Steve Eddy said:
Some people just don't know when to keep quiet.........
http://www.benchmarkmedia.com/appnotes-a/clnmicpr.asp
From above:
"The second source, and perhaps the most pernicious, is that of RF induced IM distortion. This is a result of 1) amplifier stages that have not been protected from strong external RF signals, and 2) from a lack of proper feedback compensation which allows the amplifier to intersect its open loop gain curve. When this occurs in the presence of RF, the amplifier becomes non-linear and intermittent IM distortion is the result. And intermittent it often is. A product may measure well on the bench, but when placed into a system or when taken into the field, users may find that its performance is far less than stellar. Here at Benchmark, we are convinced that most of the "bite", "edge", and otherwise undesirable characteristics of many amplifier designs are a result of poor RF immunity. RF causes non-linearity to create new, unexpected, and unwanted audio signals from the incoming audio. And whether you want it or not, this new extra audio comes free with most mic-preamps! To achieve truly clean audio at 30 kHz, the 3 dB bandwidth should extend past at least 200 kHz and still be RF stable. This is no trivial task! "
Shielding and grounding is not as slam dunk as some might believe. For actual expert advice instead of slightly informed speculation:
http://www.emclab.umr.edu/emcbooks.html
Re: Re: Re: Re: Re: Re: Re: Waterpipe Grounding
I don't know what part of the US you're in, but here in California, the safety ground is tied to neutral at the service panel. Neutral is the center tap of the 220 volt distribution transformer. This node is then tied to earth ground. The safety ground is NOT just stuck in the ground with no other connection to the distribution system.
se
grataku said:
I don't know what part of the US you're in, but here in California, the safety ground is tied to neutral at the service panel. Neutral is the center tap of the 220 volt distribution transformer. This node is then tied to earth ground. The safety ground is NOT just stuck in the ground with no other connection to the distribution system.
se
I've nothing further to say to either you or Fred.
I'll believe that when I see it........ RF grounding and shielding is a complicated subject and you might do a little reading on the subject before you embarrass yourself with you usual diatribes. There are subjects that can't be disscussed in 4 paragraphs on a forum. Sorry that the world is not as simple as you would like. A good place to start:
http://www.emclab.umr.edu/
The text I have read and can recommend are:
Introduction to Electromagnetic Compatibility
C.R. Paul, John Wiley Interscience, NY, 1992.
Noise Reduction Techniques in Electronic Systems, second edition
H.W. Ott, John Wiley Interscience, NY, 1988.
Printed Circuit Board Design Techniques for EMC Compliance
Mark Montrose, IEEE Press, 1995.
Grounding and Shielding Techniques in Instrumentation
R. Morrison, Third Edition, John Wiley and Sons, 1986.
High-Speed Digital Design: A Handbook of Black Magic
Howard W. Johnson and Martin Graham, Prentice-Hall, 1993.
High-Frequency Measurements and Noise in Electronic Circuits
Douglas C. Smith, John Wiley and Sons, 1993.
Transmission Line Design Handbook
B. Wadell, Artech House, 1991.
I'll believe that when I see it........ RF grounding and shielding is a complicated subject and you might do a little reading on the subject before you embarrass yourself with you usual diatribes. There are subjects that can't be disscussed in 4 paragraphs on a forum. Sorry that the world is not as simple as you would like. A good place to start:
http://www.emclab.umr.edu/
The text I have read and can recommend are:
Introduction to Electromagnetic Compatibility
C.R. Paul, John Wiley Interscience, NY, 1992.
Noise Reduction Techniques in Electronic Systems, second edition
H.W. Ott, John Wiley Interscience, NY, 1988.
Printed Circuit Board Design Techniques for EMC Compliance
Mark Montrose, IEEE Press, 1995.
Grounding and Shielding Techniques in Instrumentation
R. Morrison, Third Edition, John Wiley and Sons, 1986.
High-Speed Digital Design: A Handbook of Black Magic
Howard W. Johnson and Martin Graham, Prentice-Hall, 1993.
High-Frequency Measurements and Noise in Electronic Circuits
Douglas C. Smith, John Wiley and Sons, 1993.
Transmission Line Design Handbook
B. Wadell, Artech House, 1991.
Re: Re: Re: Re: Re: Re: Re: Re: Re: Waterpipe Grounding
Here the safety ground being tied to netural (and thence to ground) at the service panel is a requirement of the US National Electric Code (NEC). I'm sure you've something similar there in Canada.
Let's see if they have the bug fixed.
<center>
<img src="http://www.q-audio.com/images/wiring.jpg">
</center>
Yayyyyyyy!
The two white vertical strips represent the top and bottom of the secondary of the distribution transformer which is 220 volts. The bus below that where the earth ground, neutral and safety ground connect is the center tap of that transformer.
se
Peter Daniel said:
Here the safety ground being tied to netural (and thence to ground) at the service panel is a requirement of the US National Electric Code (NEC). I'm sure you've something similar there in Canada.
