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  1. #1
    Forum Regular Chuck's Avatar
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    Have these articles been discussed previously?

    This article appeared in the JAES so one assumes that it was properly peer reviewed before publication.

    http://bruce.coppola.name/audio/cableInteractions.pdf

    The second piece takes a more negative view, but is consistent with the above (note the magnitude of the differences measured in the first paper).

    http://bruce.coppola.name/audio/TenAudioLies.pdf

    Since both are PDF files it may be easier to download them and read them off-line.

  2. #2
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    Quote Originally Posted by Chuck
    This article appeared in the JAES so one assumes that it was properly peer reviewed before publication.

    http://bruce.coppola.name/audio/cableInteractions.pdf

    The second piece takes a more negative view, but is consistent with the above (note the magnitude of the differences measured in the first paper).

    http://bruce.coppola.name/audio/TenAudioLies.pdf

    Since both are PDF files it may be easier to download them and read them off-line.

    I do cite the Davis paper when called for. Yes, it is a Journal paper, not a conference paper and was peer reviewed. A great find on line. I am not sure it is leagl though.

    The second is cited by others from time to time but now you found that on line as well.
    mtrycrafts

  3. #3
    Forum Regular Chuck's Avatar
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    Quote Originally Posted by mtrycraft
    I do cite the Davis paper when called for. Yes, it is a Journal paper, not a conference paper and was peer reviewed. A great find on line. I am not sure it is leagl though.

    The second is cited by others from time to time but now you found that on line as well.
    I can't take credit for either find. Both came from GDS.

  4. #4
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    Quote Originally Posted by Chuck
    I can't take credit for either find. Both came from GDS.
    Unfortunately, about the only discussion that will occur on this board is cheerleading, as both articles are really just preaching to choir here.

    Too bad there isn't a place they could be critically reviewed by knowledgeable people who don't have a particular agenda to advance.

    I'm not technically qualified to discuss either article. However, the second one seems to just be a collection of broad generalizations in the form of absolute pronouncements which I don't find particularly helpful. All one needs to do is go over to AA and easily find someone who can shout just as loud in the opposite direction.

    I subscribed to Audio Critic back in the days with Mr. Aczel was an unabashed subjectivist. In fact, I followed his suggestion on a turntable and arm and was very satisfied with the result. However, as I recall, it was later discovered that he was favorably reviewing a speaker that he had an undisclosed business interest in.

    He shut down Audio Critic, and went into producing speakers full time. As I recall there were still several issues remaining on my subscription for which I never received a refund.

    At some point, God paid him a visit and he was magically transformed into his current objective manisfestation.

    The foregoing is just my personal opinion and and vague historical recollection, which could be flawed.

    BTW, on the first article, as I understand it he did not test complex waveforms and possible distortion, including temporal distortion. Am I correct and do you think such tests should be performed?

  5. #5
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    Quote Originally Posted by pctower
    Unfortunately, about the only discussion that will occur on this board is cheerleading, as both articles are really just preaching to choir here.

    Too bad there isn't a place they could be critically reviewed by knowledgeable people who don't have a particular agenda to advance.
    Can you produce anything better? Didn't think so.
    "Opposition brings concord. Out of discord comes the fairest harmony."
    ------Heraclitus of Ephesis (fl. 504-500 BC), trans. Wheelwright.

  6. #6
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    Two disappointing articles

    I must say I was quite disappointed with both articles. The first article treated speaker wires mathematically as the lump sum parameter equivalents of distributed parameter linear filter networks. As I have said all along, if this is the best case that cable advocates can make then they have no case at all. ALL linear (frequency response) distortion due to inductance, capacitance, and resistance of the cable interacting with the speaker and amplifer can be compensated for by adding complimentary filters at any signal level but preferably at the preamp level using an adjustable equalizer is by far the best because it can be infinitely adaped to any situation. Because the degree of filter effect of any wire will not only depend on the nature of the wire but its length and the complex impedences of both the amplifier output stage and the loudspeaker it is connected to, unless you are an engineer, it is impossible to predict in advance how the cable will affect the sound and if it has any audible effect at all, what creates an improvement (meaning flatter overall frequency response) in one system may cause a deterioration in another. There were NO DBTs to back up the conclusions, no control using duplicate setups with filters simulating wires, no complex waveform analysis and absolutely no discussion of non linear distortion. We heard much of nonlinear distortion without evidence form people like Jon Risch here (digital jitter and insulation induced memory) and John Curl at CA (Fermi velocity and the difference of -120db versus -135db seventh harmonic distortion of a 5 khz waveform.) There are as many others as there are cables for sale.

