Grounding Myths

[ddawg16]

They most certainly CAN BE.



And from where, exactly, do these "electronics and sound systems" get their power?

If there is an induced (or leaked) AC current on the neutral (or worse, EGC) due to a ground loop in the building's wiring, that can EASILY play hob with the operation of said "electronics and sound systems".



Not to sound rude, but you seem like the typical sparky who thinks ONLY in terms of building wiring (and perhaps secondarily about the safety issues specific to that very limited scope), with no regard to what is OPERATED off that building wiring.

If a ground loop in the AC ground is causing issues with AV equipment....then the power supply in the AV equipment is either a POS and/or you have the commons in your AV audio hooked up wrong.

A good AV designed system should be totally independent of any earth ground....in other words, there should be no change in quality if the ground is connected or not. Back in the old days....power supplies were real transformers....the effectively decoupled the DC side from the AC source. My old Kenwood has only a 2 prong cord....no earth ground. You can ground the case or not....makes no difference in sound.

 

[ishiboo]

If a ground loop in the AC ground is causing issues with AV equipment....then the power supply in the AV equipment is either a POS and/or you have the commons in your AV audio hooked up wrong.

A good AV designed system should be totally independent of any earth ground....in other words, there should be no change in quality if the ground is connected or not. Back in the old days....power supplies were real transformers....the effectively decoupled the DC side from the AC source. My old Kenwood has only a 2 prong cord....no earth ground. You can ground the case or not....makes no difference in sound.

I think a lot of "ground loop" issues are actually simple RF interference/etc. that "comes in" to the equipment on the ground, as it's sometimes attenuated by the metal structures of the equipment, the fact that the ground runs electromagnetically coupled to the hot/neutral wires for long lengths of time, etc. Similar reasons that data/audio/etc. cables can cross perpendicular to an AC run, but should not be parallel and close proximity to said run.

I have a pair of KRK Rokit 6 speakers at my desk. When I bought them, they had a pretty good buzz to them. A former acquaintance of mine is an engineer for Cerwin Vega, same parent company as KRK. He suggested I disconnect the grounds. As I had made my own exact-length *********** cables anyway, I simply disconnected the grounding pin at the plug side and the problem went away. The speaker chassis/etc. is fiberglassed wood, the only real reason for the grounding is the back amplifier panel.

If it was a metal chassis piece of equipment I was often touching wet or outside or something, I would have tried some filters/chokes/etc. to attempt to resolve the problem.

 

[ddawg16]

I'm the kind of guy who would pull out the oscope and start having a look at what is really going on.

 

[ishiboo]

I'm the kind of guy who would pull out the oscope and start having a look at what is really going on.

It sounded pretty much like it was just power, 60hz interference is usually pretty distinct Really a design flaw in the KRKs I'm sure, not being able to handle it.

 

[Speedy Petey]

Not to sound rude, but you seem like the typical sparky who thinks ONLY in terms of building wiring (and perhaps secondarily about the safety issues specific to that very limited scope), with no regard to what is OPERATED off that building wiring.

And you sound like a narrow minded engineer type that OVER thinks things.
"secondarily about the safety issues specific to that very limited scope"?? Get over yourself, and stop with the thinly veiled insults. If you want to insult me come right out and do it.


Now go back and re-read what I wrote. I DID day it can cause problems with sound and AV systems. It does NOT have anything to do with the effectiveness and workings of the AC wiring in the home, or with things such as lighting as the poster suggested.
I firmly stand by what I wrote.

 

[CNGsaves]

^ ^ ^ Nailed it Speedy. Most of posts by 2MP are nearly 5,000 characters long, and have umpteen jillion re-quotes of every conceivable text or picture.

The GJ server is beginning to have 2MP post-anxiety !!

 

[2ManyProjects]

And you sound like a narrow minded engineer type that OVER thinks things.

The corollary (and necessary prerequisite) to "measure twice, cut once" is "think three times."

"secondarily about the safety issues specific to that very limited scope"?? Get over yourself, and stop with the thinly veiled insults. If you want to insult me come right out and do it.

Just returning what you were dishing out. Physician, heal thyself.

Now go back and re-read what I wrote. I DID day it can cause problems with sound and AV systems.

No. What you SAID was, a ground loop WITHIN the sound/AV system can cause problems, but one within the building wiring (to which that sound/AV system is connected, perhaps in multiple places) cannot. That is wrong.

It does NOT have anything to do with the effectiveness and workings of the AC wiring in the home, or with things such as lighting as the poster suggested.

The poster you refer to ("Engineer61") did not even mention lighting. He did mention lightNing. So much for "go back and read [what was written]."

I firmly stand by what I wrote.

If you say so.

^ ^ ^ Nailed it Speedy. Most of posts by 2MP are nearly 5,000 characters long, and have umpteen jillion re-quotes of every conceivable text or picture.

Better that, than to mislead through oversimplification and/or too many sweeping generalizations set in absolute terms.