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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


4 posters

    [ST-70] EL-34

    Nicola
    Nicola


    Posts : 12
    Join date : 2011-11-20
    Location : Roma (Italy)

    [ST-70] EL-34 Empty [ST-70] EL-34

    Post by Nicola Wed Feb 15, 2012 5:20 pm

    Hi everyone!
    My fully original Stereo 70 has a bad EL34 tube. It still has these four '60 Philips Miniwatt:

    [ST-70] EL-34 Philipsminiwattsmall

    I've only a couple of questions:

    1) I would like to replace the bad tube only. Is it a big heresy, to use the amplifier with 3 vintage tubes and one new and from a different brand?

    2) I can easily find EL34s from JJ-Electronics and Electro-Harmonix. Which one do you think is the better one, in my situation?

    Thank you in advance Very Happy
    Luddite
    Luddite


    Posts : 233
    Join date : 2009-02-04
    Age : 73
    Location : Texas

    [ST-70] EL-34 Empty Re: [ST-70] EL-34

    Post by Luddite Wed Feb 15, 2012 5:55 pm

    Nicola wrote:Hi everyone!
    My fully original Stereo 70 has a bad EL34 tube. It still has these four '60 Philips Miniwatt:


    I've only a couple of questions:

    1) I would like to replace the bad tube only. Is it a big heresy, to use the amplifier with 3 vintage tubes and one new and from a different brand?

    2) I can easily find EL34s from JJ-Electronics and Electro-Harmonix. Which one do you think is the better one, in my situation?

    Thank you in advance Very Happy

    With the original circuitry, you need to have both tubes on one channel closely matched. At the very least, I would replace with a matched pair, but it would be better to replace all four with a matched quad of the same brand tubes.

    Best Regards,
    Charlie
    Blitzen
    Blitzen


    Posts : 63
    Join date : 2009-07-10

    [ST-70] EL-34 Empty Re: [ST-70] EL-34

    Post by Blitzen Wed Feb 15, 2012 11:24 pm

    On the plus side, the three remaining tubes still have value if they're in good condition. I'm pretty sure those are actually Mullard tubes, which have a pretty high standing among the guitar amp crowd. If two of them still match up, they can be sold for probably close to what a new set of 4 costs...!
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    Guest
    Guest


    [ST-70] EL-34 Empty Re: [ST-70] EL-34

    Post by Guest Thu Feb 16, 2012 12:42 am

    .


    Last edited by PeterCapo on Wed Dec 02, 2020 1:41 pm; edited 1 time in total
    Nicola
    Nicola


    Posts : 12
    Join date : 2011-11-20
    Location : Roma (Italy)

    [ST-70] EL-34 Empty Re: [ST-70] EL-34

    Post by Nicola Thu Feb 16, 2012 6:34 am

    Thanks everyone!

    PeterCapo wrote:Are you sure one of the tubes has gone bad? Did you put it on a tube tester?
    I have a problem, described months ago in this topic: https://dynacotubeaudio.forumotion.com/t1018-st-70-noise-when-heating-up
    Conclusion was that there is one bad tube.
    Unfortunately I can't test tubes; actually I'm even not sure to have on each channel the same original matched pairs of tubes, because I moved them to figure out which one was bad. Last, I'm in Italy and I wouldn't like to ship my tubes far away, and waiting a lot of time.

    Even if I would like to take my ST-70 as original as possible, I think I'll get four new matched tubes so I'll be sure they'll be properly matched.

    Any suggestions about the tube brand? I've found Electro-Harmonix, JJ and even Bugera (I've never heard about it).

    Another time, thank you for your quick and expert suggestions!
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    Guest
    Guest


    [ST-70] EL-34 Empty Re: [ST-70] EL-34

    Post by Guest Thu Feb 16, 2012 1:07 pm

    .


    Last edited by PeterCapo on Wed Dec 02, 2020 1:42 pm; edited 1 time in total
    HiGHFLYiN9
    HiGHFLYiN9


    Posts : 8
    Join date : 2011-08-17
    Location : East Coast

    [ST-70] EL-34 Empty Re: [ST-70] EL-34

    Post by HiGHFLYiN9 Thu Feb 16, 2012 4:48 pm

    I'm very happy with the SEC Winged C, they have a warm and lush sound with a buttery smooth midrange.

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    [ST-70] EL-34 Empty Re: [ST-70] EL-34

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