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Thread: Sovtek EL84m tests poor in Orange valve tester??

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    Sovtek EL84m tests poor in Orange valve tester??

    I received a new quad of EL84m from TubeDepot today.. I've been using my new Orange tube tester for a few months now. These tube test quite low, in the worn range. They all test 4 on an LED scale of 16. The tubes did not fail (a LED which will indicate a bad tube). This is for a retube of a Vox AC-30. Anyone else notice this? The tester only checks tubes used in audio amplifiers, so it's very limited. It can be used to check matching of tubes. I do like the unit & has been helpful in amp repair. This is the first time anything odd has happened.

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    Lifetime Member Enzo's Avatar
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    So they are OK, but low gain. (or whatever)

    SO how did they work/sound in the amp?

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    Haven't installed yet.... but will let you know....

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    Supporting Member Jazz P Bass's Avatar
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    "They all test 4 on an LED scale of 16:.

    I do believe that if a tube works, it is shipped from the factory.

    So they are 'low gain' tubes.
    The overall output will be lower than a '16'.
    But who will notice a few watts output.

    Groove Tubes would have placed a '4' rating on the sticker.
    At least they were honest.

    Hey, at least they are 'matched'.

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    Hopefully they compensate by being low-microphony and long-lasting. Some vendors have gain groupings for EL84s but I haven't actually noticed that much difference between them when fitted. If you didn't have your tester you'd maybe have fitted them and never given them a second though.

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    I have read many reviews on those testers. One of the complaints was that sometimes it tests a good tube, bad.

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    Lifetime Member Enzo's Avatar
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    Well, no tester can be 100% all the time.

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    Well got the tubes installed. Changed the cathode resistor for less current draw. Everything is fine.... Let's see if they hold up and last...?? The AC-30 isn't fun to work on.....

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    Bent Member Chuck H's Avatar
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    Quote Originally Posted by 1ampman View Post
    Well got the tubes installed. Changed the cathode resistor for less current draw. Everything is fine.... Let's see if they hold up and last...?? The AC-30 isn't fun to work on.....
    Did you change the cathode resistor because the Sovteks draw more current than the original tubes with the stock cathode resistor value?

    IME the Sovtek el84 IS a little lower gain, but sound just fine and have a smoother OD tone (for better or worse). They're tough and can take plenty of current, but probably not mechanically tougher than the other offerings and do become microphonic in a similar time frame in combo amps.

    FWIW we don't actually know what criteria the Orange tube tester is using to "grade?" the tubes. So it could be gain, current draw, frequency response or some combination. Unless instructions for the unit tell you what "4" means all you know is "4". Since many modern tube types aren't made and don't perform just like they use to it seems possible to me that a tube that isn't what Orange defines as an el84, but is still a valid tube, might test poorly in their unit without that result being an accurate indication of ware.

    JM2C

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    Well, it's been a month & all is well. The tubes I replaced were Shugang & burnt up. So I checked the current draw & changed the cathode resistor... The plastic air vent on top was distorted from the heat. Even with proper bias they run hotter than hell. We'll see how long it takes to come back. It's a young buck and seems to pound his gear. I did my very best and would hope it lasts a year before he blows it up.

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