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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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    non-polarized electrolytics

    j beede
    j beede


    Posts : 473
    Join date : 2011-02-07
    Location : California

    non-polarized electrolytics Empty non-polarized electrolytics

    Post by j beede Thu Feb 17, 2011 10:42 pm

    So what is the current thinking with respect to using polarized versus non-polarized electrolytics? In particular I am talking about the 50µF, 75V caps in the Mark III bias generator.
    ...j
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    GP49


    Posts : 792
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    non-polarized electrolytics Empty Re: non-polarized electrolytics

    Post by GP49 Fri Feb 18, 2011 1:00 pm

    There is no point in doing that. The bias circuit operates at constantly negative voltage. Barring malfunction it does not go positive, so conventional electrolytics work just fine (if one does not wire them with the negative side grounded -- a mistake I have seen more than a few hobbyists do).
    j beede
    j beede


    Posts : 473
    Join date : 2011-02-07
    Location : California

    non-polarized electrolytics Empty Re: non-polarized electrolytics

    Post by j beede Fri Feb 18, 2011 1:15 pm

    Yes. I didn't mean from an electrical necessity point of view, I meant from stability and reliability points of view. My local vendor's stock of 47µF, 100V caps are non-polarized and I have not used them before. I'll visit the Sprague web-site to get educated on NP electrolytics.
    ...j
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    GP49


    Posts : 792
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    non-polarized electrolytics Empty Re: non-polarized electrolytics

    Post by GP49 Sat Feb 19, 2011 1:05 am

    Your local vendor's nonpolarized electrolytics are likely meant for loudspeaker crossovers, which is an AC application requiring nonpolar capacitors. The DC power supplies in Dynaco amplifiers do not.

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