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    Octal ST-70 driver and transformer

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    dougmon

    Posts : 65
    Join date : 2013-11-04
    Age : 59

    Octal ST-70 driver and transformer

    Post by dougmon on Fri Nov 29, 2013 5:46 am

    Hi all:

    I'm new to this board -- I joined basically because I have a wired VTA ST-70 on the way, and wanted to get more knowledge about it.

    However....the VTA ST-70 will be replacing a ~40-year-old Dynaco -- and I thought rather than selling the Dynaco off, I'd try my hand at doing a little cleanup and modification on it.

    So...what I'd like to do is install the tubes4hifi octal driver board. But from my reading, it's my understanding that the octal driver and the stock Dynaco power transformer are not well-matched, and that I'd need an upgraded power transformer.

    So my question is this -- where could I get an adequate power transformer? Would the PA060 from dynakitparts do it, or would I need something a bit beefier? One other question: are there any other things I should replace? I was thinking with a new power transformer, maybe a new multi-section capacitor too.

    Thanks in advance

    Doug

    Bob Latino
    Admin

    Posts : 2374
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Octal ST-70 driver and transformer

    Post by Bob Latino on Fri Nov 29, 2013 11:02 am

    Hi Doug,

     Yes - The PA-060 power transformer for the ST-70 from Dynakitparts is an upgraded power transformer with a higher stack and has greater power transfer capabilities. The POWER transformer on the original Dynaco ST-70 has a small 1 1/2 to 1 5/8 inch stack and tends to run warm just using the stock driver circuit with TWO 7199 driver tubes.

    Bob

    dougmon

    Posts : 65
    Join date : 2013-11-04
    Age : 59

    Re: Octal ST-70 driver and transformer

    Post by dougmon on Fri Nov 29, 2013 1:36 pm

    Thanks for the quick reply. I'm sure I'll be back in 3-4 months (when I'll be able to get started on it) with other questions like "what does this red wire do again?"

    I'm also going to replace the choke (because the old one sprayed that brown goo all over) and the multi-section capacitor (I dunno -- seems like a good idea if I'm replacing the power transformer).

    I'm pretty much a newbie as far as putting stuff together -- I'm going to do a few really simple projects first -- but if I've said anything here that sounds totally wrong, I certainly won't be offended if someone corrects me.

    Thanks.

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