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buzzzzz, where did i go wrong?

The setup:
spectral monoblock amps
spectral preamp
theta front end

The NEW DEDICATED CIRCIUTS
4 separate circuits each with fuses jumped off the main box and grounded to the main box
one circuit for each monoblock
one for the preamp
one for the digital front end (MIT power conditioning)

the amps and preamp each share a supplemental grounding rod. The digital end has its own supplemental ground rod
The outlets are all FIM880. These do not have an isolated ground (could that be the problem?)

I still have a buzz.low but audible; it goes away when I lift the ground from my amps. I assume I have a ground loop but I am not sure how or what I do about it. I assume I have made some awful basic error but not sure how.
I know for instance from the posts that Garfish uses three supplemental grounding rods. Maybe I should have tied all those together? any other ideas
jdwek
dan2112
144 posts
 
Maybe you should take the preamp to a friends house and see if it does the same thing.... - Dan
sean
6,231 posts
 
JD, drop me an email at your convenience. Sean
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mar00
59 posts
 
I've done similar circuit and grounding uprades.The key as others have mentioned is your using the new rods to supplement your existing service ground lowering the overall resistance.Spacing of the rods is important,they should be at least six feet from the service ground and six feet apart and each rod must be tied back(with a separate wire) to the same point in your panel as the service ground.Don't tie the rods together as you want the rods connected in parallel not series.Also you should have an isolated ground on your outlets for each circuit and each ground wire should be connected back to the same point in your panel as your service ground and rods.This is the essence of a star grounded system with ONE low resitance pathway to earth.If your using your fuse connections as a subpanel in some kind of enclosure make sure none of your neutrals are bonded to it.If your using in-line fuses you won't have this concern.
jdwek OP
84 posts
 
Sean,
I mailed you but I don't think you got it. I think there is a problem. Could you mail me?
Thanks
JD
jdwek OP
84 posts
 
Ok I think I am getting it. Let me be more specific. The panel and the two rods are separated by about 35 feet. The two rods are about 6 feet from each other. I am going to take one copper wire from each rod to the grounding bar in the main box.
The outlets are still FIM880's which do not have an isolated ground. The conduit is their ground. Should I also use their copper grounding wire and land it to the grounding bar?
About the fuses, they indeed are a subpanel but i am not sure what is meant by the neutrals being bonded to it or not. By the way...I do own a multimeter and I not afraid to use it!....maybe someone could tell me how?
Thanks JD
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