Tube chemistry?

Discussion in 'Glowing Bottle Tube Amp Forum' started by trxx, Jan 24, 2020.

  1. trxx

    trxx Tele-Holic

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    Were there general differences in the chemistries of metals and coatings of how tubes used to be made (that NOS stuff that people are paying $$$ for) compared to how tubes are generally made today? If the general differences between NOS and new production tubes were only down to mechanicals, it seems that new production tubes could be made more consistent with modern computer controlled machinery. And for all I know, maybe modern production tubes are made more consistent, where differences are in the chemistry. I am not saying that is the case. I'm asking the question. Has there been some major chemistry changes for audio tube components, along the lines of what happened with phasing out lead solder in manufacturing in favor of lead-free? And I wonder if anyone out there has spent time and published info on that.
     
    Last edited: Jan 24, 2020
  2. W.L.Weller

    W.L.Weller Tele-Holic

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    The production lines and associated institutional knowledge are long gone.

    But mass spectrometers only cost as much as a new Camry, the NOS-cloning fruit is just ripe for picking!
     
  3. Commodore 64

    Commodore 64 Friend of Leo's

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    Well, thoriated tungsten is used on the cathodes. Not sure whether today's thoriated tungsten is better or worse.

    The tooling in the tube factories is old and worn, by some accounts. So tolerances might not be as tight.

    Personally, I suspect the biggest difference between old stuff and new stuff is the QA/QC. It's less stringent now.

    I have no qualms with using new production tubes. I don't get into the tonal alchemy/worship of NOS, either. I'm the one who sets the operating points of the tubes, after all.
     
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  4. dan40

    dan40 Tele-Afflicted

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    I have read that every manufacturer back in the day had their own recipe for plate and cathode coatings and kept it a closely guarded secret. Back then everything ran on tubes and the military was one of the largest users. Quality control had to be kept to a high standard for those companies to be successful. While the factories did rely on machinery to make many of the tube parts and internals, the tubes were hand assembled by highly skill workers. Unfortunately most of those skilled workers, scientist and engineers are now gone as is the knowledge that they possessed. Today's amplifier industry makes up such a small percentage of what tube sales were in the past, so there are only a few factories left in the world that are still manufacturing tubes for audio use. Investing a lot of money in new machinery, R & D and worker training may not be economically feasible for those factories in today's digital world.
     
  5. BobbyZ

    BobbyZ Doctor of Teleocity

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    Pittman was going to make tubes in the States several years ago. That never panned out. As I recall he bought a bunch of old equipment from GE. But even though he owned Groove Tubes he didn't have the financial means to start up production in the States. It'd take millions of dallors to do that here today and let's face it the market just isn't there to make that an economically feasable investment.
    Let's say you get up and running for five million. How many 6V6s and 6L6s do you gotta sell to clear 5 million dallors?
    We're not even talking payroll yet. Which would be expensive because you'd have to reanimate dead people to get a knowledgeable work force. :)

    Just be glad there's three or so factories left in the world still making pretty good tubes.
     
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  6. powerwagonjohn

    powerwagonjohn Tele-Meister

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    There is/was a company in England that was getting ready to make tubes. Last I read they were refurbishing the old manufacturing equipment. I am sure someone here has a link.
    Thanks john
     
  7. dan40

    dan40 Tele-Afflicted

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    https://brimaruk.com/

    As far as I know, they have not yet been able to start producing their own tubes yet. They are selling current production tubes with their branding though.
     
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  8. W.L.Weller

    W.L.Weller Tele-Holic

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  9. LightningPhil

    LightningPhil Tele-Meister

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    Correct, Brimar aren't making tubes yet. Getting closer, but won't be starting with ones suitable for guitars. It'll be similar to this:
    https://www.mhs.ox.ac.uk/collection...?thumbnails=on&irn=15556&TitInventoryNo=80773

    Presently, they're getting pinches working well for the valve stems. Next step, it'll be evacuating the tubes and then heating to purge them. They're doing a proper job of starting with the basics.

    The old evacuating systems used mercury diffusion pumps on a rotary table to get a reasonably good vacuum, while heating with a huge amount of RF.

    Fun fact, the blue glow seen in some tubes is very likely mercury contamination!

    The new system will use a turbo pump with no chance of contamination, and a longer purge time to ensure awesome vacuum goodness. I'm building their dev system in my garage...

    While it's true that a lot of the know how has vanished, it's not completely gone. I've a history of designing x-ray emitters (more usefully, have a few contacts with a longer history here too) and working with high vacuum. And the chap who's sorting out the RF systems for heating has had a career doing so for the food industry.

