My imagination, or can a 20 amp circuit make an audible difference? - Page 3 - AVS Forum | Home Theater Discussions And Reviews
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post #61 of 131 Old 10-30-2019, 07:18 PM
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Originally Posted by Glimmie View Post
It certainly can. That doesn't mean it does. Then even if there is leakage, how much is there and how much ends up on the device output terminals in relation to the signal amplitude? As for internal IM, again how much?

I personally find this not to be an issue. It's mainly FUD tactics to sell "audio grade" power filters and outboard power supplies. Most consumer gear has good filtering as they must pass the CE directive to sell in Europe. Unlike our FCC part 15, CE also has standards for EMI/RFI ingress.
Honestly, I never experience sound degradation from noise in the power line, maybe I don't have noise, or maybe I designed my amps with signal integrity and never get affected. Who knows.


Don't count on those CE, UL stamp too much. I lead my group to go to test site to pass CE quite a few times, our major problem was those power supplies that supposedly have CE mark on FAIL and were the source of noise that failed our test I we had to go in and fix their problem. There are 101 ways to cheat, I know!! I was deep into CE testing and all.


Most people think keep wrapping things with copper foil is the fix, but actually that's only the last minute band-aid like in the CE test site. If the device is band-aid from the get go, strange things happen unexpectedly.....at the wrong time. It has to be design correctly from the beginning.


Last but not the least, We fixed and passed the CE test by any ways to get the CE passed, later on, nobody monitor whether we implement all the fixes that passed the test!!! My team passed the test and packed up our bags and left. The production team was left to take everything back and complete that. Whether they followed all the fixes, nobody knows!!!

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Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.

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post #62 of 131 Old 10-31-2019, 12:20 PM
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@alan0354 , so again, thanks for the posts. I still have a failure to..."comprehend" how, however, this isn't easily mediated (in the case of a power amplifier, for sure).

So, let's see if I can put this all in "laymans" terms. I realize that once the HF noise gets into the chasis, through either the signal input or power, it "bounces all over". It also seems that "everything" in the chasis can act something like a HF lightning rod awaiting the noise to "strike". Further, proper design helps mitigate that, and there exists a ton of math to compute how best to design the signal paths to attempt to make them immune.

Having said all that, can't we mitigate the ingress of the EMI? Faraday cages are a thing. If it can't pass from the power supply into the chasis and the power supply isn't compromised in such a way as to allow the power line noise to impact its ability to supply clean power...then...aren't we right back where we started? Well designed power supplies and amplifiers shouldn't be audibly impacted by line noise. I mean, you pretty much said so as much in your last post...which would mean you've always agreed with me, but we had to argue anyway.
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post #63 of 131 Old 10-31-2019, 12:42 PM
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@alan0354 , so again, thanks for the posts. I still have a failure to..."comprehend" how, however, this isn't easily mediated (in the case of a power amplifier, for sure).

So, let's see if I can put this all in "laymans" terms. I realize that once the HF noise gets into the chasis, through either the signal input or power, it "bounces all over". It also seems that "everything" in the chasis can act something like a HF lightning rod awaiting the noise to "strike". Further, proper design helps mitigate that, and there exists a ton of math to compute how best to design the signal paths to attempt to make them immune.

Having said all that, can't we mitigate the ingress of the EMI? Faraday cages are a thing. If it can't pass from the power supply into the chasis and the power supply isn't compromised in such a way as to allow the power line noise to impact its ability to supply clean power...then...aren't we right back where we started? Well designed power supplies and amplifiers shouldn't be audibly impacted by line noise. I mean, you pretty much said so as much in your last post...which would mean you've always agreed with me, but we had to argue anyway.


In short, YES. There is always a way to mitigate the noise problem. One just has to know how.


BUT BUT, as I said, don't count on those established gurus know all these. I have seen the service manuals of many power amps on the market, I know they don't take these into consideration. So the question is if you eliminate all the ones that have problem, you might not have much left to choose from. That's the point we were going back and fore. Yes, you see the problem, this is their problem, there's nothing we can do about it......Unless you want to be like me, design and build my own, then I can say the hell with them!!!


