Since these threads seem to be converging again
"Step up to the plate, Fred, and explain this. Demonstrate that you have the understanding you keep claiming I lack. "
There seems little point if you are going to hit me with the pitch each time. I have included references because I just don't know how to explain something to you when you are just going to argue every time and tell me to prove it, hence the references........
I think it is time for you to pitch some questions to someone you feel comfortable
with that can explain it to your satisfaction.
I am not that guy it seems.
http://www.diyaudio.com/forums/showthread.php?postid=248688#post248688
"Step up to the plate, Fred, and explain this. Demonstrate that you have the understanding you keep claiming I lack. "
There seems little point if you are going to hit me with the pitch each time. I have included references because I just don't know how to explain something to you when you are just going to argue every time and tell me to prove it, hence the references........
I think it is time for you to pitch some questions to someone you feel comfortable
with that can explain it to your satisfaction.
I am not that guy it seems.
http://www.diyaudio.com/forums/showthread.php?postid=248688#post248688
Come on folks..........Can't we all just get along? This thread is getting rediculous. We've already hashed out the answer to this question in the first two pages. All this thread has become is one giant flame war. This is not what we are here for. We need to keep in mind that we are here to advance the state of the art in audio, and to help new-comers with problems they are having. Let's keep that in mind, shall we? I'm not trying to get down on anyone, but I think the new-comers might be afraid to ask any more questions if we keep behaving like this. Please try to keep on-topic.
Thanks,
Zach
Thanks,
Zach
Steve Eddy Self Induction...............
Steve Eddy,
You have caused trouble here again and made argument from nothing and annoyed Fred and the rest of us because you ARE UNABLE TO PROPERLY READ THE REFERENCES GIVEN.
The references given by Fred state the following -
This statement from Fred is perfectly correct -
Magnetic noise will induce into both wires.
A balanced differential recieve circuit will reject the common mode noise, and resolve any differences between the conductors.
In future before you go off half cocked and inspire the ire of Fred and others read the references given in full, understand and comprehend them, and then maybe you can add constructive technical input rather than childish personality/ego crap.
In this case think and understand key terms like 'loop area' before shooting your mouth off.
Fred is now in the sin-bin because he reacted to your crap, I just laughed at your crap.
In future you must be sure to fully read references given - you will likely learn, and if you do not understand then ask politely or go and do some research until you do.
If you come out with matter of substance and relevance I will support you (as I have done previously), and if you come out with noise I will slap you down, just like Fred.
Eric.
Steve Eddy,
You have caused trouble here again and made argument from nothing and annoyed Fred and the rest of us because you ARE UNABLE TO PROPERLY READ THE REFERENCES GIVEN.
The references given by Fred state the following -
This statement from Fred is perfectly correct -
Yes magnetic noise will induce differentially if there is any difference in the magnetic field strength at the two signal conductors.
Magnetic noise will induce into both wires.
A balanced differential recieve circuit will reject the common mode noise, and resolve any differences between the conductors.
In future before you go off half cocked and inspire the ire of Fred and others read the references given in full, understand and comprehend them, and then maybe you can add constructive technical input rather than childish personality/ego crap.
In this case think and understand key terms like 'loop area' before shooting your mouth off.
Fred is now in the sin-bin because he reacted to your crap, I just laughed at your crap.
In future you must be sure to fully read references given - you will likely learn, and if you do not understand then ask politely or go and do some research until you do.
If you come out with matter of substance and relevance I will support you (as I have done previously), and if you come out with noise I will slap you down, just like Fred.
Eric.
Hey, Eric, your technical arguments are badly undercut by insult-flinging. Don't do that. Steve's on a moderator-directed hiatus, but will be able to respond to you tomorrow (hopefully on the merits or faults of your argument). Keep it to that in response, or I'll have to ask you to bow out of the thread for a few days. You're a smart enough guy to argue to the point, you don't need to be abusive.
Teams and Members ........
Hi Stuart,
I was not insult slinging mud or insults from my POV (and sorry if it seemed to come out that way), and thanks for the complimentaries.
Look at my post as more like a football coach yelling to pull a member into line to become a TEAM member - sometimes strong terms are used but the intent is sincere and pure in spirit.
