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Audiophile Q&A: Scarcity of NOS (new old stock) audio tubes

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Dear Phillip,

Just sharing a thought, during my little trip down south, my brother and I talked about tubes in general. The interesting question popped up was, how come we could not produce tubes of the past like the ECC803S, Genalex Gold Lion, Gold Monarch, EL34 metal base, Mullard EL35 and so on, with our current technology. Just analyze the material used and replicate it. Is there something about tubes we, the general public does not have the knowledge or are the manufacturers controlling the market interests, or is it us being too gullible by accepting what’s been said? Then again to validate it, one must spend the money where most may not have. Anyway, I am frustrated and could not accept the fact of the big price differences and the quality between the old and new.

Best regards,
Ben

High quality tubes are still made, as good as any made 50 years ago, but they are all very expensive high power RF tubes (and similar). Those are carefully assembled in clean room environments, then pumped to adequate vacuum and the whole process has no concern for speed or cost, only the customer’s exacting specifications. A 100,000 watt broadcast tube will cost as much as a car, but then again, a TV or Radio station could lose much more money if they were to be off the air for a couple weeks.

So, why can’t we have tubes as good as yesteryear’s? Here are my thoughts:

Indirectly heated tubes require incredibly pure cathode emulsions for long life. Very small contaminations can “poison” the cathode, leading to much shorter life and lower emissions.

Incredibly old equipment is being used. The equipment is sometimes twice as old as the people using them. The people who designed and built the machines are dead and most of the subtle tweaks of fine tuning such machines are lost. Today, with ISO certification, there are records of any time a screw is turned a certain way, but not back in the ’30s-’60s. Much of this equipment actually needs to be rebuilt and/or replaced; but there aren’t too many options for sourcing such equipment. It can be done, but it’s not as easy as it was 50 years ago.

Finally, most audiophiles and musicians are not willing to pay what we should be paying for electronics. The avalanche of cheaply produced electronics has given people the impression that anything electronic is easy to make and should be cheap, or they are being screwed. If you look at what people had to pay for a top quality ECC88 in the ’60s, it was much more expensive back then when adjusted for inflation. People don’t want to pay $100 for one tube (there are exceptions, of course). This “cheap” attitude has kept prices low and starved the tube manufacturers of much needed investment capital.

Many people have also adjusted to the poor quality of today’s tubes: The guitar players really don’t need top notch tubes. They run them full out, and distortion is what they are looking for, not linearity. Sure, the old tubes had different tone, but a Russian EL34 can come close to a Mullard when being over-driven by a heavy metal thrasher. The front-end circuit of a guitar amp makes most of the tone, that’s where overload and distortion is designed into the amp. After that, the speakers are more important than the tubes: the old guitar speakers used AlNiCo magnets and paper cones, just like the really good audiophile drivers. For quite a few years, those kinds of “musical instrument” drivers got really junky: no Alnico, plastic cones, rubber surrounds. Rubber is not a good surround material for guitar tone.

Another example of how we deal with bad tubes: High-end audio manufacturers run their power tubes at lower voltages than the designs from the ’50s. I remember Sovtek EL34s turning bright red because they couldn’t handle the screen grid current in my Altec Lansing 1569a amps. The plate voltage was safe for junk tubes, but not the screen grid voltage, which caused runaway current. By the way, those Sovteks were absolute crap. In a supposedly matched quad, one had an intermittent short, and one was already showing “leakage”. That happened with two straight sets of tubes, then I switched to “Winged C” which had much better quality control (also Valve Art–not as good as Winged C, but better reliability than Sovtek and better sound than JJ). I will admit that it was a while back, but it is a valid anecdote of the lack of quality from the people who run Sovtek, and the other names they call themselves. Their 300Bs were pretty good though, and better sounding than the JJ 300b.

So, finally, are there good tubes being produced? Yes. The hope for success is with directly heated filamentary tubes. Tungsten wire can be purchased that is very pure. Thoriated tungsten can more easily be made with the necessary purity, than the cathode emulsions needed for indirectly-heated tubes. High purity plate materials, like copper and nickel, are available. The key to success, then, is the tube manufacturer’s ability to put the thing together correctly and pump it to very high vacuum. By the way, we will never again see high quality frame-grid tubes.

I think that the directly heated tubes from China are quite good and are getting better. If I am correct, I think the Chinese tube manufacturers are ISO manufacturers of other consumer goods, and the quality control standards that are a requirement for those other products probably have an impact on how the Chinese handle quality on everything else. Honestly, I just think that the Chinese are more serious about quality manufacturing techniques than the Russians; the Russians, like we Americans, are more consumers of electronics than makers. What would be nice would be if Hyundai made tubes, or Mitsubishi. The South Koreans and Japanese have mastered quality control, and they seem much less likely to let their machines get out of tune and fall apart. That’s only a dream though. I doubt we will see any new tube plants built, full of shiny brand new equipment. On the other hand, some of the plants that made CRTs (until recently) might try to get into audio tubes. CRTs are much more difficult to build and those production lines are more modern and of higher quality.

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2 Responses to Audiophile Q&A: Scarcity of NOS (new old stock) audio tubes


  1. peterj says:

    Most people seem unaware of the use of rare earth metals in NOS tubes – as opposed to current production versions. Such materials are now prohibitively expensive for tube manufacture at least. China effectively controls world supply.

  2. phillip holmes says:

    Since China clamped down on rare earths, production has increased everywhere that isn’t Asia. Because prices were dirt cheap, and extraction costs were high, the US mine that produced the bulk of what the US consumed shut down in 2002, before the huge boom in smart phones and tablets, which require relatively large amounts of rare earths.. China developed their own rare earths mining sector, sold it cheap, then caused an unwarranted panic. The prices spiked due to speculation, not short supply. When they peaked, everyone started looking for rare earths, and found them all over the place (just because they are called “rare”, doesn’t mean they are that hard to find–it’s not Astatine 210). Prices are way off their peak. The most expensive metal used to produce vacuum tubes is tantalum. Old directly heated tubes used plates machined from billet tantalum. The tantalum acted as a getter. When the tantalum started glowing cherry red, it “took up” the residual gas in the vacuum. That’s why they glow red on purpose.

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