John, you yourself might not like this kind of writing as you are a good writer and technical person. But the vast majority of Audiophiles are not technical people, the sound of their system is the most important thing to them. There is a saying that is something like this "write to the level of your readers".
If you don't accept it so be it, I don't think he was writing to someone of your level.
Understood. But you didn't give a practical engineering solution to the problem, if you ever found one? If so, seems like that might have been the most useful part?
It read that way to me. Seemed like you were saying something like, "here, watch me show you how to be technical the right way." Maybe I read differently from what you meant. If so, sorry about that.
I forgot who said it many years ago. When trying to lecture or give presentations to the general public, you have to tailor the level to that of a 6th grader, 13 years old give or take. When giving a tour of a superconducting magnet factory or an x-ray synchrotron machine, it can be so unsatisfying to walk on eggshells trying to make it understandable at that level, but that is what is necessary. An example is bremsstrahlung radiation which creates the x-ray fan , I use a car speeding down the road as a visual.. Fast and straight, the tires are relatively quiet, but turning fast the tires squeal. The electrons "squeal" when they are turned in a magnetic field, and that squeal for an electron is radiation, and that radiation continues along the path the electron had..
The copy you posted was an interesting read, but I don't like the "magic" and "trust me" ad copy. But I also point out good mentions as well.
I was not aware that anybody would be interested in how I solved an 8 encoder cable comms problem over 100 foot long cables in a tray.
The controlled device shall we say, is 3.5 meters long, with encoders at both ends of the device, so the wires create a 3.5 by 2 meter loop, a rather large area. If each cable has their first shield grounded at their encoder, that ground loop picks up stray magnetic fields. The device has four brushless 3 phase motors driving the motion, and also a solenoidal brake at the motor. The biggest problem was the brake solenoids turning off so motion could start. The device design uses steel shafts and couplers, and the brake solenoid is perfectly poised to push magnetic field through the shafting. The return flux loop of the stray is in the air, right where the shield loop can intercept. That induced voltage creamed the dataline voltage levels, sometimes hard enough positive or negative to cause input latchup back at the receiving electronics. Sometimes the readhead would enter a weird data state, sending a position reading that was far from reality, yet the data passed the CRC checks at the receiver. The PID math would instantly send a huge output signal to a motor drive, causing it to lock up and pop it's protection circuitry. The only solution was to walk 1/4 mile, reset breakers, and reboot the system.
The brakes did not have local snubbers, they were 100 feet away., so the turn off transient was a major voltage spike as well as a high rate of change magnetic field.
By isolating the shields off ground at every encoder, the magfield interference fell below the noise immunity levels of the electronics.
It meant ignoring the manufacturers advice, but as I said, their design was meant for one encoder, not multiples. I had to control the stray currents.
I was simply elaborating on his correct statement about shielding with an example. It was not a diss on either the writer of that ad copy, nor Rick.
It is always difficult to read intent when not in person. I did not have mean intent.
jn
With the recent talk about shielding I wanted to share this video about power cord shielding. Paul explains the good and bad of shielding very well. I have heard people talking about not using shielded cable on power amps as it could lessen the dynamics. Now I know that all shielding is not bad from a sonic standpoint.
I was under the impression that Tesla's proposed new type of wireless energy transmission did not involve classical EM radiation, but consisted of what he called "Non-Hertzian Waves".
These "Tesla Waves" would consist of longitudinal standing waves set up in the body of planet Earth, the energy of which could be "tapped into" by consumers across the globe.
The REAL science of non-Hertzian waves is discussed here: https://www.capturedlightning.com/frames/Non-Herzian_Waves.html
Just a little aside, as I'm getting a tad bored of cables! 😉
That’s common in other fields as well, many run to the patent office and actually get published based on their claims.
I stopped the video at 5 minutes in, I just couldn't stand it anymore!!!!
Why do you put this stuff up?
Glad I got that off my chest. Now, read the next bit, then go back and re-watch the video.
Look at the drawings of ground loops I put here what, 14 years ago? I detailed how connecting two pieces of equipment with a line level RCA forming a ground loop with the power cord grounds. I also detailed how the low frequency line level signals prefer to go back to the source by the ground path, NOT by the RCA shielded run. Only when the ground loop impedance has risen high enough will the return signal choose to use the RCA braid.
Before that breakpoint frequency, putting a ferrite over the line cord is actually putting a ferrite over the lower frequency return path. (I cannot stress that enough!!)
The same applies with a full shield, but slightly different. A shield that connects both ends of the line cord changes a large part of the return path impedance, again affecting the return path of the audio signal.
