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Trying to get past this grounding thing

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  • Trying to get past this grounding thing

    I am nearing completion on my first 5E3 build. The one thing holding me up is the grounding scheme. I've read a lot of opinions here and elsewhere about separating input and output grounds in various ways. I decided to go with separating the filter cap grounds and running separate ground wires from B+ filter, screen supply filter, and output cathode to a PT stud. This is also where power and filament CTs are connected. Then I thought i would try running the pre-amp plate filter over to the pre-amp ground bus, which I had intended to employ the copper wire trick, and connect the pre cathodes and pots to it. Trouble is I don't see the best way to accomplish this. I think I understand this bus gets grounded close to the input jacks, and it seems like the easiest way would be to connect to one of the open ground lugs on a jack. But jacks get loose, and since it would now be supporting plate and cathode grounds, that just doesn't seem like a good idea to me.

    And I'm not sure I'm liking the copper wire bus as much as I once did. Seems a bit clunky and wobbly, which also seems like a good place for failure should it move too much. So I wonder about running separate solid core ground wires all to the same point and maybe drill a new hole close to the inputs and ground there.

    And then I got a close look at a $2,000 Clark Beaufort and as far as I could tell he just soldered grounds straight to frame right where they stood just like the original, and that amp sounds great.

    What says you?
    Last edited by Randall; 02-16-2013, 11:23 PM. Reason: can'y type
    It's weird, because it WAS working fine.....

  • #2
    People build great sounding 5E3's using the old brass grounding plate all the time (including Clark). Others have no problem with the simple ground bus to the input side of the chassis, running the last ground wire (main filter cap, cathode bias resistor/cap) to the PT bolt. The 5E3 is pretty simple and forgiving. Either should work fine, I wouldn't but too much effort or money into anything more complex.

    I run the Ground Bus, connecting it to the chassis near the inputs. The Ground Bus is held in place by tension from the eyelet board grounds on one side and grounds from the pots on the other (I don't ground to the backs of the pots). The first filter cap and cathode bias ground go to the PT bolt closest to them. And I run the CT to a different bolt.

    Don't overthink this and lose time, parts and money trying to be exact, it's an easy amp to build right.
    Last edited by wyatt; 02-16-2013, 07:15 PM.


    • #3
      I'm not a 5E3 builder.
      It looks like everyone just grounds everything.
      Here is a Layout, with some separation.
      I would just look and see how all the kit places does it.
      I like how Marshall kits do it with the buss wire off the board.
      All the amps I've built do it that way.
      Here, you can compare the two different ways.

      "If Wishes Were Horses, Beggars Would Ride!" Scottish Proverb 1600s