    The second article was all about well known myths that audiophiles love to to use to challenge electrical engineering facts. About the only thing there to take issue with is number 10 as it is obvious that the level of auditory accuity varies from individual to individual, mostly the self appointed "golden eared" audiophiles having poorer auditory accuity having exposed themselves to loud rock and roll at live concerts and with their very loud sound systems at home and in their cars. In fact, like most other senses, you can be trained (usually fairly easily) to become more discriminating to the differences of different sensations you experience which you would otherwise overlook so you can become more attuned to auditory differences but this is a matter of mental concintration than of more accute sense organ sensitivity.

  7. #7
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    Too bad there isn't a place they could be critically reviewed by knowledgeable people who don't have a particular agenda to advance.

    Well, Davis had a critical review before publishing in a Journal.

    However, the second one seems to just be a collection of broad generalizations in the form of absolute pronouncements which I don't find particularly helpful. All one needs to do is go over to AA and easily find someone who can shout just as loud in the opposite direction.


    Yes, they can shout without evidence. Peter and Dr.David Rich, his technical person at TAC has been doing DBT from the day he saw the light. That is what converted him, not God.[/b]

    At some point, God paid him a visit and he was magically transformed into his current objective manisfestation.

    Actuall, it was sanity, reality that transformed him.

    .

    BTW, on the first article, as I understand it he did not test complex waveforms and possible distortion, including temporal distortion. Am I correct and do you think such tests should be performed?



    You think wires will react to complex waveforms differently? I'd like to see the evidence for that. Same for temporal distortion that jneutron is so fond of. Skin effect delays some of the frequency arrival times, in the nano second timescale:
    "Amplifier-Loudspeaker Interfacing", Greiner, R.A., JAES vol. 28, no. 5 May 80,
    I think he is confusing the ability to spacially locate sound sources that require the same frequency to arrive at the left and right ear at different times and shift in the frequency itself in the same cable. Having two cables in the left and right channel would delay the frequency equally in each cable hence no time difference between the two channels, unless you have 1000s of feet of wire differencesin one channel. But, hey, I have no idea.

    If you followed Steve Eddy's wire distortion reports and discussions, there is no measured distortion from wire. Signal complexity in the audio band will not change that.
    mtrycrafts

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    [QUOTE=mtrycraft]Well, Davis had a critical review before publishing in a Journal.

    So why did Chuck ask for discussion if there is absolutely nothing to question?

    I've got a serious question for you. Do you universally accept as reliable any test where the results confirm your beliefs? Do you see any value in questioning test results that seem to confirm mainstream beliefs? If your answer to is no to the first question and yes to the second one, I must say that you have never as far as I'm aware demonstrated any behvior on this board that would be consistent with such an answer.

    While we are at it, do you claim to be objective on the subject of cables?

    [You think wires will react to complex waveforms differently? I'd like to see the evidence for that. Same for temporal distortion that jneutron is so fond of. Skin effect delays some of the frequency arrival times, in the nano second timescale:

    How would I know. Chuck asked for some discussion.

  9. #9
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    Quote Originally Posted by Pat D
    Can you produce anything better? Didn't think so.
    Yeah, like I observed over at Prophead recently, this is all about tribes. It just depends on whether you want to hang out in naysayer territory or yeasayer territory. In either case, the objective of the tribe you choose to hang with is to destroy the other tribe.

    If you want to delude yourself that this board is a place where there is a good exchange of opposing views and information based on a desire for the truth, and where all claims and "evidence" is subjected to critical analysis, then be my guest.

  10. #10
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by mtrycraft
    You think wires will react to complex waveforms differently? I'd like to see the evidence for that.
    You've got that bass ackwards. Perhaps you listen to test tones, but I think it is fair to say that most folks enjoy listening to music (aka complex waveforms). It is your camp that begins with the assumption that there will be no difference with tests on simplistic wave forms vs. that which is used in the real world.

