Why were tubes better in the olden days?

Discussion in 'Amps and Cabs' started by Corinthian, May 4, 2015.

  1. Corinthian

    Corinthian Member

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    Inspired by a couple of threads at the moment about new and NOS tubes. What specifically separates the great old tubes from the ones being made today?

    I don't mean the reasons for the old ones being made better; more demand, military use requiring higher quality etc. Etc. What is it about the actual tubes that was better? Were they made with higher quality metals? Did they use materials that are outlawed now? Were they able to achieve greater vacuums?

    And as a follow up; what makes it so difficult / costly to produce valves to a similar standard today?
     
  2. SteveO

    SteveO Member

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    You mostly answered your own question. The biggest demand for tubes up until the 70s or 80s was the US military, and they set stringent specifications for quality, longevity, and durability. The countries still producing tubes presently don't have those same quality levels to maintain, so they don't.

    The cost factor involved is due to the process of manufacture. Tube production is a very, very dirty endeavor, and modern environmental regulations make it nearly impossible financially to produce tubes stateside.
     
  3. DaveKS

    DaveKS Member

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    Well think of it this way, if you wanted to put same amount of resources and technical knowledge and expertise into making tubes of that quality again, you'd probably need a good chunk of Nasa's budget and a good chunk of their scientific/engineering staff and quality control specialists. Just reality, they were mission critical back then, now their just a niche audio amplifier circuit.
     
  4. zenas

    zenas Member

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    The US ones where made in a the golden era of of the American middle class. I'm sure that helped but have no solid data to back up my thoughts on the matter.
     
  5. VaughnC

    VaughnC Supporting Member

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    Specs on tubes were tighter back in the day as they were used in critical military, communications, & aerospace applications. Then the transistor made tubes obsolete and their demand dwindled as tube based equipment was retired. Not enough guitar players in the world to keep up the demand for tubes so the big boys shut down...and the Chinese stepped in to try and fill the tube void for us guitar tone hold outs. I've had preamp tubes last 15+ years in the good old days...but not today ;). I worked on a local guys amp one time where the preamp tubes were actually rusted into their sockets, but the preamp section was still working ok!
     
  6. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Tubes were once used in every electronic device, worldwide. They were a common commodity and made in very large quantities. Today they are used in a fraction of 1% of all electronic devices.

    Therefore, much manufacturing resources and top engineers were dedicated to their production.

    I don't buy into the hazardous materials talk that always crops up in these threads. There are MANY products made today that utilize hazardous materials. It comes down to economics. There is far less money to be made producing tubes
     
  7. Bieling3

    Bieling3 Member

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    Capitalism. When the Government is your biggest customer with specific requirements on quality, you have to meet them. When you're selling to the general public with nothing but the market to oversee things there's the usual downward spiral of cost cutting in quality and labor, etc, etc, until everything is efficient and profitably as possible and planned obsolescence kicks in and you're at the tube docter's site ordering yet another 12ax7...
     
  8. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Think of tubes as the silicon chips of yesteryear. Now they are all but obsolete. A novelty.
     
  9. JB6464

    JB6464 Member

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    Better building materials used back then and they were made by people who actually cared about quality , imho .
     
  10. davebc

    davebc Member

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    When used in military applications, tube failure was not an option.
    Lives were be on the line.
    Not quite the same standards today.
     
  11. CRUE

    CRUE Member

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    This.
     
  12. Chrome Dinette

    Chrome Dinette Silver Supporting Member

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    1. Care taken with grid windings(and other construction details)

    2. Care taken with chemistry used for cathode coatings

    3. Hardness of vacuum
     
  13. Blue Strat

    Blue Strat Member

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    All of the above but, in the final analysis, this...
    TODAY.
    In the 60's tubes were like microprocessors, memory, and video chips/processors today in terms of sales volume and profitability.

    Today's tube guitar amp and audiophile market is insignificant by comparison.
     
  14. Corinthian

    Corinthian Member

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    I think everyone has misread the question. I'm not asking about the economics surrounding it, or where the demand came from etc. It's easy to understand why tubes were better back when. I'm asking about how they were better. What is it about the tubes themselves that is different?
     
    Last edited: May 4, 2015
  15. Corinthian

    Corinthian Member

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    This is the kind of thing I mean. Can you elaborate?
     
  16. Blue Strat

    Blue Strat Member

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    I'm not sure anyone's qualified to answer that with authority since none of us knew how to produce tubes in the first place.

    General consensus seems to be materials and experience. If the economics were better, these things could be compensated for...possibly.
     
  17. Vox66

    Vox66 Member

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    Plate voltage handling and tone.
     
  18. Chrome Dinette

    Chrome Dinette Silver Supporting Member

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    I can't remember where, maybe an issue of VTV, that had pictures of new and vintage grid windings in the Sam model tube. They looked quite a bit different, newer tube looking more haphazard. I'm no engineer, though.

    This article explains the various aspects of construction pretty well:

    http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm
     
  19. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    I agree with these considerations, and would also argue that quality control on materials and production techniques are the reasons for vast differences between classic era and current production.

    #3 isn't solely about how low the negative pressure could be drawn with the vacuum pumps. It has to do with getter material distribution and the quality of the metals and mica spacers used. Poorer quality materials can be a source of outgasing, and that leads to earlier tube demise.

    How did the vintage greats control materials quality? Mostly by self-sourcing. For instance, the venerated Mullard (Philips) company smelted their own tungsten from raw ore, and drew their own wire:
    http://www.r-type.org/addtext/add044.htm

    Tubes were carefully tested after production, with batch monitoring so processes could be improved, and the origin of faults identified. Nowadays it seems like current-production rejects go to eBay. But here is what Sylvania and RCA did with factory rejects:
    [​IMG] [​IMG]
    [​IMG]

    There is also difficulty simply obtaining and maintaining extremely specialized machinery. No one is making tube-manufacturing machinery anymore, nor are there replacement parts available. Simply setting up modern tube production takes incredible capital, and very skilled tradespeople.

    This interview of Aspen Pittman, from Groove Tubes, sheds relevant light on this topic:
    http://www.legendarytones.com/aspen-pittman-interview/

    - Thom
     
  20. Blue Strat

    Blue Strat Member

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    ^ I'm always amazed when people who buy, below market price, new production tubes on Ebay are surprised that things don't work out. ;)
     

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