Thoughts on Tung Sol reissue 12AX7 and reliability?

[km6xz]

Why bother trying to make a device that obviously is not a 12AX7 in design, assembly materials work in a circuit intended to use a 12AX7? All those mentioned models are from the same production line with the same assemblers. My own dismal "success" with finding normally functioning New Sensor 12AX7's tell me that the factory just does not know what a 12AX7 is or how to copy one. They sure do not look the same on a curve tracer.

[Leo_Gnardo]

Why bother trying to make a device that obviously is not a 12AX7 in design, assembly materials work in a circuit intended to use a 12AX7? All those mentioned models are from the same production line with the same assemblers. My own dismal "success" with finding normally functioning New Sensor 12AX7's tell me that the factory just does not know what a 12AX7 is or how to copy one. They sure do not look the same on a curve tracer.

Interesting comment Stan. Do the TS or other New Sensor AX's resemble anything when you look at the curves? My spider sense tells me 1) Gnu Sensor isn't interested in improving them because why should they when they sell so many and/or B) Factory engineers "could" improve it but again why bother - lazy lazy lazy. I have a strong feeling the tube could be improved but let's not hold our breath... FWIW I used to have the same problem with solid state "kwality kontrol" when I worked at Fairchild Semi - I wanted to improve things and they wanted to swat me upside the head. "The squeaky wheel - gets the bullet."

We put the "K" in Kwality.

[km6xz]

I doubt anyone is doing any research in tubes now, nor are there a surplus of people with the training or authority to change the core product since the market is not growing and no one is going to have major incentive to spend profits on R&D, when there is a strong incentive to not have long lasting tubes, or to use less common materials, or hire real engineers.
I have not seen any evidence that are are any qualified engineers in the few remaining manufacturers, and from a sales point of view, they are not likely to hire any. They know customers have irrational evaluation criteria, (not on things that can be designed in) such as "sweet" , "crunch", "authority", "warmth" or "brittle" or any of the casually used nonsense terms that describe something that is not inherent in the tubes, and improvements in reliability to people who are always searching for an elusive tone character by switching tubes often.

It is easy to see that the majority of new tube purchases are to replace perfectly functional tubes. The first resort, for most people, for home remedy of a malfunction or misadjusted amp before taking it to shop is to replace all the tubes. When people call about a problem to see how much it would cost, I ask them if they changed tubes and if so, bring the "bad" tubes with them because they just wastes more money on needless tube costs than a repair would have cost. By bringing them, at least I can tell an estimate of how much life to expect from the "bad" tubes. Besides a tube that has been working for several months is statistically more likely to continue working than any new tube. The most unreliable time for a current era tube is when it is first taken from the box.

Curve, smurves, take a random sample of 10 tubes and the curves are off enough to convince an observer that they are different tube types. I test a lot of tubes, primarily my Chinese bulk buys, and every time I buy directly from the factory in Saratov and find the chinese tubes are closer and quieter but the customers do not trust Chinese tubes, because they diss Chinese clothing which they all buy. They have two choices, Italian for $500 for a t-shirt or $5 for a Chinese t-shirt. Both sell well but to different customers. There is nothing in-between.
If they just want their amp repaired and are not caught up in the hoodie-voodie of magic tubes dust, and not specify which tubes to use, I always select Chinese 12AX7s and EH 6l6s or EL-34 because those combinations for me have been the most reliable. I can, won't, use JJ....too many re-dos. The best GZ-34 tube I have seen is made by Ruby, gets with 5-10% of the Mullard reference old pulls I have. I have never had one fail since they first went into production in the late 90s. I think that was because Tom, is not an engineer and was over-compensating on materials and precision due to not knowing for sure little could get by. I played with a lot of the prototypes as little changes were made over a period of many months until the design was locked. It was all based on the measured performance of a couple unused but meeting spec old Mullard tubes.
If a company really wanted to duplicate the specs and reliability of the RCA 12AX7, they could but it would take some time, careful measurements and repeated adjustments. I do not see the incentive or desire from the current producers.

[soundmasterg]

If a company really wanted to duplicate the specs and reliability of the RCA 12AX7, they could but it would take some time, careful measurements and repeated adjustments. I do not see the incentive or desire from the current producers.

