The Dynaco Tube Audio Forum

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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


3 posters

    One tube is brighter

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    Dogstar


    Posts : 361
    Join date : 2014-06-23

    One tube is brighter Empty One tube is brighter

    Post by Dogstar Mon Jan 18, 2016 10:35 pm

    I had another amp and preamp running for a while and just went back to the VTA ST-120 and I just re biased the tubes with a new multimeter. The 25 year old Fluke 85 I was using died. Anyway...I noticed the right front tube is brighter than the others. I'm using TungSol KT120's. Is this ok? If not what should I check? Thank you.
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    GP49


    Posts : 792
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    One tube is brighter Empty Re: One tube is brighter

    Post by GP49 Mon Jan 18, 2016 10:43 pm

    What looks brighter? The visible filament? I wouldn't worry about it. Maybe a bit more of it is exposed so you can see it; that's normal production tolerance.

    If ANY part of the plate is red, however...another story.
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    Dogstar


    Posts : 361
    Join date : 2014-06-23

    One tube is brighter Empty Re: One tube is brighter

    Post by Dogstar Tue Jan 19, 2016 9:04 am

    The filament is the brighter part. The tubes probably have 300 hours on the. Performing perfectly ok. Thanks.
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    GP49


    Posts : 792
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    One tube is brighter Empty Re: One tube is brighter

    Post by GP49 Tue Jan 19, 2016 6:52 pm

    Enjoy the music!
    deepee99
    deepee99


    Posts : 2244
    Join date : 2012-05-23
    Location : Wallace, Idaho

    One tube is brighter Empty Re: One tube is brighter

    Post by deepee99 Fri Jan 22, 2016 7:42 pm

    It could just be a line of sight matter, especially if the key-ways are in different places. I have a couple of tubes whose filaments look brighter than the others, until I can eyeball them from exactly the same perspective and from the top, in which case they all look pretty close (unless you've got getter flashing on top, in which case only a side view works). Same holds for novals, if they're centred differently on your chassis.
    As GP 49 says, Enjoy the music. Or as I have learned, if it ain't broke don't fix it.

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