This current thing has spilled over into two current threads because of technical mis-information and mis-interpretation on SE's part and as this is most certainly not a first time occurence Fred called enough (a big gutfull) just as I have.
I politely meant the whole post and especially this part -
Hi Stuart,
I was not insult slinging mud or insults from my POV (and sorry if it seemed to come out that way), and thanks for the complimentaries.
Look at my post as more like a football coach yelling to pull a member into line to become a TEAM member - sometimes strong terms are used but the intent is sincere and pure in spirit.
This current thing has spilled over into two current threads because of technical mis-information and mis-interpretation on SE's part and as this is most certainly not a first time occurence Fred called enough (a big gutfull) just as I have.
I politely meant the whole post and especially this part -
Re: Steve Eddy Self Induction...............
Mornin', Eric. Well, morning here anyway.
I read the Whitlock references just fine. And I have absolutely no disagreement with the Whitlock references whatsoever. So I'm at a complete loss as to what I didn't properly read in the Whitlock references.
I'm quite aware of that.
But there was no such "if" qualifying that statement. It was just sitting there on its own in the middle of a post. And despite my questioning that statement several times, no explanation or qualification was ever forthcoming.
And without any qualification or explanation it's saying that there simply isn't any common-mode component to noise induced by magnetic fields. That it's only induced differentially. Which is at odds with my undertanding and why I questioned it.
I didn't go off half-cocked. I questioned a statement that wasn't made in the references given (which again I understood and had no disagreement with) but rather a statement that was sitting by itself in the middle of a post and which was made with no qualifications.
I understand terms like "loop area" just fine. But what has loop area to do with my questioning the statement that I questioned?
Again, I did fully read the Whitlock references. I also understood them. I had no disagreement with anything in the Whitlock references. What I did was question the following unqualified statement which was made in the middle of the post:
Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise.
Is it not relevant to question an unqualified statement which if read without qualification would lead someone to believe something which isn't necessarily the case?
It's simple. Whitlock made the statement that noise induced by magnetic fields is induced common-mode, but with qualifications. The statement I questioned said noise induced by mangetic fields is induced differentially without any qualifications. I found this to be at odds with what Whitlock had said. So I questioned the unqualified statement.
In other words...
Whitlock: Noise will be induced common-mode if both conductors are equidistant from the source and will be rejected in a balanced system which rejects common-mode noise.
Whomever: Noise will be induced differentially and will not be rejected by a balanced interface which only rejects common-mode noise. Period.
se
mrfeedback said:
Mornin', Eric. Well, morning here anyway.
I read the Whitlock references just fine. And I have absolutely no disagreement with the Whitlock references whatsoever. So I'm at a complete loss as to what I didn't properly read in the Whitlock references.
I'm quite aware of that.
But there was no such "if" qualifying that statement. It was just sitting there on its own in the middle of a post. And despite my questioning that statement several times, no explanation or qualification was ever forthcoming.
And without any qualification or explanation it's saying that there simply isn't any common-mode component to noise induced by magnetic fields. That it's only induced differentially. Which is at odds with my undertanding and why I questioned it.
I didn't go off half-cocked. I questioned a statement that wasn't made in the references given (which again I understood and had no disagreement with) but rather a statement that was sitting by itself in the middle of a post and which was made with no qualifications.
I understand terms like "loop area" just fine. But what has loop area to do with my questioning the statement that I questioned?
Again, I did fully read the Whitlock references. I also understood them. I had no disagreement with anything in the Whitlock references. What I did was question the following unqualified statement which was made in the middle of the post:
Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise.
Is it not relevant to question an unqualified statement which if read without qualification would lead someone to believe something which isn't necessarily the case?
It's simple. Whitlock made the statement that noise induced by magnetic fields is induced common-mode, but with qualifications. The statement I questioned said noise induced by mangetic fields is induced differentially without any qualifications. I found this to be at odds with what Whitlock had said. So I questioned the unqualified statement.
In other words...
Whitlock: Noise will be induced common-mode if both conductors are equidistant from the source and will be rejected in a balanced system which rejects common-mode noise.
Whomever: Noise will be induced differentially and will not be rejected by a balanced interface which only rejects common-mode noise. Period.
se
Hi,
In reply to:
http://www.diyaudio.com/forums/showthread.php?postid=249399#post249399
"Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise."
