The Dynaco Tube Audio Forum

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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

    Mark III on steroids!!

    denny9167
    denny9167


    Posts : 151
    Join date : 2011-05-09
    Age : 56
    Location : Texas

    Mark III on steroids!! Empty Mark III on steroids!!

    Post by denny9167 Thu Aug 13, 2015 3:17 pm

    Haven't posted in awhile, hope everyone is doing well. I was privileged to own a pair of Mark IV amplifiers for a year or two and I became a tube addict!! Is there a tube-o-holics anonymous out there? If there was I would need to go! Well I sold the custom pair of Mark IV's that I had built, and decided to graduate up to something a little more grand, possibly the Mark III's, but I was thinking since the Mark IV's are basically the ST-70 on steroids!! I would need to build a pair of Mark III's on Steroids, so my idea is this, fully regulated front end B+, DC heaters to the front end, and a beefier power supply. Have the power supply PCB ready to go, and main board, just need a chassis now to house it in. Any thoughts?
    j beede
    j beede


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

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    Post by j beede Thu Aug 13, 2015 10:07 pm

    I am a fan of the MkIII. I don't think the power supply has any serious weakness other than the quad cap's marginal working voltage. I replaced the quad cap with an array of series pairs of modern (compact) 450WVDC caps with balancing resistors. This enables solid state rectification and higher B+ when running KT-88 etc.

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    GP49


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

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    Post by GP49 Sat Aug 15, 2015 2:15 am

    Good comment about modern capacitors. The era of the plasma big-screen TV has come and gone, but with it came renewed production of large electrolytic capacitors of 350-450 volt ratings, easily adapted, as J Beede described, to tube amplifier power supplies...if you have the space available.
    sKiZo
    sKiZo


    Posts : 1530
    Join date : 2013-04-01
    Location : Michigan USA

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    Post by sKiZo Sat Aug 15, 2015 1:20 pm

    The era of the plasma big-screen TV has come and gone, but with it came renewed production of large electrolytic capacitors of 350-450 volt ratings

    Can I take that as a "get em while they're hot" kinda thang? Wonder just how long they'll still be available as a major application slides into history ...
    denny9167
    denny9167


    Posts : 151
    Join date : 2011-05-09
    Age : 56
    Location : Texas

    Mark III on steroids!! Empty Re: Mark III on steroids!!

    Post by denny9167 Sat Aug 15, 2015 3:32 pm

    sKiZo wrote:The era of the plasma big-screen TV has come and gone, but with it came renewed production of large electrolytic capacitors of 350-450 volt ratings

    Can I take that as a "get em while they're hot" kinda thang? Wonder just how long they'll still be available as a major application slides into history ...

    Hopefully as the interest in tube audio continues to grow, the demand for high-voltage electrolytics will also continue!

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