If I was going to have someone duplicate one of the old 12AX7 types, the American ones were reliable but many of the European ECC83's were better sounding and just as reliable. Mullard, Amperex, and Telefunken come to mind.

Also, does Ruby actually make that GZ34 themselves or is it rebranded by them and made somewhere else?

Greg

[Leo_Gnardo]

One of the "problems" is our friend daz seems to have been "blessed" with extra sensitive hearing. Not knockin' ya daz, hardly. There are "super-tasters" too, who can't stand some foods & beverages. I know a couple of those. Super hearers too. Hard people to please BUT when they're happy, you really have somethin' special. Before success is found, a lot of frustration.

If a company really wanted to duplicate the specs and reliability of the RCA 12AX7, they could but it would take some time, careful measurements and repeated adjustments. I do not see the incentive or desire from the current producers.

Yes indeed & that's a shame. Somebody that manages to match or best the classics will have the (tube using) world by the tail.

There was a lot of hype a couple years ago about the revival of the Blackburn factory. Glowing reviews about the working samples (ECC83) that were furnished. By the time reviews got to press, the factory was out of business. Could have been some sort of scam, also could have been a good faith effort that floundered. Projected price of the tubes was astronomical but mostly aimed at the deep pocket Hi Fi crowd.

There's also tubes now marketed as Northern Electric. Anybody know about these? Also sky high prices. I'm not going there. I'm cynically thinking they're just paint on some ordinary tube but open to hearing about anything different. If they were all that and a bag of chips I think we'd have heard more about them by now.

The best GZ-34 tube I have seen is made by Ruby, gets with 5-10% of the Mullard reference old pulls I have. I have never had one fail since they first went into production in the late 90s. I think that was because Tom, is not an engineer and was over-compensating on materials and precision due to not knowing for sure little could get by. I played with a lot of the prototypes as little changes were made over a period of many months until the design was locked. It was all based on the measured performance of a couple unused but meeting spec old Mullard tubes.

You've mentioned this before and thanks for helping Tom at Ruby with their rectifier as well as test gear. I've been a customer of Magic/Ruby for nearly 30 years, and rarely disappointed. Overbuilt - that may be the answer. Would that other manufacturers follow a good example. Ruby's 5AR4C is the only one I stock. Had a good jaw wag with Tom @ 10 years ago and he said dealing with the Chinese was the old lion tamer circus act. Wave a raw steak at 'em with one hand while poking 'em with a wooden chair in the other hand. May not have used those exact words but that's what it boils down to.

[g1]

There's also tubes now marketed as Northern Electric. Anybody know about these? Also sky high prices. I'm not going there. I'm cynically thinking they're just paint on some ordinary tube but open to hearing about anything different. If they were all that and a bag of chips I think we'd have heard more about them by now.

Possibly rebranded Full Music tubes. Were discussed in this thread: http://music-electronics-forum.com/t28329/

[Leo_Gnardo]

Possibly rebranded Full Music tubes. Were discussed in this thread: http://music-electronics-forum.com/t28329/

Remember reading that thread, and just re read it. Not much in the way of conclusions. Gotta suspect the Northern's are just paint on some ordinary tube. Wondering if anyone's had a squint inside. It's easy to tell the Chinese and JJ, might be a bit less easy (for me anyway) to ID which variety of Russian it might be. And considering Stan's experience with those, hardly worth the effort except for curiosity's sake.

Some marketing schnook is making Canada look bad. And that ain't right.

FWIW when =c= had 12AX7's they were highly variable. Some of them made space ship noises, but the ones that sounded good, sounded great! Marshall put them in early 2000's amps, sometimes with a Marshall logo on. Huge flat plates, either shiny (nickel I guess) or flat grey. Oh well that's over, likely to never be seen again.

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If I had more money than sense I'd put the dream team together, Stan & Salvarsan (because of his chemistry knowledge), possible others here, and get a world class production line together. (Please nobody be insulted because I left you out. Hey it's just a day dream on a perfect summer day, what we're having here right now.)

Now I have to apply some sense because I need the money ... back to work!

[km6xz]

If I was going to have someone duplicate one of the old 12AX7 types, the American ones were reliable but many of the European ECC83's were better sounding and just as reliable. Mullard, Amperex, and Telefunken come to mind.

