Simple grounding question (separate power supply)

[sneakers563]

Please excuse this obviously silly question from a novice. I'd like to put the power supply for my gainclone in a separate chassis from the amp. Is there anything special to consider when hooking up the safety ground in order to avoid ground loops?

I imagine I connect the mains ground to the power supply chassis where it enters. I image I then run a wire from that ground through the umbilical to the amp chassis. Finally, I would think that I would attach that to the amp chassis, so that both chassis are connected to the safety ground.

However, because I've had it drilled into me that the ground should attach to the chassis in only one place, I can't get it out of my head that the chassis is attached to ground in two places, and therefore I'm leaving myself open to a ground loop. Or is that wrong, because the chassis aren't physically touching?:

[Joshua_G]

When there are 2 chassis, the ground of each would better be connected to only one point of each chassis. It's unsafe to have one chassis which isn't connected to the safety ground.

[Jen-B]

Originally Posted by sneakers563

I imagine I connect the mains ground to the power supply chassis where it enters. I image I then run a wire from that ground through the umbilical to the amp chassis. Finally, I would think that I would attach that to the amp chassis, so that both chassis are connected to the safety ground.

That's fine. So now you have your safety ground sorted.

So now all you have to do is sort your signal ground. My way would be to isolate all signal grounds from safety ground in your amp chassis and bring them to a star point. Then from that point run a thick wire back through the umbilical to the junction of the power supply capacitors in your power supply box.

Remember that when your power supply is distant you need some substantial power supply capacitors right at the amp power pins in the amp chassis. The ground side of these caps should go to the star point that I mentioned.

I know someone who has built one this way and it worked fine. Actually that's where I got the info from!

J.

[sneakers563]

Originally Posted by Jen-B

That's fine. So now you have your safety ground sorted.

So now all you have to do is sort your signal ground. My way would be to isolate all signal grounds from safety ground in your amp chassis and bring them to a star point. Then from that point run a thick wire back through the umbilical to the junction of the power supply capacitors in your power supply box.

Remember that when your power supply is distant you need some substantial power supply capacitors right at the amp power pins in the amp chassis. The ground side of these caps should go to the star point that I mentioned.

I know someone who has built one this way and it worked fine. Actually that's where I got the info from!

J.

Interesting - thanks! I wish there was some kind of tutorial out there for doing this. The kits from chipamp, audiosector, 41hz, etc. are great for building the amp, but there's not much out there in terms of chassis and finishing the amp.