    The burden of proof is yours to substantiate that assumption. History is not on your side as the value of the time domain has been proven over and over again. Do you recall how worthless THD measurements were rendered once TIM was established? Do you recall how worthless most specifications were on the "perfect sound forever" digital players prior to the understanding of jitter?

    rw

  11. #11
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    Nature abhors a vacuum

    Quote Originally Posted by E-Stat
    Do you recall how worthless most specifications were on the "perfect sound forever" digital players prior to the understanding of jitter?
    rw
    Nature abhors a vacuum. At least that's what they say. Of course if you look at the universe as a whole, more than 99.9999% of it is empty space, ie a vacuum. But that's what they say. I was wondering who would take up Jon Risch's arguements now that he no longer seems to want to grace us with his wisdom even occasionally. And digital jitter created by installing the wrong wires was certainly one of his causes. Yes somehow the entire time domain, the master clock of the universe gets screwed up by these wires and your stereo system can never reverse time and straighten out the mess. No amount of reason or arguing could persuade him otherwise. No matter how many times I told him that when the signal came in it was reclocked by a schmidt trigger or that the buffer registers dumped into a register that reclocked them could convince him. Of course the coup de grace came when I pointed out that the jitter caused by the wow and flutter of the spinning disc was many orders of magnitude greater, perhaps millions of times more than the jitter caused by the cables. So he invented the notion of fast jitter and slow jitter but I don't think he even convinced himself of that. It was shortly after I exploded all of his absurd explanations that he stopped coming around. I miss him. Like I miss a toothache. Care to take up the challlenge of defending his point of view E-stat?

  12. #12
    Forum Regular Chuck's Avatar
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    Quote Originally Posted by pctower
    BTW, on the first article, as I understand it he did not test complex waveforms and possible distortion, including temporal distortion. Am I correct and do you think such tests should be performed?
    The author makes the assertion that the electrical characteristics of the wire, amp, and loudspeaker, will determine the ultimate performance, and then proceeds to measure the electrical characteristics, along with their effects on the performance. If the assertion is true, then his measurements are sufficient. As a result I think your question is actually aimed at his assertion rather than his measurements. Aren't you really asking if there isn't more to cables than just the electrical parameters?

    Certainly there are many alternate ways to measure just about anything, and it only makes sense to use the appropriate tool for the job. If we had reason to believe that commonly used speaker wire configurations are distorting the signal in some way not revealed by conventional static measurements then it would make since to investigate further. It is rare to see anything in the complex transfer function of a circuit that isn't predicted by the electrical parameters. When it does happen it just means that we've overlooked some parameter. If you're asking if I'd have done things differently, the answer is a resounding YES. After going to all the trouble to set up the equipment for the test I'd certainly have run and recorded MLS tests for later analysis, and I'd have measured the complex transfer function of every wire/speaker/amp combination. I would not, however, expect any of these tests to show anything that wasn't indicated by relevant electrical parameters. In other words, I think electricity obeys the laws of physics. We sometimes overlook factors in our circuit analysis, so I tend to over-do my own measurements. The author is probably much smarter than myself in this respect.

    Phil, did you notice that none of his measurements showed as much as a full dB of loss at 20k, and never enough phase (temporal) shift to be suspect? Do you know of anyone, other than me, who has measured a wire induced anomaly greater in magnitude than what is presented in this JAES paper? I've measured 2dB at 14k, but can you point to ANY other tests of ANY kind that that show greater problems in typical wire configurations? I'm not aware of any, so if they exist I'd appreciate a few links.

    What exactly do you think the author (and the AES peer review) overlooked?

  13. #13
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by skeptic
    Of course the coup de grace came when I pointed out that the jitter caused by the wow and flutter of the spinning disc was many orders of magnitude greater, perhaps millions of times more than the jitter caused by the cables.
    Who said anything about the contribution of wires to jitter?


    Quote Originally Posted by skeptic
    Care to take up the challlenge of defending his point of view E-stat?
    Without knowing his point of view, I am unable to defend it. What is it exactly? Are you of the opinion that the earliest CD players, despite their "wonderful (static) measurements" did NOT sound absolutely dreadful? If not, then I banish you to listening to my 1988 Magnavox unit to eternity. When the knowledgeable press began reporting that the emperor was stark naked, then the (best) engineers started to reconsider some of their assumptions. Gee, our initial testing methodology wasn't exactly sufficient. Duh.

