Hint: Putting your face up to a 15 x 48 panel is completely different than putting your face up to an 8" cone with a 1" dome. No compare. Sorry.
Hint #2: I normally don't just make stuff up to fill space in forum, so, "yes".
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EMI/RFI thoughts and discussion on its management via cables etc
- Thread starter RogerD
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Hint: Putting your face up to a 15 x 48 panel is completely different than putting your face up to an 8" cone with a 1" dome. No compare. Sorry.
Hint #2: I normally don't just make stuff up to fill space in forum, so, "yes".
Do you speak English?
I have both in the room right now.
The topic is EMI/RFI and Cables. Not your fantasies.
Welcome to the forum Roger. Interesting that you created this thread as it is an area I plan to investigate.
WHen these topics come up, we focus on whether ordinary cables have the problems that high-end cable companies talk about.
We what we don't discuss and seemingly take for granted that should such a problem exist, these cables improve the situation. This will be the focus on my "research." I am pretty confident none-of-these theories have been measured or validated. As such I expect some of them to do nothing to improve things.
Problem is access to these expensive cables. My threshold of pain is a few hundred dollars at most for a high-end cable. If there are some that anyone can volunteer, let me know.
WHen these topics come up, we focus on whether ordinary cables have the problems that high-end cable companies talk about.
We what we don't discuss and seemingly take for granted that should such a problem exist, these cables improve the situation. This will be the focus on my "research." I am pretty confident none-of-these theories have been measured or validated. As such I expect some of them to do nothing to improve things.
Problem is access to these expensive cables. My threshold of pain is a few hundred dollars at most for a high-end cable. If there are some that anyone can volunteer, let me know.
Ask your Friendly Dealer for a Demo.
If they are expensive enough he'll probably come to your house and hook them up to the Analyzer himself so you don't make a boo-boo.
Also, there's this: https://www.thecableco.com/Catalog/Power-Cables
"For our US customers we can offer nearly every cable, powerline product, and resonance control product for in-home evaluation through our famous Library service."
https://www.thecableco.com/category.aspx?cid=-1&mid=-1&criteria=library
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OK, it's no go territory. The point I am trying to make is that competent systems will subjectively sound almost identical, irrespective of the technologies used. Why? Because they must both be producing close to identical acoustic output, otherwise it means at least one is distorting. And listening close up is just like using using a jeweller's eyepiece - the gems look almost identical to casual viewing, but the jeweller easily sees the major differences on close scrutiny.
Again, this is part of the method for achieving convincing sound ...
My friendly dealer is my own company and we don't carry any audiophile cables. I can get eval units from our reps but then don't feel good speaking my mind about them.
I agree and really do not think Walter implied that, assuming he has any sort of engineering or physics knowledge, but that statement can be read that way (or not). I do not know him nor his background. I think the statement was intended to convey the need for a well-shielded cable to prevent RFI from reaching the inner conductor. I think it is a mish-mash of market-speak that obfuscates the real meaning. I don't think RFI is a problem in cheap cables, either, unless very cheap and in the presence of a strong interference field. You can't have current without generating a magnetic field so that in itself is not distortion; if coupled to another signal it may be.
To reduce magnetic interference grounding might not help; you'd need to apply mu-metal shielding or some other ferrous material. Magnetic coupling is usually minor unless you put a low-noise high-gain stage next to a transformer or the incoming power line. Not saying there aren't components like that out there...
As an aside, cables do generate noise, but in the vast majority of cases it is inaudible and buried far, far beneath the noise floor of the active circuits. A while back one of the cable advertisements showed a graph of the noise, but without any sort of units, of course. They showed the thermal noise related to the resistance and showed how their cable had half the noise, without bothering to note their cable simply had half the resistance (it was bigger). Or to note that the noise was many orders of magnitude below perceptibility. Of course, audiophiles are well-known to have ears better than the very best test equipment, cable of resolving noise below the most sensitive leaf voltmeters, etc.
Many years ago there was a movement toward particular cable lengths based upon a misguided application of transmission line theory that also ignored the varying impedance over frequency that most speakers exhibit. The basic science was sound (no pun intended) but totally inapplicable to the application. Monster Cable used to graph frequency response to show how much better their cables were than the competition, again failing to include any units which would have shown just how little it mattered.
Mark this on your calendars: I (mostly) agree with Frank.
I miss Feynman; he had a way of cutting through to the root cause and providing concise, clear descriptions of pretty complex things whether it was quantum physics or grade school textbooks. Years ago one of my friends showed him an audiophile white paper akin to the descriptions above; he proceeded to pick it apart and explain exactly where it went wrong and what they should have said.
It would be something else to have Feynman be involved in these discussions! For those of you who don't know him, he is one of the heroes of Quantum mechanics/Physics.
OK, that second hint wasn't there when I replied - sorry about that. So, subjectively or however you wish to term it, what were the differences?
Don, that would make sense, but if I ignore these factors I don't get optimum sound - I would much prefer to consider that parasitic cable behaviours have no audible impact, but whenever I experiment I find otherwise ... so be it ...
Small cone and Dome - something of a point source radiating into a 1/2 space. The closer you get, the louder it s.
Panel - large radiating area - closer to a line source - but wider - sound level increases at a lower rate as you approach it, and even decreases in very close proximity. As you get close to a point on it, it doesn't get louder - there is barely any sound being generated by one square inch of it - it's the combination of it and the other 719 square inches - most of the sound is being generated where your ear is not when you put your ear to it.
