Trying to get this ground thing

[Randall]

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?

[xtian]

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.

This is fine. It is a good idea to ground to a bolt attached to the chassis.

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.

This is the benefit of building a production model. You get to try again and again, see what works best, and what's just good enough, and you end up with a nice quiet design that may or may not obey all the best practices!

[Super_Reverb]

There are many grounds schemes out there. My last build used a 12guage copper wire for preamp/pots/input jack ground. That ground, together with output cathodes, speaker gnd, reservoir gnd caps, screen caps, and PT center taps are connected to a centrally located chassis bolt. I solder lugs to each ground wire and bolt them down tight with washers in between and a locknut (OCD? maybe)

IMO, it is important to connect input jack to preamp ground, isolated from chassis (Marshall syle Cliff or other).

A good ground methodology is more than building one amp that has low noise. A good grounding methodology includes a technical understanding of your scheme and the pitfalls it avoids, such as ground loops, filter cap current in pre-amp etc. If you don't understand how and why your ground scheme works, you won't be able to troubleshoot your builds when it *doesn't* work. Not meaning to lecture here, but grounding is key to tube amps and all analog circuits in general.

Merlin Blencowe has a good description of his methodology here:

http://www.valvewizard.co.uk/Grounding.pdf

cheers, rob