EMI filter is one of the good ways to block the EMI injection through the power cord. That's what OP used, his expensive power conditioner. Still, when you start having USB, DAC, noise comes in from the USB or other digital cable, then you have to fix it differently. There is a lot of virtue of using optical connection. You don't have a ground loop anymore!!!

Also, as I said, what I described is ONE of the usual cause of problem, there are other things that until I have my hands on the amp, I can't even start to speculate. That's why I find this signal integrity so intriguing and keep digging into it. It's fun!!! Go to https://www.hifiengine.com/ Download some service manual and look at their pcb layout. I yet to see one with ground plane and power plane, you can trace how big a loop formed by the signal trace and ground trace. That would be a good antenna loop to receive noise radiation from different sources.

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post #64 of 131 Old 10-31-2019, 01:32 PM
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I want to address about the faraday cage. It's very good for RF shielding, but for audio or even like 40KHz, it might not be effective. This goes back to EM and skin effect. The lower the frequency, the deeper the EM wave penetrate into the metal. In another words, those low frequency noise might pass right through the thin cage as if it's not there. You need thick metal....which make it a lot more expensive and harder to do.


I am giving one obvious example, there as so many not as obvious mistakes that can cause problem that until I can look at the unit, put my hands in it, I cannot even start to talk about problems. Let me give you an example.


I lead my group to bring the instrument to the test site for CE test. One time, we just kept failing the noise emission test, I went over all the shielding and everything over and over. We spent hours on it and couldn't find the problem. Came 2am in the morning, I was so frustrated, I started opening the connectors of the shielded cables that connect between different chassis to make sure all the ground shield are solid even though it measured out right. I found one connector, the shield was connected to the ground of the connector by a 5 or 6in wire instead of very short wire like less than 1in. Apparently the assembler was too lazy to cut the wire short before soldering onto the connector, he/she just stuffed the long wire into the connector housing and closed it up. You measure with a DVM, it's a good connection. Until you open the connector, you would never find out. We fixed that, the system passed the CE with flying color. I really want to kill that person!!! Too bad they were in Mn, out of state!!!


There are so many things that can go wrong, that what make signal integrity so interesting.

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post #65 of 131 Old 10-31-2019, 02:46 PM
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OK, this is going to get complicated. At higher frequencies, you really cannot think of the source in the power station is ZERO. You have to look at the whole thing in Transmission Line Theory. The line is very long from where you are to the station, instead of looking at the source as ZERO ohm, you really see the characteristics of the High and Low line ( the black and white wire in the cable). You have to look at the two lines as PARALLEL LINE transmission line. This is all in Electromagnetic and Transmission Line Theory. In short, the impedance between those Parallel Line Transmission Line is around 90 to 150ohm. Here is the online calculator where you put in the https://cecas.clemson.edu/cvel/emc/c...tor/index.html

You can put in the size of the wire and the wires separation and get the characteristic impedance. So it's not a short circuit at all even the source in the power station is Zero ohm.

I draw two figure representing this.

1) Fig 1 shows the power station, the noise source and the input of a typical amplifier without the EMI filter. As long as the length of the line to the power station is longer than a few wavelength of the noise frequency, you look at the line as transmission line and is typically between 90 to say 150ohm( roughly). Say the noise frequency is 100KHz, the speed of the signal is 186,000 mile/sec, the wave length is 1.86mile. So if you are more than say 3mile from the station, you can count on the line impedance is 90 to 150ohm or so. In practice, even if you are more than a mile away, you use transmission line theory already.
If you introduce noise of 10V into the line, and say the AMP presents a load of 50ohm, even if I use transmission line theory, by the voltage divider shown, you have 3.3V of noise at point A injected into the amp. In real life, the noise source is close to the AMP, the impedance is almost ZERO from the noise source to the AMP, so you have the full 10V of noise into the AMP.