    My observation is that static measurements of audio components designed to reproduce musical content have been repeatably proven to be of zero value in determining what the most discriminating listeners have consistently observed to be true. The engineers eventually figured out how to measure those observations. That is an easy position to defend.

    rw

  14. #14
    Forum Regular Chuck's Avatar
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    Quote Originally Posted by pctower
    How would I know. Chuck asked for some discussion.
    Actually, I asked if it had been discussed, and that question was answered in the very first response. I can see that some like the articles and some don't, and that both opinions are being expressed, so I don't understand why you feel that there is no open discussion here. I personally found the discussion of the character and motives of the authors to be rather interesting.

  15. #15
    Forum Regular Chuck's Avatar
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    Skeptic, I'm sorry to hear that you were so disappointed, but as we can see in the responses above, the articles actually generated some lively discussion. It's interesting that for once (is it the first time ever?) you and PCTower agree on something. Neither of you liked the articles very much.

  16. #16
    Forum Regular Chuck's Avatar
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    Quote Originally Posted by pctower
    So why did Chuck ask for discussion if there is absolutely nothing to question?
    Phil, I don't think Mtrycrafts is qualified to answer that question.

    I am qualified to answer it, but my answer will probably sound stupid. I asked if the articles had been discussed because (surprise) I wanted to know if they had been discussed.

    Skeptic doesn't like the paper because he feels that it supports exotic cables. You seem to think it trash as well. So I guess at least we have finally found something about which you two can agree.

    I see the JAES paper differently. It is a peer reviewed paper that confirms my own findings and understanding, so naturally I like it, even if I don't agree with every statement or conclusion. Since it is a peer reviewed paper that was published in a professional journal it takes more than contempt to make it go away. If the work is flawed, we correct it by exposing the flaw. Where is it? The AES found no reason to reject the findings. Do you feel that your knowledge and ability to judge this article is superior to theirs? (That is apparently the way Skeptic feels, so you two any agree on two things.)

    Phil, it's like all such work. It proves only what it proves, and nothing more. Sometimes not even that, but as it is, there is no flaw in the methods that has been made apparent. What have I (and the AES) missed?

  17. #17
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    Quote Originally Posted by Chuck
    Skeptic, I'm sorry to hear that you were so disappointed, but as we can see in the responses above, the articles actually generated some lively discussion. It's interesting that for once (is it the first time ever?) you and PCTower agree on something. Neither of you liked the articles very much.
    I was disappointed because these articles are so old as to be trite already. I expect more from JAES than the umpteenth rehash of old well worn ideas. Yes every electrical engineer knows all about LCR networks, distributed parameter models of wire and their lumped sum equivalents, how to analyze them and has made up his mind a long time ago one way or another whether a few tenths of a db difference at 20khz can make an audible difference, and whether it's worth hundreds of dollars to get it. It seemed like the writer was looking for something to publish with his name on it. Anything to publish with his name on it. It's high time that at a professional level, the debate moves much further along and delves much deeper if someone wishes to engage it at that level.

    As for the second article, it was a consumer directed article which also rehashed old ideas for the umteenth time. And while it may come as a surprise to many newcomers that anyone would challenge the prevailing notions among audiophiles that tubes are better than transistors, vinyl phonograph records are better than cds, audiophile wire is important, and the sales people who have capitalized on these notions to the point where they will sell $500 worth of cables to someone who is buying a $1000 HT system, these issues were resolved a long time ago also by electrical engineers and audio engineers who buy and use this kind of equipment for a living and where cost often is less of a consideration than performance. And while engineers also like to get nostalgic and revisit the masterpieces of yesteryear, they have no doubts about what they have to buy or use when it comes to competing in the real world. Yes a 1963 Corvette will outperform a 2003 Toyota Corolla but not a 2003 Corvette. Technology does move forward, like it or not.

  18. #18
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    Quote Originally Posted by Chuck
    The author makes the assertion that the electrical characteristics of the wire, amp, and loudspeaker, will determine the ultimate performance, and then proceeds to measure the electrical characteristics, along with their effects on the performance. If the assertion is true, then his measurements are sufficient. As a result I think your question is actually aimed at his assertion rather than his measurements. Aren't you really asking if there isn't more to cables than just the electrical parameters?

