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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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    Build ST35 with 6V6 rather than EL84?

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    len42


    Posts : 1
    Join date : 2021-10-28

    Build ST35 with 6V6 rather than EL84? Empty Build ST35 with 6V6 rather than EL84?

    Post by len42 Thu Oct 28, 2021 2:31 pm

    I have PA-774 and Z-565 iron for a DIY ST35 build. I want to use transformer covers (for looks) and am a bit concerned about heat in the power transformer. One thought was to swap out EL84s for 6V6s, which would drop the heater load for 4 tubes by 840mA. What I read seems to say that these tubes perform identically, but the EL84 took over because it was more compact. Does this change seem wise? I plan on using the Gillespie EFB. Would I need to do anything beyond changing the bias point for the 6V6s?
    peterh
    peterh


    Posts : 1599
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Build ST35 with 6V6 rather than EL84? Empty Re: Build ST35 with 6V6 rather than EL84?

    Post by peterh Fri Oct 29, 2021 1:52 am

    len42 wrote:I have PA-774 and Z-565 iron for a DIY ST35 build. I want to use transformer covers (for looks) and am a bit concerned about heat in the power transformer. One thought was to swap out EL84s for 6V6s, which would drop the heater load for 4 tubes by 840mA. What I read seems to say that these tubes perform identically, but the EL84 took over because it was more compact. Does this change seem wise? I plan on using the Gillespie EFB. Would I need to do anything beyond changing the bias point for the 6V6s?
    6V6 is not identical to EL84. And power usage for ST35 & PA774 is no problem. Thus there is
    ( in my opinion) no reason to depart from ST35 "standard".


    Last edited by peterh on Fri Oct 29, 2021 1:53 am; edited 1 time in total (Reason for editing : spelling)

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    corndog71
    corndog71


    Posts : 807
    Join date : 2013-03-19
    Location : It can get windy here

    Build ST35 with 6V6 rather than EL84? Empty Re: Build ST35 with 6V6 rather than EL84?

    Post by corndog71 Fri Oct 29, 2021 9:41 pm

    I’m with Peter and second his recommendation.  Stick with the known circuit. Also, the power transformer is going to get hot. That’s just the nature of tube amps. You could always drill vent holes into the cover.

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    Build ST35 with 6V6 rather than EL84? Empty Re: Build ST35 with 6V6 rather than EL84?

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