    There are certainly some chemistry questions that would be great to find answers for. But fortunately, electron emitting systems have some parallels in experimental physics, so some gaps may be filled in as we go.

    Oh, should mention, only got involved so I could make some awesome power tubes from scratch. It'll be a long journey but fun! One done, they should be available for others too.
     
    Last edited: Feb 1, 2020
  10. rangercaster

    rangercaster Poster Extraordinaire

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    Imagine trying to replicate 1940s automotive technology ... can be done. .. but very likely not profitable...
     
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  11. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    Take the 6V6 as an example.
    First made by Kenrad in autum 1936, and since then, in some form, by some company, somewhere, never gone out of production.
    Since then, the tube has had, other than envelope options, no significant changes to the original tubes parameters registration - Transfer functions, minimum voltage and current handeling, filament current draw, socket pin consignment...etc.
    Compared to the small round grey plate Kenrads, the oval plates made by several other companies 6v6's that came out in '37, where a structral change. a bit later we find "box" plate forms, being formed by a different method, that had a granular effect on the metal. Then there where black plates, which had a different composition to the coating. Plates started to get bigger and longer in some later generation tubes in the 1970's. The alloys where also changed.
    The chemical/mineral makeup of the cathode material went through several updates through those first 35 years......all improvements? The makers thought so, and I'd agree.
    [​IMG]
    These east German 6V6 tubes of mine, from 1949 had a totally different construction, and probably different material composition.......yet they are still great 6V6 tubes. As are Many Italian, French, Hungarian, Japaneese, Sweedish, Russian....(you get the picture)........but there where also lots of lower quality ones around as well.....even back in the 1950's. The better factories always released better tubes, some of the russian factories had cheap consumer tubes, good military, and best military versions.

    So back to answering your question...........There where always differences to how they where made then.....whenever then was.
    As to how they are made now; it is just an ongoing story, they are now made like they always where made; different from all the others. I think the burning in and testing in the quality control of the producing factory is a thing lacking now, due to costs.

    And yes....the JJ6V6S is a great tube, and it is a true 6V6 (dispite what others may say.) But, there are reports of lower quality versions of their tubes being sold, with reliability problems. But buy them from a good handler who burns in, tests and matches the tubes, then they are as good. or even better than many tubes of yesteryear......and a lot cheaper.
     
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  12. Apache Snow

    Apache Snow Tele-Meister

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    In the General Electric tube plant in Owensboro Kentucky, they used women they hired of the street to assemble the tubes. Im retired from GE. They turned the tube plant in to an AC electric motor plant. They kept the tube work force. I have been in that plant and talked to many of them. I don't remember GE having any scientist there. Of course GE always had good engineers in their plants. I was a process engineer.
     
  13. LightningPhil

    LightningPhil Tele-Meister

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    An x-ray spectrometer is better for solid high temperature coatings than a mass spec - as you'll never get it to evaporate, and thus ionise. Like one of these:
    https://www.amptek.com/products/cdt...ray-gamma-ray-spectrometer-with-cdte-detector

    Not only are they way less expensive (around $10k) than a mass spec, it seems they're worth nothing at all second hand (which is why I've not bothered selling my one).

    Smashing tubes and zapping their innards sounds like a good summer project.
     
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  14. jvin248

    jvin248 Poster Extraordinaire

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    All the different construction techniques and materials metallurgy of the tubes old and new were designed to a tolerance input/output specification. Otherwise you'd burn out someone's delicate lab instrument or shock a rock star on stage. One pin had to see 500 volts in order to send 12 volts out of sound signal from the audio coming in at 3 volts on yet another pin.

    So while it might be fun to speculate about the construction differences, you can in effect treat them as a black box with known input/output expectations. That's why you can buy equivalent tubes by different vendors/factories.

    If you are seeking slight tone differences ... the pots on a typical guitar vary by a 20% range guitar to guitar. Pedals have pots that vary by 20% and thus two 'identical pedals' will need their knobs set slightly different from each other to sound exactly the same.

    .
     
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  15. LightningPhil

    LightningPhil Tele-Meister

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    I vary by significantly more than 20%. Depends quite heavily on coffee levels.
     
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  16. muchxs

    muchxs Doctor of Teleocity

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    Last I heard they were absolutely struggling to get their process under control. They were only able to produce expensive tubes of mediocre quality.


    Triumph's motorcycle factory took numerous direct hits during WWII. The damage was extensive enough they relocated to a new facility in Meriden, same factory where every classic era Triumph was made until they faded away around 1980.

