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
Hi Sean,

Actually when I said, "salt" I did not mean it that way I should have said electrochemical. The company that I have found that does this stuff grounds substations, towers and the like. Their system has a lifetime of fifty years and only requires a little ground moisture to work effectively. Of course this come at a price, but this is the real thing. Check out http://www.sgscorp.com/index.html for more info.

- Dan
OK this is starting to drive me batty.
Today's events included changing the main system ground. We also tried all combos of grounding rods including none except for the main system ground, 2 supplemental rods tied together, all on one supplemental rod...you name it I think we have tried it. we also went through the whoel house flipping each circuit on sequentially but no single breaker added to the buzz effect. It seems to happen after the preamp and teh digital end are tirned on. It is there when only the preamp is on and is slightly greater wheen the digital end is turned on. I am actually starting to wonder if my cables are a problem . They are MIT and are singled ended. Still moving the cables around has no effect.
i notice that cheating the amps takes away teh buzz leaving a small hiss. Maybe this is noise coming in on the neutral?
When you tie the grounds together does that just mean passing a copper wire between them? Does anyone have anyo other ideas?
JD
Maybe you should take the preamp to a friends house and see if it does the same thing.... - Dan
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.