Got a lead on a Dynaco Dynakit ST-70 Stereo Tube amp

Discussion in 'Shock Brother's DIY Amps' started by peteb, Sep 22, 2019.

  1. Teleguy61

    Teleguy61 Friend of Leo's

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    This is a very high quality amp, and highly desirable in hi-fi circles.
    If you don't want it, sell it to someone who will use it for its intended purpose.
     
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  2. Paul G.

    Paul G. Friend of Leo's

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    It should be refurbished and used or sold. You haven't lived until you listened to vinyl through a quality tube amp. These are fine HiFi amps.
     
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  3. warrent

    warrent Friend of Leo's

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    Well whatever happens don't just let it go for $100. Paired with Quad 57 speakers that is the cornerstone of a nice audio system.
    Parts are here
    https://www.dynakitparts.com/
    The forum is here
    http://dynacotubeaudio.forumotion.com/

    The driver board is detailed here
    http://dynacotubeaudio.forumotion.com/t191-dynaco-st-70-pc-3-driver-board-parts-layout-photo

    Triode electronics also has parts and transformers But I haven't dealt with them in years so i don't know if they are still good.
    http://triodeelectronics.com/dynacoupgrades.html
     
  4. Dan R

    Dan R Friend of Leo's

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    David Hafler designed the Stereo 70 and offered it in built or kit form. It was a revolution in hi fi because it rivaled Marantz and McIntosh models of the day, which were much more expensive.

    Have you ever heard a Stereo 70 in a hi fi system? I have, it is so realistic it will blow your mind. A Stereo 70 with decent equipment sounds fantastic.
     
    Last edited: Sep 23, 2019
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  5. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    I picked up one of those several years ago at a yard sale for $10. I kept the Mullard tubes, and gave the chassis to an amp tech friend. He told me later that he sold it online for $100!
    That said I do have a Dynaco 2-EL34 amp that I used to use with my MP3 player for practice. It sounded great through an EV floor monitor. All that it needed to get it working was a plate resistor, I haven't used it in years though.
     
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  6. David Barnett

    David Barnett Doctor of Teleocity

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    That could be a MkII or MkIV.
     
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  7. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    MK IV I think! I has an odd PI tube, I see adapters advertised to convert it to something more common.
     
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  8. muscmp

    muscmp Tele-Afflicted

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    i have two st70s that i run in monoblock. great sounds!! it is best to leave it as is and not change to a guitar amp. too much to do and not worth it. run it thru a variac and bulb limiter to test and then clean it up and sell it if you are not going to do any restoration.

    play music!
     
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  9. David Barnett

    David Barnett Doctor of Teleocity

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    7199. It was very common in its day, but the world supply dried up pretty quickly when they went out of production. It was never a cheap tube, I remember them being $17.99 when a 12AX7A was $5.99.
     
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  10. DADGAD

    DADGAD Tele-Afflicted

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  11. Ricky D.

    Ricky D. Doctor of Teleocity

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    Peteb, I'll be so disappointed if you don't put that amp on your bench and use it to gain practical experience to support all your EE inquiries. Seriously, go for it. You'll end up with something worthwhile.
     
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  12. peteb

    peteb Friend of Leo's

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    the 7199 looks like a triode and a pentode in a single tube. I looked for them at the tube depot and they are $50 apiece.




    thanks Ricky. My first take on it was that I needed to make a guitar amp out of it. I picked it up and felt how heavy it was (the iron) and I really like the look of a tube amp with the tubes standing up. The fact that it turns out to be a well known hi fi amp makes me not want to re purpose it. and this



    the back story is that it is my mother in law's amp and other family members have been helping to clean out her home so that she can move and down size. I have the first claim, but im not the only one. I am going to let my second cousin in law, a teen ager who sells stuff online do what he wants with it.
     
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