Let's see if they have the bug fixed.
<center>
<img src="http://www.q-audio.com/images/wiring.jpg">
</center>
Yayyyyyyy!
The two white vertical strips represent the top and bottom of the secondary of the distribution transformer which is 220 volts. The bus below that where the earth ground, neutral and safety ground connect is the center tap of that transformer.
se
Re: I've nothing further to say to either you or Fred.
So you haven't sufficient understanding of it yourself to explain how tying your audio equipment reference grounds to an actual earth ground makes a difference?
I'm sorry, but too often I've found that those who refuse to offer anything more specific than "go read a book" are just using that tactic as a ruse to conceal a lack of understanding on their part.
If you understand it, you can explain it.
se
Fred Dieckmann said:
So you haven't sufficient understanding of it yourself to explain how tying your audio equipment reference grounds to an actual earth ground makes a difference?
I'm sorry, but too often I've found that those who refuse to offer anything more specific than "go read a book" are just using that tactic as a ruse to conceal a lack of understanding on their part.
If you understand it, you can explain it.
se
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Waterpipe Grounding
Whoo! Looks like I grossly overestimated the intelligence of the NEC. The 120V distribution should have given me a hint. That's the most dangerous and f'd up connection I have ever seen. When I was a youngster in italy watching american movies I was perplexed as to why the trick of the hair drier in the bathtub worked at all, now I know.
Steve Eddy said:
Here the safety ground being tied to netural (and thence to ground) at the service panel is a requirement of the US National Electric Code (NEC). I'm sure you've something similar there in Canada.
Let's see if they have the bug fixed.
<center>
<img src="http://www.q-audio.com/images/wiring.jpg">
</center>
Yayyyyyyy!
The two white vertical strips represent the top and bottom of the secondary of the distribution transformer which is 220 volts. The bus below that where the earth ground, neutral and safety ground connect is the center tap of that transformer.
se
Whoo! Looks like I grossly overestimated the intelligence of the NEC. The 120V distribution should have given me a hint. That's the most dangerous and f'd up connection I have ever seen. When I was a youngster in italy watching american movies I was perplexed as to why the trick of the hair drier in the bathtub worked at all, now I know.
Fred Dieckmann said:
And some people just don't know how to read and follow a discussion.
What's described in the text you quote is classic instability. Now go back and read what I said originally:
Well, unless the RF is causing instability (i.e. oscillation), the system typically maintains linearity within the audio band. The problem is that EMI outside the bandwidth of the amplifying device can result in intermodulation products down in the audio band.
The point I was trying to make is that just because you have intermodulation products from RF in the audio band (in other words, those products are the products of the RF frequencies, NOT audio frequencies) it does not necessarily mean that the amplifier's become non-linear in the audio band and that those RF IM products do not necessarily constitute non-linearity in the audio band.
Certainly if the RF is causing the amplifier to become unstable and oscillate, then yes, even the audio band can be boogered up. All I was saying is that's not always the case. You can have RF IM products in the audio band without causing IM or other non-linearity in the audio band itself.
By the way, I note that your reference makes mention of Deane Jensen. As someone who prefers to tell people to go read books rather than offer any enlightenment yourself, perhaps you'd like to go read Deane Jensen's and Gary Sokolich's Spectral Contamination Measurement, AES preprint 2725.
se
"You can have RF IM products in the audio band without causing IM or other non-linearity in the audio band itself."
If you have RF IM products in the audio band it sounds like they are distortion products that don't belong there and attention to RF filtering is desirable.
I will leave it to experts like you to explain RF engineering to the masses. I had to get a degree in engineering, read several books in the last few years, and make a lot of measurements to gain knowledge about RF design, signal integrity, and electromagnetic compliance. I am still learning but you seem to believe you know enough to argue about it. Knock yourself out since you think you know it all. You don't want to learn anything and just want to bluff people that you an expert on everything. I am tired of aguing with people like you. The resources are there for people who want to learn from the experts on the subject instead of reading the rantings of an engineering wanabe.
Have fun,
Fred
If you have RF IM products in the audio band it sounds like they are distortion products that don't belong there and attention to RF filtering is desirable.
I will leave it to experts like you to explain RF engineering to the masses. I had to get a degree in engineering, read several books in the last few years, and make a lot of measurements to gain knowledge about RF design, signal integrity, and electromagnetic compliance. I am still learning but you seem to believe you know enough to argue about it. Knock yourself out since you think you know it all. You don't want to learn anything and just want to bluff people that you an expert on everything. I am tired of aguing with people like you. The resources are there for people who want to learn from the experts on the subject instead of reading the rantings of an engineering wanabe.
