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    VTA St70 with 6l6gc

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    tomerte

    Posts : 9
    Join date : 2015-04-25

    VTA St70 with 6l6gc

    Post by tomerte on Sat Mar 12, 2016 8:52 am

    Hallo together,
    I have an VTA St70 and like it very much.
    It is with SS rectifier, 6GU7 as input tube and 6CG7 as splitter tubes.
    The power tubes are EL34.

    Now I want to try the 6L6GC tubes. I have read, this is not a problem, it will work.
    But if I would like to get the best conditions for the 6L6GC, what would I have to change?
    Bias setting is enough?


    Enjoy your weekend
    Tomerte

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: VTA St70 with 6l6gc

    Post by tubes4hifi on Sun Mar 13, 2016 5:57 pm

    keep the bias at 40ma or better 35ma, and make sure not to use GB or GA tubes only rated at 360v
    6L6GC are rated at 450v.

    tomerte

    Posts : 9
    Join date : 2015-04-25

    Re: VTA St70 with 6l6gc

    Post by tomerte on Mon Mar 14, 2016 4:33 am

    Yes, I have read all the post here in the forum concerning the rolling of el34, 6l6cg and 6p3s-e.
    With the correct bias it will work. But the conditions for the 6p3s-e would not be ideal.
    What must I do, if I would like to get ideal conditions for the 6p3s-e?

    Thanks
    Tomerte


    erlingt

    Posts : 15
    Join date : 2010-06-23
    Location : Denmark

    Re: VTA St70 with 6l6gc

    Post by erlingt on Mon Mar 14, 2016 8:41 am

    If you set the bias to 35-40 mA the 6p3s-e works perfectly.
    I've been using a set in my ST70 for the last couple of years, and they now have run for more than 2.000 hours without any problems, and the bias is still steady.

    tomerte

    Posts : 9
    Join date : 2015-04-25

    Re: VTA St70 with 6l6gc

    Post by tomerte on Mon Mar 14, 2016 9:26 am

    Hallo erlingt

    Thank you for answering.
    I will do so, 35-40 mA. Some people are telling you can do till 50mA.

    If I make 40mA, than I have the same conditions as for EL34.
    But it is another tube the 6p3s-e!!!!
    For the best conditions for this tube, I think, it must be done some more.
    F.e. some resistors with less or more value? The value of the outputtransformer?
    Or to change the voltage of the plate?

    I am sure it will run without big changes. But perhaps it would sound still better
    and the tubes will live longer with the correct conditions for this tube.

    Nowhere in the net I found an answer, and i am not able to calculate this.


    Greetings to Denmark
    I am from Berlin, Germany

    Tomerte




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