Actually, that is entirely incorrect. Where did you get that?
The conductive loop formed by either the safety bond, or even just the neutral conductor can trap time varying magnetic fields and cause a loop current. Also, the entire aftermarket powercord market uses 3 prongs.
Sheesh, even Bill Whitlock is beginning to address the power cordage issue.
The equipment internal design dictates the ground loop susceptibility of all equipment, and that is not within the mandate of any NRTL's. What you cite is about bonding the chassis or double insulating it, that is within the mandate of NRTL's.
Perhaps I can direct you to Tom Van Doren. He has a reasonable presentation online if you wish to learn the topic here.
jn
I did not request a discussion.
I requested you learn what you are speaking about before you speak.
Not after.
It is getting tiring pointing you to experts in the field who teach this stuff for a living. Those who ask questions here have enough to worry about without also worrying about sloppy and haphazard proclamations from people who do not understand the topic.
jn
btw, it is only a useless discussion if you learn nothing. I can point you to books, articles, IEEE standards (although they retired IEEE-1050), even NEC which discusses various parts of this.
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JN,
If you insist: When you make exceptional claims, it is your burden to provide the exceptional proof. Otherwise, expect a big old BS flag being tossed your way.
If you have any factual information that is not the common understanding or industrial standards, support it rather than make snide comments. I am more than willing to learn new things, but I only bother with things that have a fair chance of being correct. So far, you are batting zero based on your explanation and support. That does not mean you may not be correct, it means you have not supported your claims in a coherent format.
" can trap time variable magnetic fields" Yup, every 1/60th of a second. But they go away just as fast. Got DC on your mains? Yup, it will hold up a field. SO WHAT?
There is a aftermarket power cable market selling three wire cords. SO WHAT? They also sell "audio grade outlets" and cryogenic treated plugs. That still provides no factual information suggesting it is anything other than snake oil.
I have dealt with ground loops for a living quite successfully when I was in industry. The hard ones are the RF loops where there is no DC connection. I have dealt with imbalanced phase currents when IBM mandates their CPU be on a different entrance than the third party peripherals inducing thousands of amps, yes thousands of amps, of RF on signal grounds. I have dealt with getting class B equipment through FTC and CSA certification. I do have some knowledge in this area. No knolege is complete, so provide some reasonable support to your claims.
If you insist: When you make exceptional claims, it is your burden to provide the exceptional proof. Otherwise, expect a big old BS flag being tossed your way.
If you have any factual information that is not the common understanding or industrial standards, support it rather than make snide comments. I am more than willing to learn new things, but I only bother with things that have a fair chance of being correct. So far, you are batting zero based on your explanation and support. That does not mean you may not be correct, it means you have not supported your claims in a coherent format.
" can trap time variable magnetic fields" Yup, every 1/60th of a second. But they go away just as fast. Got DC on your mains? Yup, it will hold up a field. SO WHAT?
There is a aftermarket power cable market selling three wire cords. SO WHAT? They also sell "audio grade outlets" and cryogenic treated plugs. That still provides no factual information suggesting it is anything other than snake oil.
I have dealt with ground loops for a living quite successfully when I was in industry. The hard ones are the RF loops where there is no DC connection. I have dealt with imbalanced phase currents when IBM mandates their CPU be on a different entrance than the third party peripherals inducing thousands of amps, yes thousands of amps, of RF on signal grounds. I have dealt with getting class B equipment through FTC and CSA certification. I do have some knowledge in this area. No knolege is complete, so provide some reasonable support to your claims.
GP, Nice tag line quote. I deal with customers giving me the solution rather than the business needs every day. The other day I had a customer insist he wanted a solution using H-Base, but his problem was transactional.
The question is not weather we are still active, it's if our spouse still is! ( ya young whippersnapper you
)
The question is not weather we are still active, it's if our spouse still is! ( ya young whippersnapper you
)
Yup, DEFECTIVE plant power can cause issues. Nothing a power cable can fix. Just as defective design is not fixed by a power cord. If JN has some new insight from his classroom, he has not explained it. We all know a current flowing generates a magnetic field no matter how many fancy words were used to describe it.