The differential noise should actually be referred to as normal mode noise in descriptions of balanced input circuits.
And now, on to the references.....
3. Twisted Shielded Pair Wiring
For the instrumentation amplifiers to achieve the best noise rejection it is essential that any noise induced in the wiring be common mode. This is best achieved by the use of shielded twisted pair wiring between the sensor or signal source and the
instrumentation front-end. It is important to note that not all “shielded pair” cable are in fact twisted. Cables where the wire pairs simply run parallel to each other are significantly more susceptible to induced normal mode noise caused by fluctuating fields as well as cross coupling between adjacent pairs. The use of shielded twisted pair cable is strongly encouraged. The telephone industry is a testament to the noise immunity that can be achieved through the use of twisted pair cable and differential signaling. They run twisted pair cable for miles along power lines and open country with thunder storms and achieve amazingly low crosstalk and noise pickup …remember the human ear is a marvelous device with a logarithmic response so even the smallest amount of noise or crosstalk can be objectionable.
Connecting Signals to Differential Inputs Bustec Productions Ltd.
http://www.bustec.ie/support/papers/difinput/connecting_signals.pdf
Twisted Pairs of immunity to both electric and magnetic fields.....(to).....Consequenty twisted pair provides better immunity to magnetic fields than two closely spaced parallel conductors
Preventing and Attacking Measurement Noise Problems Campbell Scientific Inc.
http://www.eettaiwan.com/ARTICLES/2002MAR/PDF/2002MAR01_AMD_DSP_AN53.PDF
Signal leads can pickup two types of external noise-common mode and normal mode. Normal mode noise enters the signal path as a differential voltage and cannot be distinguished from the transducer signal. Noise picked up on both leads from ground is referred to as common-mode interference.
http://www.omega.com/literature/transactions/volume2/analogsignal2.html
Inductive Coupling, page 14
Field Wiring and Noise Considerations for Analog Signals Syed Jaffar Shah
http://cires.colorado.edu/~jjose/Noise-analog.pdf
Magnetically Coupled Noise, page 3
Understanding Interference Type Noise David Rich
http://www.analog.com/library/analogDialogue/bestof/pdf/16_3.pdf
A balanced interface can reject any interference — whether because of ground voltage differences, magnetic fields, or electricfields — as long as that interference produces identical voltages, withrespect to ground, on each of the signal lines. Because they're commonto both inputs, these identical voltages are referred to as the common-mode voltage. If everything were perfect, the balanced input circuit would not respond at all to this voltage. However, in the real world, the response is not zero. The ratio of its response to signal (called differential gain) and its response to interference (called common-mode gain) is known as its common-mode rejection ratio (CMRR). Therefore, higher numbers, usually expressed as decibels, mean better rejection of hum, buzz, and other interference. Part1 of this article, which ran in the March 2003 issue, ended with areminder that noise rejection in a balanced signal interface isn't justa function of the CMRR of the balanced input itself. Inescapably,actual noise-rejection performance of the interface depends on how thedriver, cable, and receiver interact. This month I'll explain theeffects of cable construction and its shield connections.
EFFECT OF CABLE CONSTRUCTION
Only two conductors are required to complete the signal circuit, whether aninterface is balanced or unbalanced. The noise rejection in a balanced interface is due to the match in impedances, with respect to ground, of the signal pair. AC magnetic fields induce voltages in wires. The magnitude of the voltage depends on the strength of the field, which depends on the distance between wire and field source. Therefore, equal voltages will be induced in the two wires of a balanced cable only if they are equidistant from the field source. Any voltage difference is added to the signal as noise. Twisting of the two wires is a first-order technique to make induced voltages identical by averaging the physical positions of the wires. Star-quad constructionenhances this idea by parallel connecting two twisted pairs, further reducing susceptibility to magnetic fields by about 40 dB. At audio frequencies, magnetic coupling is totally unaffected by aluminum orcopper cable shielding. Remember that wiring at terminal blocks andinside XLR connectors is vulnerable to magnetic fields because the twisting is opened up, effectively creating a pickup loop.
