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    Simple add ons that made a world of difference

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    LeGrace
    LeGrace

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    Simple add ons that made a world of difference

    Post by LeGrace on Tue Dec 11, 2018 8:46 pm

    First the back story. A few months in with my new M125's I was starting to think I had made a huge mistake. I already had lost 2 rectifiers and a power tube, and many times that in fuses. Plus experienced multiple red plates. To add insult to injury also was dealing with an annoying background hum issue. The red plates were definitely the worst though. I became paranoid to even leave the room for a few minutes. I was wondering, what is going on and why did I ever get into tubes?  

    Based on advice I measured this and that voltage, resistance and cap values, examined solder joints over and over with a magnifying glass, but just couldn't find anything off. I was even advised dude you need to ship those off to someone who knows tube gear to check them over, you obviously messed up the builds big time.  

    Except I hadn't. Two inexpensive add ons solved all my issues.

    First was a bucker transformer. Parts cost me about 50 bucks. No more blown tubes, fuses, or red plates. I can leave the amps on now for days on end, they just glow calmly. Problem was not build quality but rather an all too common one these days, excessive utility supply voltage. The bucker lowers it to a safe value.

    Second was even cheaper. Cheater plugs to float the grounds, costing a couple bucks apiece. Totally eliminated my hum issue, background is totally silent now.

    These two simple add ons added up to a world of difference. Feel free to share any others.
    WntrMute2
    WntrMute2

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    Re: Simple add ons that made a world of difference

    Post by WntrMute2 on Wed Dec 12, 2018 7:46 pm

    I think the bucking transformer is a great idea but floating the grounds is a DANGEROUS practice.  I had a bad ground loop hum as well with a pair of Radiotron 300B amps I built and floating the grounds fixed the hum.  Once I knew it was a ground loop I plugged both amps into a single power strip and the hum was gone but the ground protection remained intact.
    I then bought one of those six foot long power strips available an most good hardware stores and plugged all the signal carrying equipment into that.  My Mono-blocks, pre-amp, phono-stage, CD player and tuner are all on one circuit and my TT drive, system lights and accessory equipment into another circuit.  All is deathly quiet now.  
    Please don't defeat your safety ground.  I understand it gets rid of the ground loop but there are ways to silence the hum as well as maintain safety.
    erhard-audio
    erhard-audio

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    Re: Simple add ons that made a world of difference

    Post by erhard-audio on Wed Dec 12, 2018 8:59 pm

    I have to 100% agree. The ground wire is there for a VERY good reason and should never be removed or disconnected in any way.
    All ground loops can be fixed without having to disconnect the safety ground to the gear.
    All my gear uses three way power cords and every chassis/metal plate is connected to house ground and I have never had any issues with ground loops.
    Do make the effort to remedy your issue without disconnecting house/safety ground!
    Peter W.
    Peter W.

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    Re: Simple add ons that made a world of difference

    Post by Peter W. on Thu Dec 13, 2018 8:44 am

    Well... Much of ground loops is because at the typical outlet, it is often the case that the ground and the neutral are at different potentials. It should not be, but all-too-often it is.

    a) Audio systems should all (repeat: ALL) be plugged into a single receptacle.
    b) That receptacle should be a dedicated line directly to the panel.
    c) That receptacle should be fed with (minimum) 12 gauge wire, with all three conductors - hot/neutral/ground - the same gauge.
    d) Ideally, the neutral and the ground should be connected, alone, to adjacent points on the ground buss in the panel.
    e) and, an accurate DVM should read *exactly* the same voltage hot-to-ground and hot-to-neutral.

    One more note: Do not use the push-connectors on the receptacle. Get a properly-rated 20 A receptacle and use the screw connectors. Tighten them well!
    Bob Latino
    Bob Latino
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    Re: Simple add ons that made a world of difference

    Post by Bob Latino on Thu Dec 13, 2018 12:49 pm

    LeGrace wrote:Cheater plugs to float the grounds, costing a couple bucks apiece. Totally eliminated my hum issue, background is totally silent now.

    This is a common cause of hum in tube amps IF your amp has a 3 wire cord AND one other component in your music system ALSO has a 3 wire cord. You get a "ground loop". The solution is what Legrace has mentioned. Use a 3 to 2 wire ""cheater plug" on one or both components and your hum should go away. Check out the Youtube video below on ground loops

    Bob


    erhard-audio
    erhard-audio

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    Re: Simple add ons that made a world of difference

    Post by erhard-audio on Thu Dec 13, 2018 1:22 pm

    Bob Latino wrote:
    LeGrace wrote:Cheater plugs to float the grounds, costing a couple bucks apiece. Totally eliminated my hum issue, background is totally silent now.

    This is a common cause of hum in tube amps IF your amp has a 3 wire cord AND one other component in your music system ALSO has a 3 wire cord. You get a "ground loop". The solution is what Legrace has mentioned. Use a 3 to 2 wire ""cheater plug" on one or both components and your hum should go away. Check out the Youtube video below on ground loops

    Bob



    this is one of those subjects where we need to agree to disagree Wink
    Removing the safety ground is a 100% no-no in my books. Doing so in order to solve a ground loop issue is the 'easy' and dangerous way out.
    Every ground loop issue can be solved without resorting to disconnecting the ground. Sure, you'd probably get away with doing so in 99% of cases....but its that 1% that can really hurt you, or worse, and that 1% is enough reason for me to not disconnect the safety ground.
    And as Forest Gump said...that's all I have to say about that....
    Peter W.
    Peter W.

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    Re: Simple add ons that made a world of difference

    Post by Peter W. on Thu Dec 13, 2018 2:17 pm

    The key, ladies & gentlemen, and children of all ages is to have every component at the same potential, internally and externally. And why it is that star-grounding systems are generally preferred. We are lucky to live in a house with a two-pipe radiator system installed in 1928 (sized for gravity!) So I have excellent grounding options in every room.

    https://images.homedepot-static.com/productImages/7f2e95f8-7edc-44ec-a87c-f888ebc102fb/svn/blackburn-conduit-fittings-j-b1-25-64_1000.jpg to a supply pipe, and I am humless.
    tubes4hifi
    tubes4hifi
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    Re: Simple add ons that made a world of difference

    Post by tubes4hifi on Sun Dec 16, 2018 10:03 pm

    and I've been saying for years, plug ALL of your stereo equipment into ONE strip plug, then they will all have a common ground
    Peter W.
    Peter W.

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    Re: Simple add ons that made a world of difference

    Post by Peter W. on Mon Dec 17, 2018 1:39 pm

    tubes4hifi wrote:and I've been saying for years, plug ALL of your stereo equipment into ONE strip plug, then they will all have a common ground

    Agreed. But PLEASE do verify that the Ground and the Neutral are at the same potential. Sadly, and very nearly as often as not, they are not.

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