None of this has anything relevant to speaker cable vs. signal cable length that has been explained, which is what I said in the first place. Bringing up power cords in the discussion of ground loops and long cables is just plain blowing smoke past maybe a comment that a DEFECTIVE power cable could cause a safety issue that may be made obvious by a defective neutral or ground.
I am fully open to any peer reviewed documentation to say my direct experience and old textbooks are no longer valid.
None of this has anything relevant to speaker cable vs. signal cable length that has been explained, which is what I said in the first place. Bringing up power cords in the discussion of ground loops and long cables is just plain blowing smoke past maybe a comment that a DEFECTIVE power cable could cause a safety issue that may be made obvious by a defective neutral or ground.
I am fully open to any peer reviewed documentation to say my direct experience and old textbooks are no longer valid.
The question is not whether we are still active, it's if our spouse still is! ( ya young whippersnapper you
No, not that.
By sexual activity I only mean my insistence to screw-up ground loops.
(I was following your line of thought)Posts #59, 60, 61 need some revisit. They are not long but they are 'dense'.
http://www.ewh.ieee.org/r5/denver/rockymountainemc/archive/2004/October/Experimental_Demo.pdf
George
From Bryston and I quote: " As long as the power cord can deliver the current and voltage required to drive the amplifier to full power it is as good as it can get"
Van Dorn paper cited above is very good. Nothing new. A more practical set of papers would be those on Jensen Transformers pages. Like Bryston, they understand getting a signal across the room very well. THAT has some good practical papers too.
NOTHING here has provided any support that bringing up power cords is other than blowing smoke. That is the total extent of what I am waving the flag about. The OP wanted the question answered as the Bryston summary provided.
How about something relevant to the question? Current drive and source impedance maybe? A cheap preamp with a low power op-amp output, or gasp, passive preamp's variable impedance inability to drive a cable? This could effect the best solution for the OP. How about practical lengths? Maybe a rule of thumb, how long a single ended cable before you should invest in balanced lines. How long a 16 ga zip before it has any audible effect? 2 meters? 20 meters? When would going to 12Ga help? Or hurt? When is a twisted pair for single ended with a shield on one end only a help? Which end and why?
Van Dorn paper cited above is very good. Nothing new. A more practical set of papers would be those on Jensen Transformers pages. Like Bryston, they understand getting a signal across the room very well. THAT has some good practical papers too.
NOTHING here has provided any support that bringing up power cords is other than blowing smoke. That is the total extent of what I am waving the flag about. The OP wanted the question answered as the Bryston summary provided.
How about something relevant to the question? Current drive and source impedance maybe? A cheap preamp with a low power op-amp output, or gasp, passive preamp's variable impedance inability to drive a cable? This could effect the best solution for the OP. How about practical lengths? Maybe a rule of thumb, how long a single ended cable before you should invest in balanced lines. How long a 16 ga zip before it has any audible effect? 2 meters? 20 meters? When would going to 12Ga help? Or hurt? When is a twisted pair for single ended with a shield on one end only a help? Which end and why?
How is the statement that a power cord is part of a ground loop "exceptional"?
How is the statement that a ground loop traps time varying magnetic fields "exceptional"?
How is the statement that equipment is sensitive to ground loop currents "exceptional"?
You continue to toss strawmen about in a flailing attempt at saving face. You need to sit back, read properly and accurately, and certainly a lot slower.
My so called "snide remarks" are your fiction, as is your "attack me" statements. You might as well quit that schtick, it does not serve you well.
You have demonstrated time and again that you are not. You are instead, making grand proclamations about engineering you do not understand.
I did notice that you seem afraid of eloquent explanations. That is not my problem, but yours.
