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    e80cc in center position on st-70

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    bozo

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    Join date : 2012-01-12

    e80cc in center position on st-70 Empty e80cc in center position on st-70

    Post by bozo on Sat Jan 14, 2012 12:24 pm

    Can this tube be used in this position
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    bozo

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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by bozo on Sun Jan 15, 2012 12:09 pm

    I have the 12au7 version of your st70 amp. I have several e80cc tubes that I used in another preamp without any issues. I use 3 12au7's and the amp works fine. I plugged the e80cc's into the middle position and got a crackling sound out of the right channel. It does the same thing with all 3 e80cc's I tried. Bias remains stable. Any ideas.
    danskman
    danskman

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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by danskman on Sat Jan 21, 2012 1:35 pm

    Mmmh... if the problem arises only on one channel, with any e80cc tubes you tried, I would check the tube socket contacts tension. The e80cc could have smaller pins than 12au7. Just my 2¢...
    Best regards,
    Danskman
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    bozo

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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by bozo on Sat Jan 21, 2012 3:20 pm

    I will check it. I can use the e80ccs on both the outside positions without a problem its only when I insert one of them in the center.
    danskman
    danskman

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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by danskman on Sat Jan 21, 2012 6:22 pm

    Yes, that's why I tought about the socket, especially the middle one.
    tubes4hifi
    tubes4hifi
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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by tubes4hifi on Sun Jan 22, 2012 12:06 am

    the E80CC is the same as a 6085 tube, it has about 50% more gain than a 12AU7, and more important, it uses double the filament current.
    mantha3
    mantha3

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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by mantha3 on Tue Jan 24, 2012 5:17 pm

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    spantou

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    Join date : 2019-03-19

    e80cc in center position on st-70 Empty Components for new build board with E80CC

    Post by spantou on Wed Mar 20, 2019 11:20 am

    I am preparing to build my new VTA-70 board and would like to use E80CC in the center position. I have the upgraded Power transformer, so the additional heater requirements should not be an issue.

    My question is what component values should be changed from the standard schematic to optimize the operating point for the E80CC.  I wondered if other VTA experts have experimented and came to conclusions since this very old thread started.
    tubes4hifi
    tubes4hifi
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    e80cc in center position on st-70 Empty Re: e80cc in center position on st-70

    Post by tubes4hifi on Wed Mar 20, 2019 12:51 pm

    I would try the following changes to use the E80CC tube in the center position only
    R5 & 6 150 ohm
    R9 & 10 1.5K
    R11 & 12 47K
    R13 & 14 68K
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    spantou

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    Join date : 2019-03-19

    e80cc in center position on st-70 Empty Thanks for the speedy reply.

    Post by spantou on Wed Mar 20, 2019 1:49 pm

    Will try those values and send followup if I have any comments.

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