2) Fig 2 shows the same situation except I put an EMI filter in between the line and the AMP. I drew the internal circuit of the typical EMI filter, which is two INDUCTOR(L1 and L2) in SERIES with the power line and capacitor C1 across the two line AFTER the L1 and L2. The impedance of the inductor at the noise frequency is say 200ohm each, so it's 400ohm across the two line on the C1 side. The impedance of C1 (0.1uF) is 16ohm at 100KHz. Using that, the noise voltage at point A is only 0.385V. this show how the EMI filter works.

There is no easy way to explain this, these are all Transmission Line Theory and electromagnetic. You don't look at the source impedance is Zero and it is Zero ohm at the noise source. Hope this helps.
Ok once again you impress us with your electrical engineering studies. Note I said "for all practical purposes" the utility impedance is zero ohms. Of course there is no such thing as zero ohms, ok maybe in a black hole, who knows, I'm sure you have some math for that as well?

The point here is practical engineering. The impedance of the utility what ever it is where you measure it is usually low enough to swap most severe EMI issues. Now a long branch circuit runs will certainly add significant inductance. But unless I am a utility engineer, I don't worry about the impedance of the AC line in my area of work. And I doubt many power supply engineers do either.

And your diagram is way too simplified to get an accurate number. Do you realize how many transformers are in the path between the generator and your wall outlet? How about AC/DC and back conversions on interstate lines. Like I inferred it is simply not possible to calculate the impedance of your AC line feed. Far too many factors you have no control or specification knowledge of.

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post #66 of 131 Old 10-31-2019, 02:57 PM
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In short, YES. There is always a way to mitigate the noise problem. One just has to know how.
And most competent EE's do. But there are other factors beyond just good engineering. You noted a lot of consumer AV gear does not use power and ground planes. OK a 4 layer board in a $59 DVD player?

Again there are practicalities in any field of engineering. Your text books aren't going to explain that well. They assume a perfect world.
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post #67 of 131 Old 10-31-2019, 02:58 PM
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Ok once again you impress us with your electrical engineering studies. Note I said "for all practical purposes" the utility impedance is zero ohms. Of course there is no such thing as zero ohms, ok maybe in a black hole, who knows, I'm sure you have some math for that as well?

The point here is practical engineering. The impedance of the utility what ever it is where you measure it is low enough to swap most severe EMI issues. Now a long branch circuit runs will certainly add significant inductance. But unless I am a utility engineer, I don't worry about the impedance of the AC line in my area of work. And I doubt many power supply engineers do either.
Actually it's not quite true in practical purpose it's zero ohm. There are devices communicate with each other by plugging into the AC power outlets inside the house. They make use of the fact at higher frequency, the power lines are transmission lines and not a short circuit.



https://en.wikipedia.org/wiki/Power-line_communication


https://www.google.com/search?q=devi...w=1396&bih=686

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post #68 of 131 Old 10-31-2019, 03:00 PM
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Originally Posted by Glimmie View Post
And most competent EE's do. But there are other factors beyond just good engineering. You noted a lot of consumer AV gear does not use power and ground planes. OK a 4 layer board in a $59 DVD player?

Again there are practicalities in any field of engineering. Your text books aren't going to explain that well. They assume a perfect world.
We are talking about power amp.

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post #69 of 131 Old 10-31-2019, 03:05 PM
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Actually it's not quite true in practical purpose it's zero ohm. There are devices communicate with each other by plugging into the AC power outlets inside the house. They make use of the fact at higher frequency, the power lines are transmission lines and not a short circuit.



https://en.wikipedia.org/wiki/Power-line_communication


https://www.google.com/search?q=devi...w=1396&bih=686
Right, but these are at higher amplitudes then most line noise. And they are not reliable either.
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post #70 of 131 Old 10-31-2019, 03:07 PM
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We are talking about power amp.
Same issue. Cost versus the magnitude of the problem.
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post #71 of 131 Old 10-31-2019, 03:20 PM
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Right, but these are at higher amplitudes then most line noise. And they are not reliable either.
But that shows it can be done and power lines are treated as transmission line. Those SMPS noise source are very low impedance, they can throw a lot of ***** onto the line. They are known to do that on power lines. These were not a problem 30 or 40 years ago, now, everything use SMPS, all the computers, chargers, communication devices, they all throw ***** onto the lines.

