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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


5 posters

    Upgrade VTA ST70 to ST120?

    polarflux
    polarflux


    Posts : 49
    Join date : 2010-02-12
    Location : Alaska

    Upgrade VTA ST70 to ST120?  Empty Upgrade VTA ST70 to ST120?

    Post by polarflux Sun Feb 26, 2017 7:02 pm

    What would I have to do to upgrade my VTA ST70 to a 120. New power tranny, add the power supply under the hood. Isn't there a second choke as well? What else. I have the burly chassis so I would be good to go there. Sort of the reason I'm interested is that I prefer running KT88's. The amp would run cooler and I would have some extra juice to run less efficient speakers. Worth the $? Has anybody else done this?
    arledgsc
    arledgsc


    Posts : 494
    Join date : 2012-11-30
    Age : 70
    Location : Santa Rosa CA

    Upgrade VTA ST70 to ST120?  Empty Re: Upgrade VTA ST70 to ST120?

    Post by arledgsc Mon Feb 27, 2017 10:27 am

    I would be inclined to say not worth it unless you also change output transformers plus the 2nd choke to take advantage of the extra power capability of the ST120 power tranny.
    corndog71
    corndog71


    Posts : 840
    Join date : 2013-03-19
    Location : It can get windy here

    Upgrade VTA ST70 to ST120?  Empty Re: Upgrade VTA ST70 to ST120?

    Post by corndog71 Mon Feb 27, 2017 11:05 am

    Or you can try to sell your ST70 so someone else can enjoy it while you buy a new ST120.
    Peter W.
    Peter W.


    Posts : 1351
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Upgrade VTA ST70 to ST120?  Empty Re: Upgrade VTA ST70 to ST120?

    Post by Peter W. Mon Feb 27, 2017 11:26 am

    corndog71 wrote:Or you can try to sell your ST70 so someone else can enjoy it while you buy a new ST120.

    Best advice yet!
    polarflux
    polarflux


    Posts : 49
    Join date : 2010-02-12
    Location : Alaska

    Upgrade VTA ST70 to ST120?  Empty Re: Upgrade VTA ST70 to ST120?

    Post by polarflux Mon Feb 27, 2017 1:26 pm

    I was wondering if the output tranny's were different. For some reason I thought the st120 also used an a440, or whatever the vta st70 used. With that, yep, would be better to start fresh with a new build.
    Bob Latino
    Bob Latino
    Admin


    Posts : 3260
    Join date : 2008-11-26
    Location : Massachusetts

    Upgrade VTA ST70 to ST120?  Empty Re: Upgrade VTA ST70 to ST120?

    Post by Bob Latino Mon Feb 27, 2017 2:42 pm

    corndog71 wrote:Or you can try to sell your ST70 so someone else can enjoy it while you buy a new ST120.

    This is the best advice ... The three transformers are different and I do not sell the ST-120's transformers separate from the amp kit. If you can sell your (now wired) VTA ST-70, you may be able to get enough funds to purchase the KIT version of the ST-120.

    Bob

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    Upgrade VTA ST70 to ST120?  Empty Re: Upgrade VTA ST70 to ST120?

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