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In Reply to: They worry about it now. posted by Jim Austin on January 18, 2007 at 13:17:30:
Yep; the basics and the application were done years ago. The only problem as I see it is to get the consumer audio industry to agree on a grounding standard and figure out just exactly how are they going to use a three prong plug. BTW: just in case you weren't aware of it, good grounding practices reduce interference.
Follow Ups:
It's my understanding--never made the measurement, which isn't easy--that even a reasonably effective earth ground can have several ohms or more between it and true, ideal earth ground. So noise on the ground line isn't necessarily immediately sucked right down into the ground where it can't do any harm.Also, it has been my experience--which admittedly is limited--that there are lots of houses out there with lots of receptacles that are not properly grounded. It seems to me that you would want your equipment to function reasonably (and be safe) even in such installations.
I wonder if someone (Dan? Charles?) can help me understand what, if any, are the implications of these two facts for designing audio electronics.
Any takers?
The purpose of the third power wire (commonly called the 'ground') is to provide an independent path for fault current in order to trip the circuit breaker before the faulty equipment can kill someone.The purpose of the earth attachment is to limit the power system potential rise in the event of a lightning strike. In most USA installations, the utility step-down transformer secondary center tap is attached to earth at the transformer, and each customer's entrance panel is also attached to earth. The earth is not a very good conductor, and there can be many ohms of resistance between these points. Lightning has sufficient force to overcome this setup if it strikes too close, but the arrangement does provide some protection against induced surges.
There is much confusion in audio because circuits contain zero reference points called 'grounds' and this sounds a lot like the term used in the power wiring nomenclature. The impedance between any point in a circuit and the zero reference point depends on the wavelength: for the audio band in domestic situations, all wires are "short" and can be considered as simple lumped elements of resistance, inductance, and capacitance. However, for higher frequencies, the distance becomes a factor and the wire must be treated as a transmission line.
Some audiophiles with technical training and who should know better have installed independent earth connections for the AC circuits feeding their equipment, and report improved performance. This leads to the idea that the quality of the earth connection is important for audio performance, and questions such as yours. An independent earth connection is a very bad idea for safety reasons, but I won't go into detail here.
The quality of the earth connection is important for the safety reasons listed above. It has an influence on the noise environment of the audio system, but not for the reason you stated. The noise environment includes the frequency ranges from audio through UHF and possibly beyond. The safety-earth wiring, no matter how well made, is far too long to be an effective 'ground' connection for much of this frequency range. Modifying the safety-earth wiring will change the noise environment, but not eliminate the basic problem.
Equipment that is double-insulated can avoid connection to the safety-earth power wire and any noise carried on that wire. This is the best solution that I can see. Unfortunately, much audio equipment requires connection to the safety-earth for safety. The noise that enters the system through these connections limits the ultimate performance. Audio systems contain their own noise sources, so this ultimate limit may not be relevant if the internal noise sources have not been addressed.
If earth ground is for safety only then I would like to note the following.
If we look at your typical AC line input filter schematic from Corcom. we note a small cap going to earth ground.
If we look at how a screen room is constructed we note that the entire metal housing of the screen is earth grounded.
If we look at some of the chassis's that are used in some instrumentation we note that the chassis has a fine mesh metal screen over the fan, and in addition the chassis will also contain adhesive copper fingers that are placed along the internal sides to reduce the discontinuities of the chassis.
In balanced connections pin 1 of the XLR connector on much of pro equipment is connected to earth and is typically called "shield".I also note that in talking with a computer technician that he can't use his cell phone and work on an open computer, he has to close it up. It would appear that the earth grounded case of the computer is acting as a shield for the HF frequencies in the above example.
It would appear from the above that certainly a fairly large part of the electronics industry uses earth ground as a shield.
d.b.
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.
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. < <
I am not sure an actual ground connection is required for a closed metal enclosure to keep RFI in, (or out!)It is far to long since I studied this, but such an enclosure, originally called a Faraday cage simply needs to be a fully enclosed conductive "wrapper".
In cold-war days it was beleived that keeping your emergency transistor radio in a biscuit-tin would make it immune to EMP from a an atomic bomb. I never did this experiment.
Yes; a Faraday cage is an option; however, the ready, cheap availability of a three prong plug for many appplications does have plenty of things going for it.
d.b.
the wiring is ancient or incorrect and not up to present day standards. For starters I would recommend some reading on the electrical code for earth grounding under different situations. Many of us who live in urban/suburban areas have the earth ground connected to the incoming water pipe. This makes a very suitable earth ground as the pipes on the incoming side must be conductive/metal, The waste side can be non conductive, to the best of knowldge.