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post #72 of 131 Old 10-31-2019, 03:27 PM
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Same issue. Cost versus the magnitude of the problem.

I think engineers that design DVD players, DAC etc. are a lot more up to date in their knowledge. Power amps are still old school and people that are in it for a long time really never have their knowledge updated. I bet you those design class D amps know what I am talking about, they cannot design class D amps if they don't know how to minimize the switching noise.


I can tell you the Nakamichi PA-7 designed by Nelson Pass and the Acurus 3X200 I have, they are very susceptible to noise, every time we use the microwave oven, turn on the ventilation in the bathroom, the air conditioning, I can hear the noise through the speakers.


BTW, it doesn't cost to do good signal integrity engineering. Just know what to look out. I don't even use EMI filter in my amps.

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post #73 of 131 Old 10-31-2019, 04:18 PM
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I can tell you the Nakamichi PA-7 designed by Nelson Pass and the Acurus 3X200 I have, they are very susceptible to noise, every time we use the microwave oven, turn on the ventilation in the bathroom, the air conditioning, I can hear the noise through the speakers.

I recall noise entering my loudspeakers from a vacuum cleaner and a hairdryer in my folk's house (built in 1929). In my own current house (built in 2002), no noise is ever heard from any device with any of my power amps or other components. Possibly having specified that dedicated pairs of 20A lines be run to both the music and theater rooms is a factor.

Music room: Cary SLI-80 tube integrated amplifier, McIntosh MA6500 integrated amplifier, Quad 99 preamp, Quad 909 power amp, Acoustic Research AR9 loudspeakers, Yamaha CD-N500 CD player, Teac UD-503 DSD DAC, Phase Linear 8000 II linear-tracking turntable.
Theater room: Panasonic 65S60 plasma television; Yamaha RX-A2020 (preamp section); Adcom GFA-5503 and GFA-5400 amplifiers; Polk LSi25, LSiC, and LSiF/X loudspeaker system; Velodyne FSR-18 servo-subwoofer.
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I recall noise entering my loudspeakers from a vacuum cleaner and a hairdryer in my folk's house (built in 1929). In my own current house (built in 2002), no noise is ever heard from any device with any of my power amps or other components. Possibly having specified that dedicated pairs of 20A lines be run to both the music and theater rooms is a factor.

Wiring is really bad in my house, it's a good test ground for amps!!!

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You know, like Power Line Ethernet, which wouldn't work so well if all outlets (on the same phase) didn't share "noise".
Good point. I didn't consider that it would be transferred across what is essentially a star point wiring system.

Now I'm even more paranoid about noise because that means multiple homes are sharing these pole-transformer legs and thus all sharing each others noise...
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Hack, I would not use power line as communication medium period. Just because theoretically it will work, that it's a good idea. You have no control what cable people use, where is the termination. You can have a transformer a block away or you can have it far away. Too many variables.


The point we are talking is you can inject noise into the power line as it's NOT 0ohm impedance that short out all the noise.

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Ignoring lightning strikes for a minute...

Transmission lines are tens of thousands of volts, and are stepped down to residential voltages.

This downscaling and magnetic decoupling reduces most of the utility and industrial noise, no?
The signal-to-noise ratio should be fairly good, no?

and since the pole-transformer and your mains-panel bonds the neutral to earth-ground, wouldn't that mean that most of the noise will be only on the hot legs?

