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In Reply to: Not always. posted by Dan Banquer on January 22, 2007 at 04:36:37:
is a large part of the problem. Those line- and neutral-to-ground Y-caps couple RF noise from the line and neutral onto the safety-earth wiring, where it then goes into the audio system to degrade the performance.Attaching shields to earth is important for DC and lower-frequency RF, but has no relevance for the higher-frequency noise that modern appliances generate and that mixes with the audio signal inside most gear and at any corroded connections. The safety-earth wiring is just another complex antenna and distribution network for this noise.
Follow Ups:
I admit it has been a long time ago and I forgot a lot of what I learned, but I woulda thought a physics PhD would have made it possible for me to understand this stuff.My problem is that both Dan and Al, to varying degrees and at different times, seem to be referring to ideal conditions and how things should be, while at other times noting (in different ways) that (very common) imperfect implementation can compromise performance. "Safety" ground is only for safety--sure, I knew that--but it can affect performance. I knew that, too.
I own two residences. One is in the country, near a transformer, in a very quiet environment. The other--where I spend most of my time--is an 11-story condominum complex. I can do anything I want with the former, but I have very little control over the wiring in the latter, except for what happens inside my little corner.
One thing I've discerned--I think--is that a designer has to decide whether to design for an ideal electrical environment or a real, compromised one. If I have total control over my electromagnetic environment, I'm probably better off buying equipment competently designed for an ideal environment. But for situations--like my condo, where at any given moment I can detect 5 different wireless Internet signals and god only knows what the ground is like--I'm probably better off buying equipment competently designed to function in an imperfect environment.
So, to clarify the question:
1. What choices would you make to design for an ideal electrical environment? For a non-ideal environment?
2. Is it possible to design equipment that functions optimally in both ideal and non-ideal environments? Is equipment designed like this limited in performance relative to equipment designed for an ideal environment?
Okay, so that's more than one question, but you get the idea.
Charles Hansen does not seem to have trouble making well-received gear that does not need the AC safety-earth connection.My AC installation is closer to your ideal than your condo examples, but I've determined that my Wadia 861 delivers better performance if I take measures to keep the RF noise out of its grounded AC supply. The safety-earth is part of the issue.
Surely it cannot be that hard to distinguish short from long wires with respect to the frequency of the noise. The only hard part for most folks is to accept that audio gear suffers from noise through the UHF band and beyond. Whether your AC installation is closer to ideal than non-ideal, the quality of the safety-earth wiring only affects lower-frequency noise. In your condo example, non-grounded equipment would have an inherent advantage for rejecting the lower-frequency noise that is likely present on your safety-earth wiring. I don't see how it would have a disadvantage compared to grounded equipment in the ideal case.
If you have grounded equipment, have you investigated an isolation transformer for your audio setup in your condo? A transformer removes the noise present between the safety-earth and AC neutral by shorting the secondary neutral lead to the safety-earth at the transformer. It also filters normal-mode noise through core losses. This is legal and does not require rewiring your building. The downside with most transformers is their limited current delivery capacity. The Acrolink transformer is way over-built and performs well.
"1. What choices would you make to design for an ideal electrical environment? For a non-ideal environment? "
From the aspect of the electronics alone; a properly wired three prong outlet."2. Is it possible to design equipment that functions optimally in both ideal and non-ideal environments? Is equipment designed like this limited in performance relative to equipment designed for an ideal environment?
From the aspect of the electronics alone; a properly wired three prong outlet.
Hope that answers your question, and as you implied in your first post; the theory and applications where done at least thirty years ago.
http://www.audiocircle.com/circles/index.php?topic=8780.0
The above link is a good start; Bill Whitlock recommended that a switch from the signal ground to the chassis/earth ground at the return of the power supply for each unit would give manufacturers and users the options they need.
d.b.
what, precisely, means "properly wired"?
Please see the electrical code, but in general; the hot and neutral are not crooswired and the earth ground goes back to main panel, connected to preferably an incoming water pipe. Since some don't have an incoming water pipe they can use a properly connected stake in the earth, or in the case of some larger apartment the steel frame of the building which can and in many cases is tied to earth ground.
ATTENTION! Please consult an electrician for what is applicable in your residence, as I have outlined some general case scenarios and do not attempt to do any of the above on your own. As for you Jim: consult with an electrician or electrical contracter on what is required.
d.b.
> > As for you Jim: consult with an electrician or electrical contracter on what is required. < <
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