CMRR IN BALANCED INTERFACES: part 2 BILL WHITLOCK
http://www.svconline.com/ar/avinstall_cmrr_balanced_interfaces_2/
For the applications below, cables should be high quality shielded twisted pair
INTERCONNECTION OF BALANCED AND UNBALANCED EQUIPMENT Bill Whitlock
http://www.jensen-transformers.com/an/an003.pdf
Magnetic pickup loops can easily be created by improper routing of cables. Any closed loop of wire in the proximity of an AC magnetic field will have a current induced in the loop.
HUM & BUZZ IN UNBALANCED INTERCONNECT SYSTEMS Bill Whitlock
http://www.jensen-transformers.com/an/an004.pdf
Cheers,
In reply to:
http://www.diyaudio.com/forums/showthread.php?postid=249399#post249399
"Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise."
The differential noise should actually be referred to as normal mode noise in descriptions of balanced input circuits.
And now, on to the references.....
3. Twisted Shielded Pair Wiring
For the instrumentation amplifiers to achieve the best noise rejection it is essential that any noise induced in the wiring be common mode. This is best achieved by the use of shielded twisted pair wiring between the sensor or signal source and the
instrumentation front-end. It is important to note that not all “shielded pair” cable are in fact twisted. Cables where the wire pairs simply run parallel to each other are significantly more susceptible to induced normal mode noise caused by fluctuating fields as well as cross coupling between adjacent pairs. The use of shielded twisted pair cable is strongly encouraged. The telephone industry is a testament to the noise immunity that can be achieved through the use of twisted pair cable and differential signaling. They run twisted pair cable for miles along power lines and open country with thunder storms and achieve amazingly low crosstalk and noise pickup …remember the human ear is a marvelous device with a logarithmic response so even the smallest amount of noise or crosstalk can be objectionable.
Connecting Signals to Differential Inputs Bustec Productions Ltd.
http://www.bustec.ie/support/papers/difinput/connecting_signals.pdf
Twisted Pairs of immunity to both electric and magnetic fields.....(to).....Consequenty twisted pair provides better immunity to magnetic fields than two closely spaced parallel conductors
Preventing and Attacking Measurement Noise Problems Campbell Scientific Inc.
http://www.eettaiwan.com/ARTICLES/2002MAR/PDF/2002MAR01_AMD_DSP_AN53.PDF
Signal leads can pickup two types of external noise-common mode and normal mode. Normal mode noise enters the signal path as a differential voltage and cannot be distinguished from the transducer signal. Noise picked up on both leads from ground is referred to as common-mode interference.
http://www.omega.com/literature/transactions/volume2/analogsignal2.html
Inductive Coupling, page 14
Field Wiring and Noise Considerations for Analog Signals Syed Jaffar Shah
http://cires.colorado.edu/~jjose/Noise-analog.pdf
Magnetically Coupled Noise, page 3
Understanding Interference Type Noise David Rich
http://www.analog.com/library/analogDialogue/bestof/pdf/16_3.pdf
A balanced interface can reject any interference — whether because of ground voltage differences, magnetic fields, or electricfields — as long as that interference produces identical voltages, withrespect to ground, on each of the signal lines. Because they're commonto both inputs, these identical voltages are referred to as the common-mode voltage. If everything were perfect, the balanced input circuit would not respond at all to this voltage. However, in the real world, the response is not zero. The ratio of its response to signal (called differential gain) and its response to interference (called common-mode gain) is known as its common-mode rejection ratio (CMRR). Therefore, higher numbers, usually expressed as decibels, mean better rejection of hum, buzz, and other interference. Part1 of this article, which ran in the March 2003 issue, ended with areminder that noise rejection in a balanced signal interface isn't justa function of the CMRR of the balanced input itself. Inescapably,actual noise-rejection performance of the interface depends on how thedriver, cable, and receiver interact. This month I'll explain theeffects of cable construction and its shield connections.