Take this gem for example:
That statement leads me to believe that you have no engineering degree. You seem to believe time varying magnetic fields is either 60 hz or DC.
Time variable magnetic fields are non DC entities. Faraday's law of induction predicts the voltage around a conductive loop as a result of time varying magnetic field trapped within the loop.
What a ridiculous statement.
You do not demonstrate that well at all.
I have been, you have ignored it.
What in the world are you talking about? Your prose is, hmmm, somewhat familiar. Are you westom?
You need to learn faraday's law of induction.
Then why did you suddenly decide to attack the statement I made regarding the bryston link being bog standard stuff with the exception of their power cord verbage. It was a standalone comment, not intended to apply to speaker wire. YOU were the one to get all hot and bothered.
You've stated that several times now, yet you ignore everything presented.
You even glossed past Tom Van Doren's presentation without reading or learning.
Go back to it, start all over, and read slowly. Stare at 1-1, 1-4, 1-11, 1-15, 1-17. Think of those pics with respect to audio systems, and please ask questions!! You need to learn this stuff.
After you've started to grasp them, we can move on to chapter 3. You must understand chapter 1 first, because you will continue to make rudimentary mistakes until you get that section.
jn
ps.. I would prefer peer discussion. However, you seem more inclined to act like an unruly student, so I can accommodate that as well. It is of course, your choice.
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A power cord completes a ground loop. When it does, magfield trapping becomes a concern. The power cord can affect the system by the safety bonding conductor and contact resistances and their size relative to the overall loop resistance. Also, if the cord's magfield is asymmetric with respect to it's safety bonding conductor, it can couple haversine currents into the formed ground loop as well as the gated audio currents through the bridge rectifier in the supply.
I have itemized the points you did not understand. Go back and read. edit: btw, Tom is a really nice guy, presents well in person, and is certainly open to learning new things as well.
Which is why I specifically mentioned Bill Whitlock's presentations. You do know who he is, right?
IEEE-STD-1050 was also great for explanations of victim and aggressor, that was actually the first place I noticed using that terminology. It also had some good understandings on how shielding can be compromised by the loop topology.
I thank you for this opportunity to show you things you missed.
jn
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Bryston appears to ignore all the hoopla over speaker cables, tending towards the Roger Russel type of analysis, that of big enough gauge for the application. As well, they tend to limit IC discussion to capacitance, which is certainly viable.
The only caveat I see personally with the IC vs speaker wire length discussion, is the possibility of ground loops affecting the IC's if those are chosen as the long items. Bryston also mentions balanced there, so even long lengths there are quite ok.
I've used various combinations of long speaker wires and long IC's, and really the only issue I've had was with long unbalanced IC's (in the 125 foot range), they'll go all noisy on ya if you don't take care of the ground loop.
Note that I do not sit in the sweetspot to listen, my apps were more about total spl and low noise.
jn
tvr: excellent. you've been having problems with new concepts, going all ostrich is probably your best option. If you want information sources, let me know, I can send you some.
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While Jim Brown would argue that "ground loop" is not the correct description of the problem, still the Safety Ground does have an impact on audio quality.
*******************************************
Two good Bill Whitlock papers on the subject:
"Ground Loops: The Rest of the Story"
Bill Whitlock, AES Fellow and Jamie Fox, P.E.
This paper was presented at the AES 129th Convention, 4-7 November 2010, San Francisco, CA, USA
ABSTRACT
The mechanisms that enable so-called ground loops to cause well-known hum, buzz, and other audio system
noise problems are well known. But what causes power-line related currents to flow in signal cables in the first
place? This paper explains how magnetic induction in ordinary premises AC wiring creates the small voltage
differences normally found among system ground connections, even if “isolated” or “technical” grounding is
used. The theoretical basis is explored, experimental data shown, and an actual case history related. Little
has been written about this “elephant in the room” topic in engineering literature and apparently none in the
context of audio or video systems. It is shown that simply twisting L-N pairs in the premises wiring can
profoundly reduce system noise problems.
http://xa.yimg.com/kq/groups/20963848/268252969/name/Whitlock-Fox+-+Ground+Loops+.pdf
*********************************************************************
"An Overview of Audio System Grounding and Interfacing"
by
Bill Whitlock, President
Jensen Transformers, Inc.
