Vacuum Tube Valley (VTV) dual triode characterizers database?

Discussion in 'Amp Tech Center' started by DavidP, Oct 13, 2019.

  1. DavidP

    DavidP Friend of Leo's

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    I have some NOS 12AY7s that have gain levels noted based on a VTV 'dual triode characterizer' tester, but can't find any info on this arbitrary scale. I do know their gain scale is not actual Mu of the tube, but a tester-specific arbitrary scale used by VTV.

    Anyone got access to a database with the 'standard' preamp levels listed?

    Thanks!!
     
  2. peteb

    peteb Friend of Leo's

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    The actual Mu of the tube will be different than the measured Mu as well.



    For example a 12 AX7 tube has a Mu of 100. In actual use the Mu is more like 45.


    The 12AY7 tube has a gain of 70? If you measure the gain it will be half of that. The tube tester must test somewhat close to the normal range.


    What do yours test?
     
  3. Wally

    Wally Telefied Ad Free Member

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    One would wonder what a 12AX7 shows in relation to that 12AY7?
     
  4. rolandson

    rolandson Tele-Meister

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  5. DavidP

    DavidP Friend of Leo's

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    Thanks, rolandson. Great resource!!
     
  6. Wally

    Wally Telefied Ad Free Member

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    If VTV uses their own ‘arbitrary’ scale, the industry specs won’t directly relate to that tester’s numbers, correct?
    Are you using a VTV unit, or are you simply trying to use the VTV scale while using some other tester?
     
  7. DavidP

    DavidP Friend of Leo's

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    Hey Wally:
    I have a few preamp tubes from a now deceased tube fellow who noted VTV values for each, thus the desire to see how these relate to the standard value for that tube type. I know a few hundred VYV testers were built, but the manuals/reference values don't come up in web searches...
     
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  8. Wally

    Wally Telefied Ad Free Member

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    Alright, thanks for the explanation. I thought you had one of the testers and needed the chart that went with it. I did not take the time to go through the info in that link; but when I am curious about a tube’s specs, I go to....
    Duncan Tube Data Sheet Locator..... There are links to many different spec sheets to be had there.
     
  9. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    I don't think there are "standard" levels to be expected. More a case of are the two halves equal, and therefor suitable for differential amplifier fuctions where a close match is wanted, such as a phase inverter, certain mixers, or particular oscillators.
    Or, if measuring a batch, which ones are higher and which the lower.....what sounds the best in a circuit need not be the one with the rating 4.3 compared to a 5.6. But at least then you can tryout the two extreems for comparison.
    Or, maybe you have to replace a broken tube, and you know that a "6" works best in the circuit, then you can choose a "6" to replace it.

    A bit more information about the tester can be read here vacuumtube but a hand book for the tester....no can help.
     
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