The only exception to that would be an EMP, which travels through the air, striking all wiring with equal force, proportional to its length and surface area. (Hundreds of volts per foot!) This is why NORAD uses 1/2" thick solid metal for its faraday cage on all 6 sides.
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If you're not tripping breakers... no problem.
If you perceive that having other devices on the same circuit as your stereo causes a problem, run a dedicated "stereo only" circuit.
And if you are happy with the new electrical setup, enjoy.
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If there is/was EMI/RFI, ground loop that would present itself as audible noise. Eliminating the offending device(s) will stop the noise.
But, this in reality would not make the amp "sound better" because it has more available power.
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The dehumidifier was the biggest draw, followed by the Anthem integrated. My elliptical has a motorized ramp that uses some juice when elevating. Not sure about the Invisible fence. The other 8-9 attached components are probably a light load, but with everything on at one time, it adds up. Either way, I am glad I ran the extra circuit. If nothing else, I have piece of mind that I am not overloading anything. Did my 2 channel system benefit audibly? Probably not. It just sounds really good to me right now.

This sums it all up IMO.

(without getting subjective, hypothetical, theoretical or evangelical. )



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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post #79 of 131 Old 11-01-2019, 01:57 PM
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Ignoring lightning strikes for a minute...

Transmission lines are tens of thousands of volts, and are stepped down to residential voltages.

This downscaling and magnetic decoupling reduces most of the utility and industrial noise, no?
The signal-to-noise ratio should be fairly good, no?

and since the pole-transformer and your mains-panel bonds the neutral to earth-ground, wouldn't that mean that most of the noise will be only on the hot legs?

The only exception to that would be an EMP, which travels through the air, striking all wiring with equal force, proportional to its length and surface area. (Hundreds of volts per foot!) This is why NORAD uses 1/2" thick solid metal for its faraday cage on all 6 sides.
You are assuming neutral and earth ground are single point. You only have a stick into the ground at one point of the house, then you tie the neutral to the rod. If you wire is 20ft long, the inductance is about 12uH. At 100KHz, the impedance on the other end 20ft away from the grounding rod is 7.5ohm at 100KHz!!! This is no where a short. Noise from switching power supply and inductance kick of electric motor can easily induce noise into the line.

Whether you introduce noise to the hot or neutral line is not important, the noise introduce BETWEEN the hot and neutral lines, that's what is important.

You implied when there is a step down transformer from the HV power line to 110V on the street close to the house will make the line to 0ohm close by to the home. That is absolutely NOT true. Remember the transformer receives HV at the primary, output 110V at the secondary to supply to the house. If the transformer is such low impedance, it will SHORT the primary and burn the HV line. Yes, if you measure the resistance with a voltmeter, you will read 0ohm because the wire in the transformer is big and is 0ohm if you measure with a meter as you measure the DC resistance. Even a 60Hz, it's not even close to 0ohm because the transformer is an inductor.

This is how transformer work, it couple AC through. The output impedance of the transformer is no where 0ohm even at 60Hz. At 100KHz, the impedance must be over 100ohm.

Things are NOT that simple, this is something you cannot explain by simple terms. People don't know science think everything can be explain in simple terms. This is absolute false. Electromagnetic theory boils down to 4 main equation, there is NO EXPLANATION, they are just are. It works, take it or leave it. Don't think those formulas are explained by calculus, actually the Multi-Variable Calculus was invented to explain the formulas, not the formulas explain by the calculus. People think there is an easy way to explain all these are just ignorant.

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post #80 of 131 Old 11-01-2019, 02:20 PM
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Things are NOT that simple, this is something you cannot explain by simple terms. .
They are. Some choose to make this a lesson which wasn't requested.



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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post #81 of 131 Old 11-01-2019, 04:11 PM
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They are. Some choose to make this a lesson which wasn't requested.

You have no idea. It's no point even try to explain to you.

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Its too complicate for you, therefore, I am right, even though I can't explain it, because its too complicated.
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post #83 of 131 Old 11-01-2019, 05:06 PM
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Its too complicate for you, therefore, I am right, even though I can't explain it, because its too complicated.
I explain in detail already, I even put out links. You read them? If you have an easier way to explain the noise induction and why, let me know. I love to read it.