EFFECT OF CABLE CONSTRUCTION
Only two conductors are required to complete the signal circuit, whether aninterface is balanced or unbalanced. The noise rejection in a balanced interface is due to the match in impedances, with respect to ground, of the signal pair. AC magnetic fields induce voltages in wires. The magnitude of the voltage depends on the strength of the field, which depends on the distance between wire and field source. Therefore, equal voltages will be induced in the two wires of a balanced cable only if they are equidistant from the field source. Any voltage difference is added to the signal as noise. Twisting of the two wires is a first-order technique to make induced voltages identical by averaging the physical positions of the wires. Star-quad constructionenhances this idea by parallel connecting two twisted pairs, further reducing susceptibility to magnetic fields by about 40 dB. At audio frequencies, magnetic coupling is totally unaffected by aluminum orcopper cable shielding. Remember that wiring at terminal blocks andinside XLR connectors is vulnerable to magnetic fields because the twisting is opened up, effectively creating a pickup loop.
CMRR IN BALANCED INTERFACES: part 2 BILL WHITLOCK
http://www.svconline.com/ar/avinstall_cmrr_balanced_interfaces_2/
For the applications below, cables should be high quality shielded twisted pair
INTERCONNECTION OF BALANCED AND UNBALANCED EQUIPMENT Bill Whitlock
http://www.jensen-transformers.com/an/an003.pdf
Magnetic pickup loops can easily be created by improper routing of cables. Any closed loop of wire in the proximity of an AC magnetic field will have a current induced in the loop.
HUM & BUZZ IN UNBALANCED INTERCONNECT SYSTEMS Bill Whitlock
http://www.jensen-transformers.com/an/an004.pdf
Cheers,
Steve, Steve, Steve. I asked you here to stay away for a couple of days (I'm in the same time zone as you). I clarified via email exactly what I meant by that. And your response to me indicated that you understood exactly what I meant.
What we have here is a failure to commun'cate.
Two days in the box.
But at least you kept to the issues and away from personal stuff, which is why it isn't longer. You couldn't have waited one more sleep cycle?
Re: Re: Steve Eddy Self Induction...............
Steve,
Fred's (Whitlock's) quoted statement is actually perfectly correct and gives no ambiguity.
If regarding more than one conductor (any circuit possible by definition) it follows perfectly that there will be physical seperation of the conductors, and therefore induced differential noise.
If I was a complete novice I would not have badgered Fred without having first digested the references that Fred kindly researched and cited.
Steve, the statement paragraph that you have made issue of, stands perfectly alone and requires no qualification.
Upon reading the cited references the answers/implications regarding audio twisted balanced line systems would be clearly evident, and therefore there would be no need to keep asking Fred to qualify anything.
Quite a few of us around here do go to very much trouble to find technical references so that technical issues can be clearly explained for the novice and expert alike, and Fred is very valuably contextually productive in providing these resources.
When fellow members are provided with multiple resources to follow up on and the intended recipient does not take heed, then tempers can and do flare.
In the past I have politely asked for elaboration/clarification, or seemingly stupid questions of Fred, and have recieved graceful and very informative answers from him.
Next time I think you should say things like "Ummm, I don't quite understand that last point - could you please elaborate ?"
You may get an intelligent answer, or you may be referred back to the citatons (if the answer has already been provided).
Intelligent counsel is all about how you term the questions.
Goodnight,
Eric.
Good morning too you too - 11.15 Pm actually.Steve Eddy said:
Steve,
Fred's (Whitlock's) quoted statement is actually perfectly correct and gives no ambiguity.
If regarding more than one conductor (any circuit possible by definition) it follows perfectly that there will be physical seperation of the conductors, and therefore induced differential noise.
If I was a complete novice I would not have badgered Fred without having first digested the references that Fred kindly researched and cited.
Steve, the statement paragraph that you have made issue of, stands perfectly alone and requires no qualification.
Upon reading the cited references the answers/implications regarding audio twisted balanced line systems would be clearly evident, and therefore there would be no need to keep asking Fred to qualify anything.
Quite a few of us around here do go to very much trouble to find technical references so that technical issues can be clearly explained for the novice and expert alike, and Fred is very valuably contextually productive in providing these resources.
When fellow members are provided with multiple resources to follow up on and the intended recipient does not take heed, then tempers can and do flare.
In the past I have politely asked for elaboration/clarification, or seemingly stupid questions of Fred, and have recieved graceful and very informative answers from him.
Next time I think you should say things like "Ummm, I don't quite understand that last point - could you please elaborate ?"
