thrive at high plate voltages, and as I understand it, the E34L and KT77 were supposed to be designed to enhance EL34 reliability in high voltage applications, no?

I'm asking becuase I'm interested in a high reliability "skinny" tube for a 530V application where 6x6L6 might have trouble. Would be interested in hearing more about what survives vs. what doesn't.

I was strictly talking about what seems to be high for the JJs.
The New Sensor tubes have held up fine.
My 2204 runs 525v on standby, and 500v in play mode.
My House AC runs 125-127V.
I used the stock marshall type 345-0-345 PT.
In my new build I will be using a 325-0-325 PT.
That should work out better, for my new application.
T

[bob p]

in other words, pentode topology, not distributed load?

[Bruce / Mission Amps]

I have been getting EH 6L6, EL34 and 6550's lately and must admit, after never liking them in the past, these are strong. Have not had one fail since switching about 6 months ago. 12AX7's is another sadder story however with poor results out of the box. Unequal gain, low gain or dead are the most common symptoms. I have to talk customers into the selected Chinese which have consistently been quiet and balanced in gain. And 1/3th the price of wholesale EH 12AX7s.
Can't deal with JJ power tubes, horrible survival rates. I can't warranty my work for 90 if someone insists on them. A lot of people ask for them specifically so I suggest getting them on their own and I can check them, bias, burn them in, etc, but take no responsibility.
There is a well made brand here, Yerasov, that uses JJ stock and most of that brand I see are brand new units, right out of the box with shorted EL34s or 6L6's and popped HT fuse. Stick a Wing C or EH in them and they last forever. Apparently the JJs suffer from shipping damage. I do not get units shipped in like in my old shop where we got them from everywhere including Japan and Africa, shipped UPS. A collector in Hong Kong sent everything, even SVT's all the way to California. At that time were using Ruby Tubes exclusively.

Where are you getting the Chinese 12AX7s from?
I used to buy good Chinese 7025s from Tom at Magic Parts. I still have a small handful and I think they were called Silver Specials 7025str.
I liked those a lot... as well or better then NOS and most triodes in the envelopes were very, very well matched.
I finally sucked it up and bought a whole 100 piece tray for something like $700.00....

I don't think those 7025STRs are around anymore but it proved to me beyond a shadow of doubt that the Chinese can build an excellent tube if they want to.

[wizard333]

I'd be curious on a wholesale source of those to. I can't seem to find ANYONE that makes a good reliable 12AX7 anymore. When they are good, they are good, but a lot of the time they aren't and I can't put up with the inconsistency and having people get pissed off because a new tube failed in under a month.

[Chuck H]

I deal with that all the freakin' time!!! I don't think the culling of Russian 12ax7 tubes by vendors is evident at all in any purchases I've made. Shuguang has been a tad better. I still need to cull bad tubes, but there are fewer and the price is much better. And they sound just fine. Good spectrum and gain. So... Lower price, fewer culls and of the good tubes the tone is very acceptable. For the very best tone in a new production tube I'd go with the Sovtek 12ax7lps. But they're so microphonic that there is no possibility of using them as the first tube in a high gain guitar amp. For that I use Shuguang tubes. I've tried the Sovtek WA and WC tubes but they lack gain. spectrum and just generally don't sound inspiring at all. The Chinese preamp tubes don't lack for tone and are slightly more consistent than the Rusky tubes. It's worth noting that the Shuguang preamp tubes have been the major amp makers standard for two decades!!!

[km6xz]

I buy directly from Shuguang 2,000 at a time. At that quantity, which is quite modest, they will brand them for me. My first batches were smaller so I bought unmarked bulk and silk-screened them. The dealing with the Chinese companies is MUCH easier than others because they want to sell things, not get in the way. I have turned over my tube importing, grading and sales to two young Russian woman who have the time and energy to grow it. One is a EE and the other is an economist. I have been using the brand name "Брощн Медведь" which is Brown Bear in Russian but suggest we change it to their names with sketch images of the two girls and label the tubes by common girl names.
I have had good luck with Chinese power tubes but they, generally, do not tolerate as much abuse. Running them in a sane amp and they work well and last fine. For ruggedness, I like the NOS Soviet era tubes which are tough, non-microphonic, cheap, and meet specs but some people think they do not sound as good as some types when stressed.

For my take on it, a good guitarist, with any tube will trump any tone fanatic who spends more time fretting over "tone" than practicing. The better a guitarist is, the less they are focused on amps or subjective sonic characteristics, real or imagined, of a bunch of wires, carbon and silicon. My perspective was from coming to music from the production end where I never worked with garage bands or non-pros until I retired decades later and started a repair shop. That later contact with amateurs and their search for "tone" as if a characteristic independent of playing style, song and technique, lead me to think, was primarily an amateur activity.
Good amps for accomplished expressive guitarists are those that do not get in the way and which do not have a strong signature characteristics. The signature sound, for those people have always come from signature playing and interaction of fingers and brain with a song that mattered. That has been my experience and why I never was tempted to start playing guitar after being around so many who were really good and realizing no matter how much effort and practice, I would only be a hack. So I focused on things they could not do. Worked for me.

One of my first guitar amp repair customers in the new repair service, which focused on pro studio field service, was a kid who just bought a complex effects collection of rack processors. He had his receipts and wanted warranty repair(when first opening the shop, I was doing the warranty for a large music store that had all the warranty authorizations but no repair shop, Bananas at Large in San Rafael Ca) on all this gear because it did not work right. I questioned him about what symptoms it had and asked which of the rack effects was the problem unit. He handed me a tape and said it was supposed to sound like the tape and none of it did. The tape was Jimi Hendrix. I was about to find out that those sorts of expectations and reliance on equipment was the norm for beginners. This separation of tone, song and skill set was something new to me, I never ran into that before. But I was a quicker learner in dealing with beginning musicians and wannabe recording engineers, both of whom were sure equipment was the only thing holding them back.

[km6xz]

Chuck, culling by Russian vendors is culling between different products from the same production line, with the same staff and same materials, just different shapes and sizes and label. There is only one source for all those brands of Russian tubes. The differences come from marketing rather than technical considerations. They are not going to go to the expense of sourcing different plate or heater materials if they all being sold to the same captive audience. There are two different anode material surface treatments but no other material differences, just size and shape. Same assembly jigs, same production line workers, same test and qc department.... Different ink color, box and logo and of course price.

[Chuck H]

I have to wonder then... Why does it work so well and consistently for certain power tubes and so poorly for preamp tubes I adore the Sovtek el84's I've used for the last decade. Consistent, rugged and good sounding. I would expect the same from the EH brand (since they're probably the same. basically). And I'll keep buying them for as long as they continue to work. Never had a bad tube in this designation. But the preamp tubes are, uh, Russian roulette (if you'll excuse the pun).

FWIW I sure appreciate having someone on the forum so close to this part of the matter. Invaluable information.