    Certainly there are many alternate ways to measure just about anything, and it only makes sense to use the appropriate tool for the job. If we had reason to believe that commonly used speaker wire configurations are distorting the signal in some way not revealed by conventional static measurements then it would make since to investigate further. It is rare to see anything in the complex transfer function of a circuit that isn't predicted by the electrical parameters. When it does happen it just means that we've overlooked some parameter. If you're asking if I'd have done things differently, the answer is a resounding YES. After going to all the trouble to set up the equipment for the test I'd certainly have run and recorded MLS tests for later analysis, and I'd have measured the complex transfer function of every wire/speaker/amp combination. I would not, however, expect any of these tests to show anything that wasn't indicated by relevant electrical parameters. In other words, I think electricity obeys the laws of physics. We sometimes overlook factors in our circuit analysis, so I tend to over-do my own measurements. The author is probably much smarter than myself in this respect.

    Phil, did you notice that none of his measurements showed as much as a full dB of loss at 20k, and never enough phase (temporal) shift to be suspect? Do you know of anyone, other than me, who has measured a wire induced anomaly greater in magnitude than what is presented in this JAES paper? I've measured 2dB at 14k, but can you point to ANY other tests of ANY kind that that show greater problems in typical wire configurations? I'm not aware of any, so if they exist I'd appreciate a few links.

    What exactly do you think the author (and the AES peer review) overlooked?
    No Chuck, I'm asking exactly what I asked and I didn't mention his assertion. Again, I'm asking whether conducting a test under similar conditions, but measuring distortion characteristics of the waveform, including temporal distortion, could possibly have yeilded different results? Stated another way, is it possible to extrapolate from his tests that measurement of waveform distortion would show nothing of use that was not shown in his test? I think what you are saying is that there is no need to measure waveform distortion. Somehow, though, that doesn't make intuitive sense to me.

    What do I think they overlooked? Possibly waveform distortion. That's why I asked the question. Why do you have to turn that question into something it is not. That's a Jon Risch trick, who would far rather discuss naysayers and yeasayers than technical issues..

  19. #19
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    Quote Originally Posted by skeptic
    I was disappointed because these articles are so old as to be trite already. I expect more from JAES than the umpteenth rehash of old well worn ideas. Yes every electrical engineer knows all about LCR networks, distributed parameter models of wire and their lumped sum equivalents, how to analyze them and has made up his mind a long time ago one way or another whether a few tenths of a db difference at 20khz can make an audible difference, and whether it's worth hundreds of dollars to get it. It seemed like the writer was looking for something to publish with his name on it. Anything to publish with his name on it. It's high time that at a professional level, the debate moves much further along and delves much deeper if someone wishes to engage it at that level.

    As for the second article, it was a consumer directed article which also rehashed old ideas for the umteenth time. And while it may come as a surprise to many newcomers that anyone would challenge the prevailing notions among audiophiles that tubes are better than transistors, vinyl phonograph records are better than cds, audiophile wire is important, and the sales people who have capitalized on these notions to the point where they will sell $500 worth of cables to someone who is buying a $1000 HT system, these issues were resolved a long time ago also by electrical engineers and audio engineers who buy and use this kind of equipment for a living and where cost often is less of a consideration than performance. And while engineers also like to get nostalgic and revisit the masterpieces of yesteryear, they have no doubts about what they have to buy or use when it comes to competing in the real world. Yes a 1963 Corvette will outperform a 2003 Toyota Corolla but not a 2003 Corvette. Technology does move forward, like it or not.
    Well, I find it strange that you would put Fred E. Davis in the cable camp! His conclusions do not support that. He does point out that 12 AWG wire performs very well, well enough.

    I also see nothing in Peter Aczel's article which denies the efficacy of training. The Audio Critic is a consumer magazine so it is appropriate that it counterbalance some of the audio misinformation which abounds in many other magazines.
    "Opposition brings concord. Out of discord comes the fairest harmony."
    ------Heraclitus of Ephesis (fl. 504-500 BC), trans. Wheelwright.