    Triumph switched over to SAE fasteners by 1970. Had problems with their early five speed gearboxes by 1972. A wave of old timers retired around that time. They called one old timer in to try to get their process under control. Apparently, a gear shaper ("hobber") was incapable of consistent work.

    Old Timer took one look at "his" machine.

    (In a thick working class English accent) Old timer asked,

    "Where's Plank?"

    and was met with a blank look.

    He asked again.

    "Where's Plank? Hobber don't work without Plank."

    When pressed, Old Timer explained that Hobber's frame had been cracked when the factory collapsed on top of it during The Blitz. The solution was an oak plank that was pounded into Hobber's frame to damp vibration and take up the slack. Same greasy old board had been in there for thirty years. When Old Timer retired it was discarded. Just another greasy old board...

    :lol: :lol: :lol:
     
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  17. LightningPhil

    LightningPhil Tele-Meister

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    They're (we're) not producing any yet, so quality isn't a present issue.

    The machines are being refurbished and learning is being done. A particularly cool modification to an old grid winder is to replace the cams with CNC driven ball screws. This is handy as there only seems to be 1 cam with it, so only 1 grid style could be wound without CNC. Seems someone indeed threw the plank away before shipping the stuff to the UK. A shame, but it'll be more flexible in the long run.

    The first valves will, as mentioned above, be type R triodes, which did indeed vary quite a bit. Mainly due to the hand wound grid. But they'll only be as variable as the originals. Remaking a bit of history before moving onto higher end stuff.

    Personally, I'm in it to build a set of 300B valves from scratch.

    Randomly, rambling on a bit... I will be experimenting with vacuum for 12AX7 valves, as I have loads of em. So will be puncturing them and sticking a capillary tube on to flood with air, then purge and see how well they work. Some will get broken and some will survive and be tested in guitar amps. And in the longer run, we'll get nitrogen purging working to flush out as much argon as possible and allow a really good vacuum. We're aiming for the vacuum levels to be unnecessarily good.
     
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  18. printer2

    printer2 Poster Extraordinaire

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    I used to work in a brewery (yeah I know did not get much better than that) and for a number of years I worked with a buddy of mine on a production line packaging the bottles. Machinery from the 50's I would guess. We wrote a manual on running the machinery. It was really hard describing what you had to do to make the stuff run. A change in humidity distorts the cartons and you have to adjust for it. "When running this, you have to put an elastic band around this." You had to pay attention and be ready to jump and do whatever to keep things running otherwise you end up with broken glass and beer soaked cartons everywhere. The reason I could not learn to play guitar ten was I always ad cuts on my finger.

    They let my buddy and I go on holidays at the same time once. When we got back they would never allow both of us gone. The plant went from running 90% efficiency down to about 55%. When I left there I got a technology diploma and worked in production environments. I was good at troubleshooting but one thing I never discounted was the knowledge the guy on the line knew, process engineers with institutional knowledge. There is a reason plants need tweaking when starting up. I used to work on the machine that bottled the beer also. Two older guys did also, "Haywire" would have it running and Mike would get him for his break. Mike would look at it and say it is all set wrong, you have about a half dozen things you could adjust to get it to fill right. He finally get it set to how he likes (bottles filling just as well as for Haywire) by the time Haywire got back. Haywire takes over, sees how things are set and spends fifteen minutes getting it back to how he runs it.

    Worked in a metallurgical test lab, we got different batches of the same material and I would do receiving inspections of it, testing their properties and the stuff would not be used until I tested and passed the stuff. The stuff we got varied, and even though it passed there would be problems using it. he company tried to lean itself out, why do we have all these process engineers, write up how to make the part and get rid of most of them. Then they had problems. "Didn't we have this happen years ago?" "Yeah, what did we do to fix it?" Darn process engineer that they got rid of knew.

    Back to tube stuff, from another site.

    The coatings allowed as many electrons to be boiled off using half the power as an earlier tube.
     
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  19. LightningPhil

    LightningPhil Tele-Meister

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    We could make cathodes out of Nickel 63 to enhance electron emission. Would need thicker leaded glass bulbs though.
     
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  20. muchxs

    muchxs Doctor of Teleocity

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    It's good to hear you're making progress! I'm sure it's a daunting task.

    Make 'em good then make 'em better.

    Couple buddies of mine were in semiconductor design and production. If we can etch a quarter million "junctions" on a tiny piece of silicon... well, a 12AX7 is the size of the space shuttle by comparison.
     
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