Have fun,
Fred
Fred Dieckmann said:
RF engineering? Christ, grab a sense of scale there, Fred. I was simply explaining how shielding shields against EMI.
And after all that you can't explain specifically what the difference is between an equipment chassis that's tied to an actual earth ground and one that's not?
I simply state my understanding of the issue. If my understanding as I've stated it seems questionable to others, then I welcome any evidence to the contrary. However someone simply saying "you're wrong, go read a book" is not evidence. And I'm not going to run around chasing down books and other citations based solely on "you're wrong."
I've been sent on too many wild goose chases in the past so you're going to have to come up with something a little more compelling.
No, I don't think I know it all. Hardly. But I'm not going to acquiesce simply because someone says "you're wrong."
Oh what total crap, Fred.
I'm always willing to learn. And I've never attempted to pass myself off as any sort of expert on anything. Again, I simply state my understanding of things, same as everyone else does. If you've a disagreement with anything I happen to say, then please offer a cogent argument.
Again, "you're wrong, go read a book" is not an argument. So exactly what arguing are you speaking of here?
Hmmm. Well, if you've read those resources and have learned from the experts on the subject, yet you're unable to explain anything you've supposedly learned, then what the hell good are those resources?
And if I read them, will they make me as unable to explain anything on this subject as you and cause me to just tell people they're wrong and go read a book? If so, I think I'll pass, thanks. I prefer resources which increase my understanding and subsequently my ability to explain what I understand so that I don't have to resort to such bluffs as "you're wrong, go read a book."
se
Safety Ground
Hi till,
Safety ground should not be connected to neutral, only to the real ground i.e. the soil. Have your installation checked by a qualified technician. I believe the situation in Germany is not much different from here in Holland. Anyway you should adhere to VDE etc.
till said:
Hi till,
Safety ground should not be connected to neutral, only to the real ground i.e. the soil. Have your installation checked by a qualified technician. I believe the situation in Germany is not much different from here in Holland. Anyway you should adhere to VDE etc.
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Waterpipe Grounding
You are asking me to rationalize irrational, that's impossible. I would have to go back to why in the US they let you build a house on the beach, 5 ft from the atlantic ocean where tides are meters high and where periodically a swell comes and flushes the whole thing in the sea, or to mention your home state, Hollywood hills homes build on pillars, two additional hours of rain the whole house slides down the hill. I guess some american never grasped the deep meaning of the Three Pigs story. I digress.
First the 120V it's the most inefficient way to transport power, high currents, four times RI^2 line losses with respect to the 240V, environmental consequences of increased need for Cu and Al mining etc, etc.
On to the GND discussion: in essence there is no neutral wire, you might as well cut out the third pin from the plug and connect your white wire to the case of your amp, it doesn't really matter.
For audio there maybe consequences of not having a clean GND, because the GND carries all the power harmonic products, I don't know.
This is of paramount importance for safety, I think the choice was made given the fact that the voltage is relatively low and that the houses are made of wood so they are naturally insulating. The only way that the circuit is going to open is that for the live wire to be short to gnd in such a massive way to trip a 15Amps or whatever magneto/thermic protection you have in your fuse box. A person closing the gnd circuit will need much less than 15amps to die.
In Italy but I think in most europe, I m sure the Brits do it differently, we have differential protection, see my earlier post about this, in essence the smallest current deviation between phase and neutral causes the circuit to trip, this is not possible in an american circuit beacuse there is no different path, there is no neutral.
Steve Eddy said:
You are asking me to rationalize irrational, that's impossible. I would have to go back to why in the US they let you build a house on the beach, 5 ft from the atlantic ocean where tides are meters high and where periodically a swell comes and flushes the whole thing in the sea, or to mention your home state, Hollywood hills homes build on pillars, two additional hours of rain the whole house slides down the hill. I guess some american never grasped the deep meaning of the Three Pigs story. I digress.
First the 120V it's the most inefficient way to transport power, high currents, four times RI^2 line losses with respect to the 240V, environmental consequences of increased need for Cu and Al mining etc, etc.
On to the GND discussion: in essence there is no neutral wire, you might as well cut out the third pin from the plug and connect your white wire to the case of your amp, it doesn't really matter.
For audio there maybe consequences of not having a clean GND, because the GND carries all the power harmonic products, I don't know.
This is of paramount importance for safety, I think the choice was made given the fact that the voltage is relatively low and that the houses are made of wood so they are naturally insulating. The only way that the circuit is going to open is that for the live wire to be short to gnd in such a massive way to trip a 15Amps or whatever magneto/thermic protection you have in your fuse box. A person closing the gnd circuit will need much less than 15amps to die.
In Italy but I think in most europe, I m sure the Brits do it differently, we have differential protection, see my earlier post about this, in essence the smallest current deviation between phase and neutral causes the circuit to trip, this is not possible in an american circuit beacuse there is no different path, there is no neutral.
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