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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


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    Operating voltage for output section of ST-70

    SuperB
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    SuperB


    Posts : 15
    Join date : 2012-01-01
    • Post n°1

    Operating voltage for output section of ST-70 Empty Operating voltage for output section of ST-70

    Post by SuperB Mon Jan 02, 2012 2:25 pm

    Hey!
    Since I want to separate the power supply for driver and output section on the ST-70. And I want to run 440V on the output tubes (EL34), what is the operating current should I settle for 440V.

    Also, I want to put a OPT with 5K primary to replace the A470. What is circuit change require?

    Thanks!
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    Roy Mottram
    Roy Mottram
    Roy Mottram
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    Posts : 1839
    Join date : 2008-11-30
    • Post n°2

    Operating voltage for output section of ST-70 Empty Re: Operating voltage for output section of ST-70

    Post by Roy Mottram Mon Jan 02, 2012 3:23 pm

    if you allow 50ma of current for each EL34 output tube, then you'll need a total current of 200ma.
    you shouldn't need any changes for the output transformers, other than possibly fine-tuning the negative feedback capacitor value.
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