  20. #20
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    Quote Originally Posted by Chuck
    Skeptic, I'm sorry to hear that you were so disappointed, but as we can see in the responses above, the articles actually generated some lively discussion. It's interesting that for once (is it the first time ever?) you and PCTower agree on something. Neither of you liked the articles very much.
    Chuck - please stop putting words in my mouth. I thought the first article was good. I just questioned whether more work needed to be done. Is that an inappropriate question in engineering or science circles? If it is, I can't imagine how science ever progresses.

    As to the second article, you are correct that I didn't particularly care for it, but I stated specific reasons - primarily that it seemed to contain a number of unqualified pronouncements backed up with little empirical or reasoned support. I also shared my recollection of the author's history.

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    Quote Originally Posted by Pat D
    Well, I find it strange that you would put Fred E. Davis in the cable camp! His conclusions do not support that. He does point out that 12 AWG wire performs very well, well enough.

    I also see nothing in Peter Aczel's article which denies the efficacy of training. The Audio Critic is a consumer magazine so it is appropriate that it counterbalance some of the audio misinformation which abounds in many other magazines.
    What I said about the first article is that it retraces old ground that has been trod into a ditch already. At that level, I expect something new but this guy was much to lazy or ill equipped to offer it. He did not offer one technical fact that any electrical engineer already doesn't know except for the measurements of specific wire. It's about time the engineering pros take a much harder and in depth look at the whole question meaning accuracy of reproduction of real waveforms using computerized analysis seeking non linear distortions and DBTs to back up their findings. In 1984 this might have been a little new. In 2004 it's kindergarten.

    I'm not quite so critical of the consumer article in that it merely rehashes what the overwhelming majority of electrical engineers and professional audio engineers know and agree with. I suppose it is useful to reprint these once in a while even though most beginners will take their cues from audiophiles who don't believe a word of it and they of course will scoff at all of it. However, we've been there, done that a million times too so it's rather boring to read it again.

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    Quote Originally Posted by mtrycraft
    You think wires will react to complex waveforms differently? I'd like to see the evidence for that. Same for temporal distortion that jneutron is so fond of. Skin effect delays some of the frequency arrival times, in the nano second timescale:
    yes, I would also like to see evidence for that..I certainly have none at this time..

    Skin effect on sines is in the 250nSec regime, from what I recall..not what I hypothesize.
    What I am hypothesizing is the change in energy storage, not something as simple as group delays..

    Where that stands now? Glad you asked..

    I am wrestling with my model, and how it stands w/r to superposition. As in, does my model break down in regard to multiple signals each at different skin values...can the resultant be equally described by the sum of the signals, or does my slew rate model break down...still lots of work to do before I can really test it..

    Cheers, John

  23. #23
    Forum Regular Chuck's Avatar
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    Quote Originally Posted by pctower
    No Chuck, I'm asking exactly what I asked and I didn't mention his assertion. Again, I'm asking whether conducting a test under similar conditions, but measuring distortion characteristics of the waveform, including temporal distortion, could possibly have yeilded different results?
    My point was that if the assumptions were false then the conclusions were suspect, and while I don't want to beg the question, I think that is exactly what you're asking. HIS assumption was that the answer to your question is a resounding "no." His conclusions are based on an assumption that you are now questioning, and the question seems valid to me. The relationship between his assumptions and your questions does little to answer the question about additional tests, so let's just not worry about that (it's not really important) and focus on the questions you've asked. In an earlier post you feigned some degree of technical incompetence, so in spite of the fact that I think you're more technically competent than you let-on, I'm going to take the approach I'd take with someone with absolutely no technical background. Those who don't like longer posts might want to move on to the next post in the thread.

