12AX7s measured on tube tester, results

Discussion in 'Marshall Amps' started by Force235, Sep 21, 2019.

  1. Force235

    Force235 Well-Known Member

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    Spent some quality time with a tube tester the other day, checked a bunch of my pre-amp tubes I've collected over the years, what I found was interesting.

    Fairly new Sino's - all over the map, Em - 850, 1350, 1000, 900

    JJs - rock solid at 1000
    1980s Nationals - 1100 solid, 7 of them
    Phillips (new) - 1100
    GTs - rock solid 1000

    I'm not sure if the Sino's, being all over the place, helps create a more unique tone, could be, and you could be very happy with it. That said, they are not consistent, which would mean, you may get that tone again!
     
  2. SkyMonkey

    SkyMonkey Well-Known Member

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    Sorry. Not all that clued in on the actual inner workings of a tube.

    Can you explain what you are testing for.
    What is the measurement (e.g. volt, amps, ohms?).
    What effect does that have in the real world?

    We are not all experts.
     
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  3. Jon C

    Jon C Well-Known Member

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    Yeah , a layman’s explanation of what the values are would be awesome …… I get that you’re looking for consistency
     
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  4. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Define what tube tester you're using as well. I use a B&K Dyna-Jet 707 and its number calibrations are different from yours.

    I would expect the cheap Chinese tubes to be all over the place. They'll ship anything that's functional. Leave it up to the reseller to sort them for quality and match them. Age them and test again for drift and general performance.

    I can tell you that the 707 is a good enough tool that I can use it to match up tubes in sets with it. The matched sets can then be installed in an amplifier, checked for current draw, and be verified as actually being a close match.
     
  5. Force235

    Force235 Well-Known Member

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    OK, more info later, goot a run out
     
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  6. Trelwheen

    Trelwheen Well-Known Member

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    !!!! Have you tried Pepto Bismol? :hug:
     
  7. dragonvalve

    dragonvalve Active Member

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    It would be helpful if you state what tester you used.
     
  8. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    If you do not provide the tube tester used for the scores none of that means much, at least to a technical person.
     
    Last edited: Sep 27, 2019
  9. Matthews Guitars

    Matthews Guitars Well-Known Member

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    I recently sold my Mesa Triple Recto head. It was just not my tone. However I am going to miss it from the standpoint of the fact that it made an excellent performance tube tester. I found that it could tell you a great deal about the tone and usability of any 12AX7 tube in a specific socket. I'd set it to the clean channel, in boost mode, and be able to sort out tubes by gain and noise and check for increasing Miller Effect as the tube ages. I'd have to check my notes again but I believe that I did those tests in socket V1.
     

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