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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


    My vintage ST-70 needs new tubes

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    ferpromo

    Posts : 3
    Join date : 2020-08-26

    My vintage ST-70 needs new tubes Empty My vintage ST-70 needs new tubes

    Post by ferpromo on Wed Aug 26, 2020 4:56 pm

    My vintage ST-70 needs new tubes Img_5918 My vintage ST-70 needs new tubes Img_5917
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    mijohn

    Posts : 92
    Join date : 2013-06-19

    My vintage ST-70 needs new tubes Empty Re: My vintage ST-70 needs new tubes

    Post by mijohn on Thu Aug 27, 2020 5:43 am

    The right front EL34 tube in particular is obviously kaput as it has lost its vacuum!

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    anbitet66
    anbitet66

    Posts : 144
    Join date : 2009-12-23
    Location : Valley Stream, NY

    My vintage ST-70 needs new tubes Empty Re: My vintage ST-70 needs new tubes

    Post by anbitet66 on Thu Aug 27, 2020 11:51 am

    And the right rear looks to have run so hot as to have consumed most of the getter flash.  That side may have a bias issue caused by leaky coupling capacitors.

    This is an amp that will greatly benefit from a simple re-cap and a set of output tubes.  Though, a more thorough going over would be nice, but in many cases not needed.

    I have a vintage unit that is all original, 'cept the output tubes on one side and she still biases and sounds fine.  A new quad cap is on the horizon just in case.

    Good luck with it.  Tony

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    ferpromo

    Posts : 3
    Join date : 2020-08-26

    My vintage ST-70 needs new tubes Empty Enjoying it now

    Post by ferpromo on Sat Sep 26, 2020 1:00 pm

    My vintage ST-70 needs new tubes Img_6711 My vintage ST-70 needs new tubes Img_6710

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    My vintage ST-70 needs new tubes Empty Re: My vintage ST-70 needs new tubes

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