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    Dual Rectifiers

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    wgallupe

    Posts : 100
    Join date : 2014-05-18
    Age : 63
    Location : Central Mass.

    Dual Rectifiers

    Post by wgallupe on Thu Nov 10, 2016 3:07 pm

    Hi all,

    I'm in the planning stage of my Mark III build using the VTA/Dynakit kit from Roy M. One difference is that each monoblock will use a custom wood chassis with a top plate from Front Panel Express. This allows me to be creative with tube positioning and cosmetics. With the extra space available, I have had the idea of using two GZ34 rectifiers instead of the normal one.

    I'm hoping it will be as easy as running jumper wires from the pins on the first tube socket over to the second socket. Any thoughts or recommendations would be appreciated.

    Thanks,
    Wayne

    stewdan

    Posts : 163
    Join date : 2010-03-07
    Age : 78
    Location : Houston Texas

    Re: Dual Rectifiers

    Post by stewdan on Thu Nov 10, 2016 3:58 pm

    Hi --- using 2 GZ34's means that they are hooked up in parallel.  So you would run wires from the pins of the original socket to the corresponding pins of the second socket.  Stew

    wgallupe

    Posts : 100
    Join date : 2014-05-18
    Age : 63
    Location : Central Mass.

    Re: Dual Rectifiers

    Post by wgallupe on Thu Nov 10, 2016 6:48 pm

    It just occurred to me that the power transformer may not be able to deal with the extra current draw???

    Bob Latino
    Admin

    Posts : 2454
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Dual Rectifiers

    Post by Bob Latino on Thu Nov 10, 2016 7:18 pm

    Just my opinion but > You don't really need TWO 5AR4/GZ34 tube rectifiers for EACH Mark III build. A 5AR4 is good for 225 milliamps of current flow for the B+ high voltage system. Two KT88's biased at 50 milliamps is 100 milliamps. Two 12AU7's on the VTA Mark III board use about 8 to 10 milliamps each.... Each Mark III won't draw more than 125 milliamps for the B+. This is well below the ability of a 5AR4/GZ34 tube rectifier to provide current ..

    Bob

    deepee99

    Posts : 1384
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Dual Rectifiers

    Post by deepee99 on Fri Nov 11, 2016 6:12 am

    I found doubling-up on rectifiers in parallel to be of no benefit in the M-125s, just IMHO. Just more current pull for the heaters. God bless the Mullard GZ-33 and-37s. I will begin re-attending church should someone build an honest GZ-33 in future.

    peterh

    Posts : 735
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Dual Rectifiers

    Post by peterh on Fri Nov 11, 2016 8:40 am

    wgallupe wrote:Hi all,

    I'm in the planning stage of my Mark III build using the VTA/Dynakit kit from Roy M. One difference is that each monoblock will use a custom wood chassis with a top plate from Front Panel Express. This allows me to be creative with tube positioning and cosmetics. With the extra space available, I have had the idea of using two GZ34 rectifiers instead of the normal one.

    I'm hoping it will be as easy as running jumper wires from the pins on the first tube socket over to the second socket. Any thoughts or recommendations would be appreciated.

    Thanks,
    Wayne  
    This might not be a good idea. Both tubes will see the full voltage, transformer will
    be harder loaded, and your reliability will be effectively halved ( as the probability for
    at least one tube fails will double).
    Better to use zero gz34 ( use 2 1n4007 in series for a total of 4 ) for reliability .

    wgallupe

    Posts : 100
    Join date : 2014-05-18
    Age : 63
    Location : Central Mass.

    Re: Dual Rectifiers

    Post by wgallupe on Fri Nov 11, 2016 8:51 am

    Guys, Thanks for the advice. I'll stick to the one tube rectifier per original MK3 specs. The idea started because I found some info on line that suggests today's new production GZ34 do not last long in the MK3. I guess I'll continue to hunt GZ33/GZ37 rectifiers and keep a few WZ68 as back-up.

    Wayne

    deepee99

    Posts : 1384
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Dual Rectifiers

    Post by deepee99 on Fri Nov 11, 2016 10:38 am

    Wayne,
    Don't diss the Webers; they talk and walk like a real rectifier tube. And like tubes, they are consumables but a heck of a lot cheaper than a Mullard. If you've got a large stash of original Mullard GZ-33s, please PM me your street address and the hours you are not at home. lol!

    wgallupe

    Posts : 100
    Join date : 2014-05-18
    Age : 63
    Location : Central Mass.

    Re: Dual Rectifiers

    Post by wgallupe on Fri Nov 11, 2016 10:52 am

    Hi Dave, I agree. I know the Webbers are OK. They sound fine, in fact really good in my ST120 (that is now sold). I think I will use the Webbers for everyday listening and, as you stated so elegantly in an older thread, 'I put in the Mullards when royalty visits'.... Made me laugh when I read it and never forgot it Laughing

    I only have 2 GZ37s and 1 GZ33 all used. A long trip for you to make for such a small score!

    deepee99

    Posts : 1384
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Dual Rectifiers

    Post by deepee99 on Fri Nov 11, 2016 11:03 am

    Wayne, I have frequent flyer miles. Your address, again?

    Tube Nube

    Posts : 657
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Dual Rectifiers

    Post by Tube Nube on Fri Nov 11, 2016 3:34 pm

    Was jt the movie Cannon Ball Run where someone landed on main street of some small town in a Maule? Just a thought--I suffer from a bit of Mullard envy myself.

    sKiZo

    Posts : 1337
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Dual Rectifiers

    Post by sKiZo on Fri Nov 11, 2016 8:14 pm

    neener neener ... clown



    And I bought two so I got a spare ... pig pig

    NOS Canadian military surplus ... they sold out fast.

    deepee99

    Posts : 1384
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Dual Rectifiers

    Post by deepee99 on Fri Nov 11, 2016 8:30 pm

    Arsle.

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