I close my eyes and start walking I can locate the JBL pretty well. You needn't reiterate how "that is the distortion in the JBL" or "you should hear the entire soundfield undisturbed at any point in the room" - I don't buy that.
With the panels, the first time I tried that (years ago) my nose touched it and I thought I was still 3 feet away or so. Now, I'm more used to it, so I'm a better guess.
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Just now, using an SPL meter, TV is the source - commercial inteerruptions:
Listening position / at speaker - not a refined measurement, but...
JBL - 65 / 95
Panel - 65 / 70
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I had a friend move in a new Mac Mini for audio. Nice place on his shelf for it. Of course spent a few days enjoying it as a new audio source. Then found he couldn't listen to records. There was irregular distortion that came and went. Sometimes other weirdness, and he feared his vacuum tube phono pre was going to need a trip back to the maker. Of course it was 3 inches from the PS side of the Mini. On a hunch I turned off the Mini and things were fine though since it was an on/again/off/again problem you couldn't be sure. Turned on the Mini and moved the two pieces right together and got the odd distortion on peaks regularly. So next I engineered a solution. Took a 15 inch long 10 inch wide bit of aluminum foil from the kitchen taped to a notepad. Put an alligator clip on the corner of the foil and the other end of the alligator clip on the ground lug of the pre. Slipped it between the Mini and preamp. Problem solved. Some measurements to 100 khz and it all looked good. Without the shield the Mini was causing some ultrasonic and near sonic oscillation in the phono pre which was then giving it a 50 db boost.
Permanent solution was moving the two pieces a bit over 3 feet apart and all was good. No shield needed. To jump from such things and believe our entire system is in a voracious jungle of EMI/RFI and protecting it improves sound is marketing. Simply moving the pieces apart dropped everything well below the noise floors. Dropping further is something you couldn't have measured and would have heard no benefit from doing.
You can put much larger sources of noise right next to balanced cable and find nothing picked up by it. Single ended IC's yes, though moving 18 inches away is usually enough to drop such effects.
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OK, whether you buy it or not, the "3 feet away still" behaviour is what happens when a conventional box speaker works well. And it's not because the speaker itself has altered, but the quality of the signal driving it. I've switched that subjective behaviour on countless times over the years, on quite a number of, cheap, speakers - the first time it happened it was amazing to hear, but now it's merely the goalposts ...
A standard procedure I do is shut down the entire house electrically - in the extreme I pull all the other fuses in the power box, all mobiles, etc are switched off - the house does nothing electrically except feed the audio system. I listen carefully - and then start switching things back on, one by one, and listen each time ... this has always told me a lot, every time.
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RogerD
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Thank you Amir,
May I suggest you demo a Tripoint or Entreq and then research how those might effect cabling or system quality sound.
These devices peak my interest more and might have a potential larger effect on cabling and the system.
Blumlein 88 said:
Perfect! Computers are among the worst noise offenders around so I'm not really surprised. Shielding as you did is the solution for most computer noise injection ills, especially if you can't move the thing. And the power supply is the section most likely to generate the largest spikes lowest in frequency. That was most likely voltage coupling, however, not magnetic coupling per se. Computers radiate a ton of voltage noise.
One of the big advantages of balanced connections in a high-noise environment is that, unlike a single-ended RCA cable, the outer shield does not carry signal current and so noise coupled into the shield does not directly corrupt the signal. People forget that current is a loop... The shield noise is coupled equally to both sides of the internal wires, to be (hopefully) rejected as common-mode noise by the balanced input stage. One catch is that RFI is not rejected by most audio circuits, balanced or not -- high CMRR is not generally achieved at RF frequencies, or even much above the audio band. Still need RF filters, and/or good RF rejection.
For a little while I piddled with a friend making "audio" computers for professional DAW applications. We added a lot of shielding, both copper screen and mu-metal, adding vibration dampers, swapped fans and reworked cooling (he was an ME and used thermal analysis SW as well as thermal imaging), and in some cases added a Peltier unit to reduce the need for fans (sometimes totally convection cooled with specially-formed heat sinks to carry the heat away). Never made any money at it but it was fun. We went to external sound cards whenever possible; it was a nightmare shielding the internal ones. Another friend worked over the OS and applications to get latency down and reliability up. That magic was mostly beyond my ken...
A lot of folk don't realize fluorescent lights are another big noise source, even when they are working normally. Those little transformers that provide quick starts and clean light without "pulsing" are actually oscillator circuits operating around 60 kHz or so. I learned that years ago whilst trying to track down a noise spike in the lab...
He did borrow an Entreq from Per Olaf and found it to be of no use (well, those are my words).
See the Entreq Thread at What's Best Forum. It seems to have precipitated his expulsion from that Club (and he was a founder)
His report is here, too: http://audiosciencereview.com/forum...ignal-grounding-preliminary-measurements.476/
Part of what's going on, my interpretation, is that it's not possible to hear a high SPL version of the signal with the panel - as Ray says, the radiating surface is spread over a large area, so the sound can't be "concentrated", no matter how close one gets. Effectively, the panel has a 95 - 70 = 25dB advantage in preventing the listener being able to be aware of any flaws in the sound, by the listening more closely techniques. This seems to be part of the 'magic' of panel sound - the poor box speaker has nowhere to hide, if one listens a bit more closely to what it's doing ...
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