Also, does Ruby actually make that GZ34 themselves or is it rebranded by them and made somewhere else?

Greg

The various versions of 12AX7s all "sound" better than the others if put into a circuit that is optimized for their parameters. So some circuits might favor one style of tube over the others for the signals tested with. A hi-fi amp running within the straightest portion of the curve might give better results with one tube, while another application where the non-linearity at the extremes of the curve are listened to, like in guitar amps, will favor another tube, that might not be suitable for linear amplification applications. Saying that one brand sounds better only makes sense when describing the criteria sought and the circuit application. Those seeking linear transfer functions, as in hi-fi or recording are going to pick different tubes as the best for their ears than a guitar player who does not want a linear transfer function.
Any of them can sound better than the others if the circuit is optimized for the traits sought.

Yes, the GZ34 from Ruby is made by a small factory owned by Magic Parts/Ruby. It was an tube factory that was purchased by Tom and moved to a smaller town. It took a lot of work and red tape over years to get it operational. Tube manuals from the period when those tubes were still in production, interchange the nomenclature 5AR4 and GZ-34 but they measure differently. The Mullard GZ-34 was unique in it had less forward voltage drop so just sticking it into an amp with another full wave rectifier resulted in higher and stiffer B+. That was the reference tube that Ruby Tube used in developing their GZ-34.

[daz]

The various versions of 12AX7s all "sound" better than the others if put into a circuit that is optimized for their parameters.

Always believed that because i developed my amp over quite a few years that this is exactly true. I tweaked it endlessly always with the same tubes and speaker from day one. But that rule CAN be broken, and till recently i wasn't so sure. Every time i tried a different EL34 brand or different 12AX7 that what i'd been using from day one, it never was quite as good. Then recently i was very surprized to find that using JJ6L6 instead of the Winged C 34's was a unmistakeable improvement. I've now been using them for months and every now and then i put the winged C 34's back in to see if my ears have tricked me and every time i can't yank them out and put the 6L6 back in fast enough. Then after that i try a tung sol in V1 and same thing ! But the kicker is, i have tried both in the past a number of times and always would go back to the tubes i developed it around. I did make a few changes in recent times so i must contribute those to the reason all of a sudden those tube changes are great when they weren't in the past. Thats all i can figure. But i still believe that what you said is for the most part true. Like any rule it can be broken but it's not usual. I must say tho, i have continually impoved this amp from day one but those recent changes have it sounding well above how it did before, and thats saying something. Every little pick scrape and detail in the pick contacting the string comes out even thru a mix. The richness is beyond any amp of this type i've ever played.

Speakers i haven't messed with much, but then for decades i've always found any amp i use a EV12L in sounds better to me. I have yet to find any amp to be more favorable with anything else. They just get "my sound" far better than anything.

[Ted]

Leo, if a heater has a negative potential and it reduces hum there is something wrong elsewhere in the circuit. It could help if the "right" defect or leakage is present.

1970s Ampeg B15s actually put the wiper of the hum balancing pot to the -ve bias. I have occasionally wondered why they did this and what possible difference it could make.

The early cathode-biased amps tied it to the cathode resistor. Intermediate models tied it to 0V...

[Leo_Gnardo]

1970s Ampeg B15s actually put the wiper of the hum balancing pot to the -ve bias. I have occasionally wondered why they did this and what possible difference it could make.

The early cathode-biased amps tied it to the cathode resistor. Intermediate models tied it to 0V...

Thanks Ted. I was rackin' my atrophied brain trying to think of where I'd seen hum balance referred to - supply. Although the polarity isn't "proper", the presence of a cap to shunt AC noise to ground may be the charm.

[daz]

Sorry to bring this one back, but i just received half dozen more from tube depot and 1 was humming, 5 were fine ! I don't know what thats about. Maybe different batches, who knows. But to this point i had the exact same but to the other direction....2 out of about 12 good. Thats 1 for 6 good, and this batch i got one bad in 6. I was afraid i'd have to use something else, but this is hopeful, and 6 will probably last me till i die anyways. Last 2 i got from dougs tubes were both bad and i returned one (decided to keep one that was acceptable at best) but the replacement never showed up so for all I know that woulda been bad and made 3 for 3.