Another thing you can do is go to Home Depot and try to find a two prong outlet, and then ask yourself the following: When was the last ime I saw a computer or microwave oven with a two prong plug? The three prong plug has been around for at least twenty years and it is up to the house owner to bring the property up to present day code.
I urge folks who rent to work with the property owner on this, as I did many years ago.
For an earth ground to be as bad as some people claim; I would suggest that calling in an electrician to verify that your residence is up to present day code.
d.b.
Dan, you are correct. In any modern construction, the waste feed to the street is typically spec'ed as schedule 40 PVC. Water feeds from the street are copper tubing, usually taken directly off of a spool to keep a contiguous run from the street valve to the meter valve.I've built 3 houses in the past 20 years and they were all done this way.
And now you know why I say to people the following:
Call your electrician first!
d.b.
Good grounding reduces hum, yes, but not necessarily RF.
RF noise travels on the AC safety earth wiring. Audio equipment with casework attached to the AC safety earth contains deliberate or accidental (or both) pathways that couple RF noise to the audio signal. Awareness is the first step towards understanding.
< < Audio equipment with casework attached to the AC safety earth contains deliberate or accidental (or both) pathways that couple RF noise to the audio signal. > >That is my experience, too. That is why the Ayre gear uses double insulation -- so that we don't have to connect the case to the AC safety ground. Sounds much better that way.
So the rest of industrial electronics and scientific instrumentation
have it backwards? Or are you guys just victims of bad house wiring & coroded earth grounds?
ROTFLMAO
d.b.
Gee, Dan. It's easy to see why your products sounded so good and your company was so successful.
Answer the question Charles. Why does the rest of electronics not have the issues you and AL S. are having?
d.b.
Well, at least you stopped rolling on the floor. Maybe it will be easier to actually listen now. You should try it some time.
Still ROTFLMAO;
d.b.
Consumer audio is in the mess it's in. Mistaken attitudes and misinformation such as you have posted are in direct contradiction to what the rest of electronics already knows, and has known for many years.
I don't mean to be a snot here Ozzie, but that's the way it is.
d.b.
Try this link; http://www.audioholics.com/techtips/audioprinciples/interconnects/bulletproofingsysteminterf.php
Sorry to get you in Dutch with Charles. I don't disagree that proper AC grounding can reduce RF. Can! But it may not necessarily do so, as the original posters implied, by using expensive AC cables. Now to me, that may qualify as missinformation. Not by the poster, but by the manufacturers of the cables. How many of those high dollar cables are bought to resolve a problem that simply does not exist? Or that if the power supply and cabinent grounding of the component was properly done, incoming RF would be pretty much a non issue as was mentioned above as well? It sounds like Charles' grounding scheme works quite well. At a much lesser cost than an 1800 dollar cable.
< < It sounds like Charles' grounding scheme works quite well. At a much lesser cost than an 1800 dollar cable. > >Sorry to disappoint, but everything makes a difference. And the differences are cumulative. Using a good power cord helps the sound even when using a good grounding scheme.
In other words, I haven't found a grounding scheme that negates the need for good sounding power cords. Just like nobody has yet made a DAC that sounds the same with all CD transports.
On the other hand, there isn't always a direct correlation between price and performance. You might be able to find a nice sounding power cord for less than $1800.
< < It sounds like Charles' grounding scheme works quite well. At a much lesser cost than an 1800 dollar cable. > >Sorry to disappoint, but everything makes a difference. And the differences are cumulative. Using a good power cord helps the sound even when using a good grounding scheme.
--- Care to qualify that statement? When there is no problem with RF in the first place for one's application, why bother with any AC power cord tweak? Because they look cool and will impress one's friends with the latest purchase? I bought a Digital AC cable for my Sony 777 just to see if it would make a difference. It made no difference whatsoever to the sound. I guess either I don't have externally generated RF or the chokes on the AC input are doing their intended job. Luck or good engineering? I'll take either as I am results oriented.
In other words, I haven't found a grounding scheme that negates the need for good sounding power cords. Just like nobody has yet made a DAC that sounds the same with all CD transports.
--- Why not just include one in with your player in the first place? You can use my response below if you want. I just can't believe that any combination of L & C can cost as much as these cables do. The claims of cryogenic treatments are yet another story altogether.
On the other hand, there isn't always a direct correlation between price and performance. You might be able to find a nice sounding power cord for less than $1800.
--- While I will not dispute that different quantities of L & C may negate RF at different frequencies, it seems that review claims always seem to be made that the higher dollar AC cables sounds better. Hmmm?
< < I bought a Digital AC cable for my Sony 777 just to see if it would make a difference. It made no difference whatsoever to the sound. > >If you can't hear the difference, count your blessings and go buy a few more CD's with the money you saved.
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