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    Mark III on steroids!!

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    denny9167

    Posts : 152
    Join date : 2011-05-09
    Age : 49
    Location : Texas

    Mark III on steroids!!

    Post by denny9167 on 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

    Posts : 328
    Join date : 2011-02-07
    Location : California

    Re: Mark III on steroids!!

    Post by j beede on 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.


    GP49

    Posts : 735
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: Mark III on steroids!!

    Post by GP49 on 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

    Posts : 1310
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Mark III on steroids!!

    Post by sKiZo on 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

    Posts : 152
    Join date : 2011-05-09
    Age : 49
    Location : Texas

    Re: Mark III on steroids!!

    Post by denny9167 on 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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