With these concepts in mind, go back and re-watch the video. When he said those things, it all clicks together!! IOW, what he was speaking of has a lot of technical merit but note that he does not try to get overly technical..
While I don't care for the pricing, I have to admit that all the things I build would have very high sticker prices caused by manual labor..mine. I am NOT cheap. Even at 25 cents per hour, nobody can afford me.. I didn't say I was the fastest worker..
Granted, I dislike the adjectives used, like constricting and yada yada, but that's just me.. I need something to complain about, right?
John
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It´s funny to read all the comments on your own Video dissing it, calling it useless snake oil, and plain "shameless plug"
A few pearls, just copypasted from there 🙄
* " I believe it is that shielding the power cord to the amp(s) is in principle unhelpful."
* "Leaning up against a turntable... My father would throw me out of the house and never let me back in. "
* "If messing with your power cord is having an impact on your system’s performance then there’s something grossly wrong with your power supply... "
* "one thing that bothers me is when things that can be precisely understood and measured end up being claimed using vague terms of how it sounds different."
* "Any noise that is emitted or received on a shielded power cable is not audible to me even at low volumes. What frequencies of noise at what point in the signal path doing what can make me hear the effect of a shielded power cable?"
* "An old amp with dried out Vcc filtering capacitors might sound better by using a shielded power cable, but the right cure would be to fix the caps. "
* "I really would have to hear this difference. Can you demonstrate this? Just put a switch on the shield so you can disconnect it while playing a tone. You could do this right on Youtube."
* "It not going to hurt anything to use shielded power cords but they are largely unnecessary. "
* "So what exactly does "constricted sound" sound like? Being that the load impedance is so low and your high grade power supply provides adequate isolation, your just proliferating the myth."
* "Just show measurments on osciloscope with antena (just a meter or two of wire will do) or something."
* "You claim makes no sense."
* "Is the wiring in your walls shielded? Are the big power lines from the power plant to your house shielded? If not, then you are just passing along whatever noise is already there. I guess it can't hurt to have your power cables shielded, but I doubt that it helps, either. "
* ""constrict the sound" huh... i really wonder if there's any of his videos that isn't full of this gut feeling thing. i guess it's his technique of gaining a fan base. easy to understand and conforms to the audience's own gut feelings confirming their preexisting beliefs so they click. he's a salesman after all."
* "paul I really can't see how shielded power cables could affect the sound in any way, the power supply isolates the noise created by the amplifier from mains at the filter caps, plus most high end amplifiers have such low impedance power supplies that none of that matters in the first place."
* " Shameless plug !"
* "Shielding only helps to protect conductors from induced noise and where is this noise going to come from in a listening room?. Most noise will conducted via house wiring due to switching psu's on other electrical outlets, the switching of outlets (in the UK we have switches on our electrical sockets) and via inductive loads from appliances that include motors and pumps. Shielding does nothing to help with conducted noise. "
John, I understand what you are saying about the audio return signal flowing in the safety ground on a power cord. I can see that happening. But what about two wire equipment? I have a Luxman D-03X CD player and it has a two pin IEC connector, no safety ground is used. I use RCA cables with it. I have found it's sound changes with power cord swaps just like three wire IEC equipment does. I have seen digital audio equipment that is only two wire.
I personally prefer the sound of non-shielded power cables. I will not write about how it sounds because you don't want to hear my adjectives. 🙂
There is also capacitance between the power transformer and the hot/neutral.
I always have fun with the adjectives. So many times they convey nothing useful to an engineering discussion.
John
I agree with you Mark, I only use low C split bobbin transformers in my low power equipment. My Luxman CD player has a OI core transformer that I believe is low C pri-sec and the core does not touch the chassis.
Lynn Olson wrote this almost 20yrs ago, I wish he was still writing like this, he has posted here on DIY Audio.
5) Absence of rectifier switching noise. The noisiest circuits of all are solid-state bridges driving large values of electrolytic capacitors. (As found in almost all transistor gear and the DC supplies for heaters and filaments.)
The commutation noise of the diodes shock-excites the RLC of the stray L in the cap bank and the stray C in the power trans secondary. The resonance of this tank circuit is typically anywhere from 4 to 20KHz and the Q's are large, anywhere from 5 to 100, depending on the DCR of the caps. This is why paralleling large values of electrolytics with "better", faster polypropylenes can frequently result in worse sound. It is also the reason power cables are audible ... they act as antennas for the small Tesla coil that most power supplies resemble. The supply radiates noise into the chassis, the power supply B+ lines, the audio circuit, and the power cable. This broadband noise can be filtered and shielded (at considerable trouble), but it is much easier to eliminate the commutation switch-noise right at the source.