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This is way off the subject and particular for a non technical forum here. All the stuffs we are talking are all electromagnetics that govern by 4 main equation that do NOT have a simple explanation. These are just is, proven by experimental result and in macro world it's accurate.....until someone comes up with a better ones......Just like Newton gravity stuffs are ONLY true in macro world. This is the link to the basic Maxwell's equations ( only 4). This has everything to do with what we've been talking on noise in power line radiating into circuits. There is no other way I know of to explain those noise induction and ways to fix it.



http://www.maxwells-equations.com/


If anyone can explain so layman can understand, I bowl down to you. I spent years studying this and I have yet to find an easy explanation.



I am not trying to brag about my knowledge, it just cannot be explained in simple term, it just is. You'll find there are a lot of things like this when you go into advanced physics. I remember when I was studying Quantum Mechanics, I just cannot really understand because I was expecting to have a simple way to explain it. I kept asking the professor until one day the professor said to me "Alan, you are NOT going to understand it, just keep studying and working on it, one day, you will get the feel of it when you get your PhD." I actual quit Chemistry after I realize that, that a lot of things just DO NOT have explanation and they called it SCIENCE.


When I studied Electromagnetics, I accepted that I am not going to really understand it, just trust it and be good in using the formulas.


BTW, watch the video in the link, that's a very good explanation, much much better than I can give. See whether it is more comforting!!!!

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Noise is a commonly known element in circuits. The causes of noise are well known. Noise is measurable and there are plenty of proven methods to reduce it. You don't even have to know anything about Maxwell's Equations to deal with it, just troubleshoot known causes and/or find and implement already designed solutions.



Its not that complicated. Its not mystical force and only the enlightened can deal with. You can complicate it with poor description, and you can describe it in way that makes it sound like you have some expertise or understanding. And, you can 'study' something and still not understand it, it doesn't mean it is too complicated and nobody can understand it... like chemistry.


I have a degree in EE, I understand electromagnetics quite well. The stuff you say is, in technical terms, is what is officially known as "gobbledygook". Linking to a page of equations you can't explain to show you know more than others is an interesting tactic though.
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The proverb 'A little knowledge is a dangerous thing' expresses the idea that a small amount of knowledge can mislead people into thinking that they are more expert than they really are, which can lead to mistakes being made.



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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post #87 of 131 Old 11-02-2019, 10:21 AM
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The proverb 'A little knowledge is a dangerous thing' expresses the idea that a small amount of knowledge can mislead people into thinking that they are more expert than they really are, which can lead to mistakes being made.

You should credit your source if you are going to make a direct quote:

https://www.phrases.org.uk/meanings/...ous-thing.html
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Oo-o-o-o-o.... sorry!

My bad. I should be careful in the future. Thanks for taking out the time to investigate my blatant faux pas.



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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post #89 of 131 Old 11-02-2019, 10:52 AM
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Originally Posted by DanPackMan View Post
Noise is a commonly known element in circuits. The causes of noise are well known. Noise is measurable and there are plenty of proven methods to reduce it. You don't even have to know anything about Maxwell's Equations to deal with it, just troubleshoot known causes and/or find and implement already designed solutions.



Its not that complicated. Its not mystical force and only the enlightened can deal with. You can complicate it with poor description, and you can describe it in way that makes it sound like you have some expertise or understanding. And, you can 'study' something and still not understand it, it doesn't mean it is too complicated and nobody can understand it... like chemistry.


I have a degree in EE, I understand electromagnetics quite well. The stuff you say is, in technical terms, is what is officially known as "gobbledygook". Linking to a page of equations you can't explain to show you know more than others is an interesting tactic though.
Did you follow the discussion, the discussion was why, not how to fix it.

Read through the debate and discussion in this thread. I would love to hear from you explaining the question asked in simple form. I am open to learn.


BTW, since you understand electromagnetics really well, can you teach me how to explain the 4 equation in very simple layman term? I really open to learn.

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post #90 of 131 Old 11-02-2019, 10:56 AM
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Oo-o-o-o-o.... sorry!

My bad. I should be careful in the future. Thanks for taking out the time to investigate my blatant faux pas.
I take that you really understand what we are talking about. You should put in your reasoning, I love to hear it, maybe I can learn something the book didn't show.

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