Life Fellow, Audio Engineering Society
Life Senior Member, Institute of Electrical & Electronic Engineers
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
No argument with Mr. Whitlock.
Slide 52 and 53 makes the very point from a previous non-discussion. Maybe our dear prof here would like to discusses with Bill. He should review slide 99 first.
Slide 62 provides one of those general rules the OP was looking for.
Slide 70, yea, how many "pro" inputs rely on 5% resistors and op amps for a balanced receiver! This will keep Jensen in business for a long time.
Slide 82. Yup. Maybe I consider less than this "defective" as I have understood it in a practical sense fixing the noise n a school PA in '73.
Slide 84, my friends at Storm, Gore, and Belden may take exception to the comment.
Slide 92. Here is another good rule of thumb. Somehow this contradicts his "elephant in the room" statement though.
Slide 94, now that is something I did not know. Good thing by habit I use Belden mic cable for my balanced lines.
Slide 96, Hmmm, where is my Newark catelog.
Slide 104, we did that method in freshman communications in '75. I guess it is still a mystery.
Slide 113, Slick, I would never have come up with that. Obvious when he says it.
Twisting the N-L would be fine, but unless you are building new and running in conduit, you don't have that opportunity. The electrical inspector would freak if he saw romex twisted. More than a twist or so every few feet, they will make you rip it out. Risk of a kink is their issue, not magnetic pollution. Maybe the world would be a better and quieter place if it was twisted, but alas, we work within the constraints of the real world.
Slide 52 and 53 makes the very point from a previous non-discussion. Maybe our dear prof here would like to discusses with Bill. He should review slide 99 first.
Slide 62 provides one of those general rules the OP was looking for.
Slide 70, yea, how many "pro" inputs rely on 5% resistors and op amps for a balanced receiver! This will keep Jensen in business for a long time.
Slide 82. Yup. Maybe I consider less than this "defective" as I have understood it in a practical sense fixing the noise n a school PA in '73.
Slide 84, my friends at Storm, Gore, and Belden may take exception to the comment.
Slide 92. Here is another good rule of thumb. Somehow this contradicts his "elephant in the room" statement though.
Slide 94, now that is something I did not know. Good thing by habit I use Belden mic cable for my balanced lines.
Slide 96, Hmmm, where is my Newark catelog.
Slide 104, we did that method in freshman communications in '75. I guess it is still a mystery.
Slide 113, Slick, I would never have come up with that. Obvious when he says it.
Twisting the N-L would be fine, but unless you are building new and running in conduit, you don't have that opportunity. The electrical inspector would freak if he saw romex twisted. More than a twist or so every few feet, they will make you rip it out. Risk of a kink is their issue, not magnetic pollution. Maybe the world would be a better and quieter place if it was twisted, but alas, we work within the constraints of the real world.
In the old days when iron/steel conduit was regularly used and it's continuity back to the Distribution board was tested, the screening effect of the conduit would be far better than a woven and foil screen could achieve.
The close coupling of the Flow and Return mains wiring gives us a fairly good attenuation of EMI for all distances greater than 1m.
It's when the close coupling is broken, or we get down to 300mm (and less) that attenuation of EMI is not as good as it can be.
Tvr,
are your "slides" referring to the second link in post78?
If not, where?
The close coupling of the Flow and Return mains wiring gives us a fairly good attenuation of EMI for all distances greater than 1m.
It's when the close coupling is broken, or we get down to 300mm (and less) that attenuation of EMI is not as good as it can be.
Tvr,
are your "slides" referring to the second link in post78?
If not, where?
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