Choke-fed supplies are much quieter due to the choke slowing down the rate-of-charge of the main cap bank. I use a hybrid choke-fed/pi-filter to minimize the shock-excitation of the main PS choke (this tip from the Radiotron Designers Handbook, Fourth Edition).
In terms of ragged waveforms, solid-state diodes are the worst, followed by Schottky diodes and HEXFRED's, followed by conventional tube rectifiers, followed by TV damping diodes, which are the smoothest of all in terms of the AC waveform on the power trans secondary. This, along with 2 amp peak current, is why I use them. The 30 second warmup is just a bonus.
5) Absence of rectifier switching noise. The noisiest circuits of all are solid-state bridges driving large values of electrolytic capacitors. (As found in almost all transistor gear and the DC supplies for heaters and filaments.)
The commutation noise of the diodes shock-excites the RLC of the stray L in the cap bank and the stray C in the power trans secondary. The resonance of this tank circuit is typically anywhere from 4 to 20KHz and the Q's are large, anywhere from 5 to 100, depending on the DCR of the caps. This is why paralleling large values of electrolytics with "better", faster polypropylenes can frequently result in worse sound. It is also the reason power cables are audible ... they act as antennas for the small Tesla coil that most power supplies resemble. The supply radiates noise into the chassis, the power supply B+ lines, the audio circuit, and the power cable. This broadband noise can be filtered and shielded (at considerable trouble), but it is much easier to eliminate the commutation switch-noise right at the source.
Choke-fed supplies are much quieter due to the choke slowing down the rate-of-charge of the main cap bank. I use a hybrid choke-fed/pi-filter to minimize the shock-excitation of the main PS choke (this tip from the Radiotron Designers Handbook, Fourth Edition).
In terms of ragged waveforms, solid-state diodes are the worst, followed by Schottky diodes and HEXFRED's, followed by conventional tube rectifiers, followed by TV damping diodes, which are the smoothest of all in terms of the AC waveform on the power trans secondary. This, along with 2 amp peak current, is why I use them. The 30 second warmup is just a bonus.
Oh, come-on;
Fixing that 'problem' has also been a trivial issue, recognised & simply-dealt-with for far longer even (by which I mean 3-4 decades), than before that article was posted.
( I am old enough, at just 50, to remember-when Olsen wrote such guff - and it was nonsense, then)
Fixing that 'problem' has also been a trivial issue, recognised & simply-dealt-with for far longer even (by which I mean 3-4 decades), than before that article was posted.
( I am old enough, at just 50, to remember-when Olsen wrote such guff - and it was nonsense, then)
Its not always fixed. There are always lot of newbies on the forum.
IME even seasoned veterans forget things now and then too.
Would you stop flooding thread with every nonsense you can find on the Internet?
Radiated switching noise is weak and there isn’t a trace of it on any competently designed power supply or amplifier. Sure, it may be that your audio equipment is so problematic that a mosquito fart would change sound. And no, you don’t have that golden ear that can distinguish between sound of copper vs silver plated wire. If you can hear a change from different power cords it’s either delusion or your system has serious ground loops and other issues.
Here are measurements taken on so far used PS, with 1 m power cord and with additional 20 m extension cord coiled on some 25 cm diameter bobbin and placed 30 cm apart from the power supply. That makes an excellent antenna (visible from slightly increased RF noise in MHz range).
Where is that dreadful switching noise? It must be that I don’t have a clue how to take a measurement.
You are invited to show any measurement on your system that shows any difference with different power cords. Then, we can discuss what is the cause and how to rectify that.
What does it look like without the 20MHz bandlimit filter? Also, what is probe bandwidth in 1x mode? ...just wondering 🙂
EDIT: Where is the blue trace probe attached? Thanks!
EDIT: Where is the blue trace probe attached? Thanks!
Used CH2 probe had some 7 MHz bandwidth at 1x. Despite that, noise with 20 MHz bandwidth limiting is lower as noise is picked up by probe cable as well. Red dot depicts measurement STOP state. It is used to get clear measurement snapshot, as trigger point is unstable and point of interest is jumping more than 50 us back and forth.
Here is CH2 with another probe linear to 15 MHz at 1x ratio, no 20 MHz bandwidth limiter and time base which allows for higher HF resolution.
Here is CH2 with another probe linear to 15 MHz at 1x ratio, no 20 MHz bandwidth limiter and time base which allows for higher HF resolution.
Yes I can hear the difference between those kind of wires, if you cannot that is great for you, you just do not have this ability. My system has no ground loops or issues. Power cords make a difference in sound!
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