You may get an intelligent answer, or you may be referred back to the citatons (if the answer has already been provided).
Intelligent counsel is all about how you term the questions.
Goodnight,
Eric.
Just a quick update here.
In post 74 of this thread I asked the following:
Fred, are these words your words, Ott's words, or someone else's words?
Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise.
Reason I ask is that I'm going to call Whitlock on Monday and run this by him and want to give the quote proper attribution.
Fred replied in post 75 saying:
As Sy said we are to deal with the technical issues not personality issues. Why not run the statement in question by Mr. Whitlock and see what he thinks of the premise instead worrying about who said it. The statement should stand on it's own merit rather than who said it. If it is Mr. Whitlock's quote, you should give him proper credit of course. I would hope that you would call him to discuss the topic and not waste his time trying to find the source of a quote. Tell him you read it on the Internet and wondered if it was true.
I thought to myself "fair enough" and did just as Fred had suggested and sent the statement in question to Bill Whitlock without any attribution and without any other context than I had simply "read it on the Internet."
I sent exactly this (grammatical error and all):
Howdy, Bill! (and Dale to whom I'm cc'ing this to in case your verizon.net account is no longer valid)
Was wondering if I might get a quick comment from you (and if may I quote your comment if any in public) regarding the following claim I came across out there on the 'net:
"Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise."
Mr. Whitlock's verizon.net EMail account was no longer active so the first reply I received was from Dale Roche, Jensen's VP of Engineering telling me that he'd forward my EMail on to Mr. Whitlock along with a very short comment on the statement in question.
A short time later I received a reply from Mr. Whitlock, also with a short comment on the statement in question.
However I couldn't post any of these statements in public because Mr. Whitlock said that he would want to have ample time to respond to any further commentary. He'd just got back from AES and said he wouldn't have the time until after the end of the month.
I EMailed Eric and Frank, gave them the short comments and explained that any public commentary would have to wait until sometime after the end of the month.
One of the two forwarded my EMail to them on to Fred who subsequently sent a rather irate EMail to Jensen.
As a consequence of Fred's EMail, it is now Jensen's official policy to not comment on anything having to do with diyAudio.com or any other forum or newsgroup.
So, that's the end of that.
I've apologized to both Mr. Whitlock and Mr. Roche and have accepted full responsibility for the consequences. I should have known better than to have followed Fred's suggestion.
se
In post 74 of this thread I asked the following:
Fred, are these words your words, Ott's words, or someone else's words?
Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise.
Reason I ask is that I'm going to call Whitlock on Monday and run this by him and want to give the quote proper attribution.
Fred replied in post 75 saying:
As Sy said we are to deal with the technical issues not personality issues. Why not run the statement in question by Mr. Whitlock and see what he thinks of the premise instead worrying about who said it. The statement should stand on it's own merit rather than who said it. If it is Mr. Whitlock's quote, you should give him proper credit of course. I would hope that you would call him to discuss the topic and not waste his time trying to find the source of a quote. Tell him you read it on the Internet and wondered if it was true.
I thought to myself "fair enough" and did just as Fred had suggested and sent the statement in question to Bill Whitlock without any attribution and without any other context than I had simply "read it on the Internet."
I sent exactly this (grammatical error and all):
Howdy, Bill! (and Dale to whom I'm cc'ing this to in case your verizon.net account is no longer valid)
Was wondering if I might get a quick comment from you (and if may I quote your comment if any in public) regarding the following claim I came across out there on the 'net:
"Noise induced by varying magnetic fields will be differential and not rejected by a balanced circuit, which rejects common mode noise."
Mr. Whitlock's verizon.net EMail account was no longer active so the first reply I received was from Dale Roche, Jensen's VP of Engineering telling me that he'd forward my EMail on to Mr. Whitlock along with a very short comment on the statement in question.
A short time later I received a reply from Mr. Whitlock, also with a short comment on the statement in question.
However I couldn't post any of these statements in public because Mr. Whitlock said that he would want to have ample time to respond to any further commentary. He'd just got back from AES and said he wouldn't have the time until after the end of the month.
I EMailed Eric and Frank, gave them the short comments and explained that any public commentary would have to wait until sometime after the end of the month.
