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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


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    Can 6GH8 plug n Play on VTA ST-120 ?

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    EddieGnz1


    Posts : 23
    Join date : 2013-10-17

     Can  6GH8  plug n Play on VTA ST-120 ? Empty Can 6GH8 plug n Play on VTA ST-120 ?

    Post by EddieGnz1 Wed May 28, 2014 10:22 am

    I found a way to buy a 6GH8 that someone was using on their ST-70. Will it work as the center tube on the ST-120 driver board ?

    thanks,
    Eddie
    avatar
    GP49


    Posts : 792
    Join date : 2009-05-01
    Location : East of the sun and west of the moon

     Can  6GH8  plug n Play on VTA ST-120 ? Empty Re: Can 6GH8 plug n Play on VTA ST-120 ?

    Post by GP49 Wed May 28, 2014 11:33 am

    No, you can not do that.  

    Not only do the pinouts differ; the tubes are of two different types.  

    The center tube of the ST-120 is a twin triode, nominally a 12AU7.  The 6GH8A is a pentode-triode.

    "Someone" was probably using the 6GH8 to replace the 7199 pentode-triode in a STOCK Dynaco Stereo 70 (a wiring change is required, the 7199 has yet another different pinout) but that amp has a totally different driver/inverter circuit from that in the ST-120.

    6GH8:

     Can  6GH8  plug n Play on VTA ST-120 ? 9ae

    12AU7:

     Can  6GH8  plug n Play on VTA ST-120 ? 9a

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