Help: Tube Identification

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jjones, Feb 15, 2009.

  1. jjones

    jjones Member

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    I have some tubes that the lettering has burnt off and don't know if they are two 12AX7's or one 12AX7 and one 12AT7? The internals definately appear to be different but that is all I can observe. Can anyone provide some insight?

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    Last edited: Feb 15, 2009
  2. thilton59

    thilton59 Member

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    The one on the right looks very similar to one I have, does it have a square getter?
     
  3. jjones

    jjones Member

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    Yeah it does have a square getter. Do you know if it a 12AX7 or 12AT7?
     
  4. fisheric

    fisheric Member

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    the one on the left i am almost sure is a 12ax/u7

    the one on the right could be either one. its a chinese tube of some sort, but i have both a 12ax7 and a 12at7 with the same plates and same getter. the only way to tell is stick the one on the left in an amp and play it. then stick the one on the right in and play it.

    if the one on the right is softer or louder you will know if its a at7 or ax7 respectively.
     
  5. thilton59

    thilton59 Member

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    I think it's an at7, that's based purely on it's sonic values though. (I just A/B 'ed mine with a JJ ecc83s as the control) The unknown tube has a bit less gain, but has more clarity.
     
  6. rockon1

    rockon1 Member

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    The one on the right is Chinese. Cant ID the one on the left-not good enough picture of the plates. Bob
     
  7. Swarty

    Swarty Member

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    The left one is a Tungsram.
     
  8. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Yep - note the tell-tale plate shield
    Yep - note the tell-tale square numbered tag on the getter support wire.

    Good calls, guys.

    - Thom
     
  9. 59Vampire

    59Vampire Silver Supporting Member

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    good eye! i cant beleive i missed the telltale little plate! Since I have never seen a tungsram12at7 im guessing ax7!
     
  10. fisheric

    fisheric Member

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    :hide aww where are my kudos?


    where is the tag? which picture do you see it in?
     
  11. rockon1

    rockon1 Member

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    Me niether. I only own own about 25 of them. Time to stop squinting and use my reading glasses. :messedup Bob
     
  12. jjones

    jjones Member

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    Thanks:BEER
    I did order some Tungsram a long time ago and it must have gotten mixed with the old tubes I had from a stock DRRI.

    It's nice to know there are places like this someone can go and get the answers they need. Much appreciated!
     
  13. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Oops! :eek: You've got some karma credit coming your way.
    The first photo, the tube on the left: there's a little square tab on top of the upper mica disks. Though you can't read it, there's always a number on the tag.

    - T
     
  14. fisheric

    fisheric Member

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    ooooh. i thought that was just a reflection on the glass
     

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