One of the two forwarded my EMail to them on to Fred who subsequently sent a rather irate EMail to Jensen.
As a consequence of Fred's EMail, it is now Jensen's official policy to not comment on anything having to do with diyAudio.com or any other forum or newsgroup.
So, that's the end of that.
I've apologized to both Mr. Whitlock and Mr. Roche and have accepted full responsibility for the consequences. I should have known better than to have followed Fred's suggestion.
se
Re: Re: Re: Steve Eddy Self Induction...............
It's not Whitlock's statement.
And it's precisely because it gives no ambiguity that it's erroneous and misleading. It says that there simply is no common-mode component to noise induced by varying magnetic fields which means that even a perfectly balanced interface can do nothing about noise induced by varying magnetic fields.
But that's rather at odds with what was stated in the Whitlock references. To wit:
AC magnetic fields induce voltages in wires. The magnitude of the voltage depends on the strength of the field, which depends on the distance between wire and field source. Therefore, equal voltages will be induced in the two wires of a balanced cable only if they are equidistant from the field source.
This seems to indicate that even with physical separation between conductors, if each conductor is equidistant from the source, the induced voltage will be common-mode (assuming balanced impedances of course).
Of course, even if they're not equidistant, there will still be a common-mode component. Let's say with both conductors equidistant, we get 1 volt common-mode across each conductor. Move one closer to the source so you've got 1.5 volts across it. That gives you 0.5 volts differential, but you still have 1 volt common, yes?
It's because I digested the references that I questioned that unqualified, unambiguous statement as it seemed to be at odds with what had been said in the references.
If so, then it is at odds with the references cited. So which is correct? The unqualified, unambiguous statement that stands perfectly alone or the references?
Where in the cited references does it say that there is no common-mode component to noise induced by magnetic fields? If that were the case, then balanced interfaces would be of no use whatsoever with regard to noise induced by magnetic fields, yet the cited references clearly state that they are.
se
mrfeedback said:
It's not Whitlock's statement.
And it's precisely because it gives no ambiguity that it's erroneous and misleading. It says that there simply is no common-mode component to noise induced by varying magnetic fields which means that even a perfectly balanced interface can do nothing about noise induced by varying magnetic fields.
But that's rather at odds with what was stated in the Whitlock references. To wit:
AC magnetic fields induce voltages in wires. The magnitude of the voltage depends on the strength of the field, which depends on the distance between wire and field source. Therefore, equal voltages will be induced in the two wires of a balanced cable only if they are equidistant from the field source.
This seems to indicate that even with physical separation between conductors, if each conductor is equidistant from the source, the induced voltage will be common-mode (assuming balanced impedances of course).
Of course, even if they're not equidistant, there will still be a common-mode component. Let's say with both conductors equidistant, we get 1 volt common-mode across each conductor. Move one closer to the source so you've got 1.5 volts across it. That gives you 0.5 volts differential, but you still have 1 volt common, yes?
It's because I digested the references that I questioned that unqualified, unambiguous statement as it seemed to be at odds with what had been said in the references.
If so, then it is at odds with the references cited. So which is correct? The unqualified, unambiguous statement that stands perfectly alone or the references?
Where in the cited references does it say that there is no common-mode component to noise induced by magnetic fields? If that were the case, then balanced interfaces would be of no use whatsoever with regard to noise induced by magnetic fields, yet the cited references clearly state that they are.
se
Steve Eddy said:
sure. Fred has had a good reputation as someone who is interested in nothing but truth. He is the one given you the reference to Whitlock's paper.
For him to turn around complaining to Jensen does not seem to be consistent with his past record and reputation on this forum. I would have expected that you receive help from him getting clarification on this particular subject from experts including Mr. Whitlock, not the opposite.
So something doesn't seem to be right here and I don't have enough information to figure out what transpired.
thus, my question.
Steve
Sorry to take so long with the drawing..
On the left, a diff wire setup with no twist for clarification (note that ground is not shown in either case, I'm not talking about ground induced, common mode voltage).
On the right, a twisted pair.
