tips for dealing with hums/buzzing amps due to RFI?

[joninc]

i am just starting to move gear into my new space (detached workshop on our property) and noticing some buzzy/hummy sounds from amps. The shop has it's own new 40A service and dedicated ground plate and was all done up to code and properly.

the power (voltage) looks to be coming out of the outlets at about 121.

it's not just one amp/guitar/cable - it seems to be not even from the AC but it's hard to tell. if you disconnect the patch chord from the amp, no more hum or buzz - so it would appear to be some type of interference being picked up by the guitar pickups. (tried on different types of guitars with diff pickups and bass too). take your fingers off the strings and it's BUZZZZZ.

we are in the country on an acreage.

what can i do to begin to address this problem?

[norton]

40 amps isn't a huge amount of power. Is it a sub panel being fed off a main panel?

Where does that line run? Is it prone to picking up any interference itself?

Is there a water line in the shed?

From what I understand the ground wire connected to copper is much more effective than the rod in the ground.....perhaps a more robust ground will be helpful?

[Snarl 12/8]

What sources of RF are nearby? Motors, AC, Fridge, computers, florescent lighting, etc., etc. If it was me, one thing I might try is shutting off everything except that one 40 amp panel and see if the problem goes away. If it does, then you bring things back one circuit at a time until you find the culprit. If it doesn't, then disconnect everything from the 40 amp panel and add it back one by one until you find your culprit.

[joninc]

sorry - it's a 60A panel.

There's nothing nearby. That's what is so weird. It's LED track lighting. Yes there are dimmers but turning them off makes no difference.

I wonder if I need some sort of power conditioner?

I'll try turning off the breakers 1 at a time and see if anything helps.

[Snarl 12/8]

Does this 60A panel have its own service out to the street or is it a subpanel from somewhere else. If the latter, you've got to look at everything plugged into that panel too. Have you called the electrician back who did it and showed them the problem? There might be different ways they could ground it or isolate it and they picked the wrong one for your situation.

[joninc]

it's a subpanel from the house.

It has it's own dedicated ground.

To the average user - there is no problem so I don't think I can get the electrician to "fix" anything. I have a tech who may be able to look at the power on a scope to get a more detailed picture of the power but this is beyond the scope of any of the electricians I have spoken to.

But for a studio, the needs are quite different. There's plenty of voltage coming through - i just need CLEAN power without any high end hash or distortions.

I guess I am wondering if anyone knows of ways to make the power coming off my subpanel "cleaner".

[goose134]

I can tell you with some degree of certainty that if the neutral that is powering your panel has originated from the main panel, then your neutral is tied to everyone else's neutral on the block. This ALWAYS leads to circulating neutral current on the ground (which is bonded to the neutral). This is because the main source of grounding electrodes is the water mains, which is feeding everyone's house who has water. Any electrical noise generated on the system will transfer to some degree to your system via that neutral wire.

Now, what to do.

If it is RFI, then you're going to need a whole mess of shielding and filters that can be pretty expensive (think MRI rooms, for example). But if it's a power quality issue, then it might not be too bad. A diagnostic test might be in order. Look around in your area for qualified testing companies. If they're worth their salt, they'll be able to detect the RFI if it exists and tell you if the noise is on the system. Occasionally the power company has faulty equipment that is actively pumping noise in the system (phase alignment and so on).

To my knowledge the only way to get a truly isolated grounding electrode without employing isolating transformers is by employing a chemical salt ground rod. It's what Electrical Audio uses. And Hospitals. But if it's good enough for Steve, it should be good enough for you, no?