Tube amp grounding

[BobbyS]

I am asking this out of curiosity as I know the horse is well beaten.

I am curious: doesn't the amp grounding system, shown on the site, create a ground loop at the pots and chassis?

[tubenit]

I don't know if there are grounding loops or not? 

Having said that, I have used this on over 20 different amp layouts/topologies and always end up with a very quiet amp at idle.

Anytime, that I initially had some hum, ....... it had nothing to do with the grounding scheme.

This grounding scheme has worked for me 100% of the time to my satisfaction. 

With respect, Tubenit

[Willabe]

It could if the pot grounds were soldered to the back of the pots, but I don't think they are.

The buss wire on the back of the pots is just for the pots case. If you depend on just the pots star washer to make contact with the chassis to ground,(ie, using the case for shielding the resistive element in side the pot) after time the star washer/chassis connection can corrode and you will lose the pots case shielding.


           Brad        

[Willabe]

I take part of that back.

To me the main thing is Doug has the heaviest current (plate/OTCT, cathodes, plate and screen filter caps) in the amp grounded together at 1 point and the rest at another. That way the heavy output ground currents won't modulate the preamp ground currents.

So you could wire the pot grounds to the buss wire on the back of the pots with out any problems.

Now if you were to connect the output ground star with the preamp ground buss and you were using the pot buss wire for the pot grounds you would have a ground loop. (See red line in drawing below.)


              Brad        

[BobbyS]

Yeah I used it too and my 6G2 is quiet. As I was doing it though, that thought stayed in my head. So, I just thought I would ask.

Thanks!