On the left...any magnetic flux trapped within the loop...if it changes, there is a voltage generated around that loop, which shows up as a voltage between a and b at the receiver. That voltage is related to the total (integrated) amound of changing flux within that loop...if another source next to it is contributing an opposing changing flux, it's contribution will be added (but opposite polarity voltage).
On the right, due to the twisting, each loop will intercept different polarities of the flux..Loops 1 and 3 will receive the changing flux in the same direction, and 2 and 4 will receive it in the opposite one..So, while 1 and 3 are a duplicate of the directional pickup as the left side diagram, loops 2 and 4 oppose it..And, the net total induced voltage at the receiver will be zero.
Cheers, John
Sorry to take so long with the drawing..
On the left, a diff wire setup with no twist for clarification (note that ground is not shown in either case, I'm not talking about ground induced, common mode voltage).
On the right, a twisted pair.
On the left...any magnetic flux trapped within the loop...if it changes, there is a voltage generated around that loop, which shows up as a voltage between a and b at the receiver. That voltage is related to the total (integrated) amound of changing flux within that loop...if another source next to it is contributing an opposing changing flux, it's contribution will be added (but opposite polarity voltage).
On the right, due to the twisting, each loop will intercept different polarities of the flux..Loops 1 and 3 will receive the changing flux in the same direction, and 2 and 4 will receive it in the opposite one..So, while 1 and 3 are a duplicate of the directional pickup as the left side diagram, loops 2 and 4 oppose it..And, the net total induced voltage at the receiver will be zero.
Cheers, John
Attachments
Ok, so I goofed on whose statement it is.
The next sentence is gramatically incorrect - a conundrum if you will.
The third sentence jumps boundaries in logic and these assertions cannot be made.
What Fred's statement does say is that along the length of any conductor (aerial) a differential voltage will be developed along the length of the said conductor.
If there are two conductors there will be differences in the differential voltages across the individual conductors, AND between the said conductors.
The only condition that I can think of where this does not hold true is when the two conductors trace longtitudinal lines about the surface of a sphere with the magnetic disturbance source at the center of the sphere.
This would give matching EMF for both wires, ie common mode signal only, and no differential EMF between the wires at any points.
Of course in reality this condition CANNOT be met, so yes Fred's statement is perfectly correct in the REAL world.
A well known, tried, proven and ready solution is to twist the two wires so that differential pickup is converted to common mode pick-up by means of averaging the point to point EMF's induced into the two conductors.
The degree of conversion vs frequency is influenced by the conductor cross sectional area, seperation, and twisting cycle length wrt the wavelength of the applied magnetic disturbance.
AC magnetic fields induce voltages in wires. The magnitude of the voltage depends on the strength of the field, which depends on the distance between wire and field source. Therefore, equal voltages will be induced in the two wires of a balanced cable only if they are equidistant from the field source.
So in other words if the two wires are not exactly equidistant from the source then there wil be an induced differential component (in addition to the common mode component).
I thought Fred already said that succinctly in one sentence many posts back.
Where in the cited references does it say that there is no common-mode component to noise induced by magnetic fields? If that were the case, then balanced interfaces would be of no use whatsoever with regard to noise induced by magnetic fields, yet the cited references clearly state that they are.
Neither in the references nor in Fred's statement, but you read that into it.
I am not sure whether the problem is misunderstanding, comprehension or pedantry.
Steve, I feel that you owe apologies to Fred and to all whose time has been squandered on this frankly elementary concept, and I sicerely hope that you have learned lessons in effective communication.
Eric.
SY:
I wonder if it would not be best for the guy being accused of being the villain to respond. I can then verify as to what I accidentally witnessed while he was checking his e-mail.......trying to get hold of his wife at work......... as we were fixing to shove food into our faces in time to watch the Curse of the Billy Goat make everyone in Chicago angry.
More than one person has now made erroneous assumptions. Perhaps they should look up the context of "confidential" in their dictionary.
Jocko
I wonder if it would not be best for the guy being accused of being the villain to respond. I can then verify as to what I accidentally witnessed while he was checking his e-mail.......trying to get hold of his wife at work......... as we were fixing to shove food into our faces in time to watch the Curse of the Billy Goat make everyone in Chicago angry.
More than one person has now made erroneous assumptions. Perhaps they should look up the context of "confidential" in their dictionary.
Jocko
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