    We actually need to discuss testing in-general. The very reason we have different ways to test things is because different tests tell us different things. Meters are handy for measuring steady-state or slowly changing values, and for those cases where we apply averaging in one form or another. For more complex events we learn more by using equipment that records values over time. The simplest and most common of these is the oscilloscope. Originally all scopes used the persistence of phosphor to "record" signal amplitude over time. This is the most common of all dynamic signal measurements and is in fact a time domain measurement. We can actually do quite a lot with the simple time/amplitude trace produced on a simple scope. With patients and a calculator we can even perform transforms and use a spreadsheet to plot the displayed waveform in the frequency domain. There is actually nothing to measure other than amplitude over time. "Amplitude" in this general context refers to any amplitude that we might be measuring, whether it be voltage, velocity, force, or anything else that can produce a complex modulation. With a scope only, the signal complexity quickly becomes too complex to deal with, so we have other tools that automate the process(es). We capture amplitude data in the time domain, and transform it to the frequency domain using a variety of methods (FFTs being the most common). A "frequency response plot" is the plot of amplitude vs. frequency instead of amplitude vs. time, so it's a frequency domain measurement. It is probably worth noting that both measurements are based on the same physical measurement, that being the amplitude of some event over time. Now if we're looking for harmonic or IM distortion we might be able to see it in our frequency domain measurements. If of sufficient magnitude, the extra energy produced as distortion products just *might* stick out like a sore thumb. However, when the distortion levels are low this just won't work. As a result, we stimulate the device under test (DUT) with a known signal, and then examine the output products that were not present at the input. Early THD and IM measurements used single tones for THD and dual tones for IM. Using pseudo-random noise and FFT's allows us to plot frequency domain measurements as quickly and easily as we plot time domain measurements on a scope, and it can't be denied that these measurements quickly expose audible differences. That's not to say that they expose all audible differences however or that it is even a good way to look for certain distortion products. Not all frequency response plots use noise. Some sweep a tone across the bandwidth of interest. In every case I've seen the sweep response and noise response curves are, for all practical purposes, identical. Be that as it may, there are still more telling ways to measure things. Today we use MLS (for "Maximum Length Sequence"). Here our test stimulus is deterministic, and can be tailored to whatever spectral content is most appropriate for the particular measurement. Amplitude data is measured in the time domain, as with all other measurements, and can then be scaled and compared to the original stimulus. Any difference between the stimulus and the measured response has to have come from something in the signal path. While we can look at the transfer function of a DUT using a scope, MLS lets us look at the transfer function in the frequency domain. We can also determine the true phase, with or without group delay, and measure harmonic and inharmonic distortion content in both the time and frequency domain. We can do impulse plots, spectral decay plots, phase plots, and so on, in both the time and frequency domains, all from a single measurement. An MLS can be created to mimic the characteristics of various types of music and other "natural" events, and it's a quick and easy way to measure the important characteristics of an audio device.

    Now your question seems to be whether or not we can predict the results of something like an MLS test based on the measurements presented in the JAES paper. Certainly that is not outside the realm of possibility. We might also find life on Mars, but never having been there I wouldn't hazard a guess. I test with MLS and other simpler methods, and the results are consistent. Yes, if we were to measure the complex transfer function of the wires under the same conditions we would, ABSOLUTELY and without a doubt, see some things that we don't see in the tests done to support the paper, but there is every reason to believe that all of them would be of such small magnitude that they'd be of no consequence. If that weren't the case you can probably be sure that someone on the JAES review panel would have demanded more tests.

    What we have is an article that asserts that a certain group of tests is sufficient. While the group of tests would not be sufficient in all cases, there is no reason to believe that they are not sufficient in this particular case and application. All the measurements and conclusions are consistent with our understanding of physics and EM theory, so on face value they are reasonable and seem correct. Obviously the JAES review board agrees. If there are some undiscovered things taking place in some speaker wire then somehow nobody has ever managed to expose it in any measurement or controlled test, so nobody other than Jneutron is going to waste their time chasing ghosts. With respect to Jneutron, it's a dirty job, but apparently someone has to do it, and he seems to be the right man for the job.

    Quote Originally Posted by pctower
    Stated another way, is it possible to extrapolate from his tests that measurement of waveform distortion would show nothing of use that was not shown in his test? I think what you are saying is that there is no need to measure waveform distortion. Somehow, though, that doesn't make intuitive sense to me.
    I certainly didn't say that there was no benefit in measuring waveform distortion. Nobody bothers more than a few times because there isn't enough waveform distortion in wire to worry about. Wire has a fraction of the distortion of the best amplifiers, and the best amplifiers don't have enough waveform distortion to have a "sonic signature." Wire can have a subtle sonic signature, and in some cases a gross signature, but in general, with common and exotic wire alike, all measurements and all blind tests show exactly the same thing. Are they missing something? Not according to the understanding of most engineers. Audiophiles tend to disagree, based entirely on what they hear or think they hear. I guess one simply has to decide which is more reliable. I've made that decision based on years of experience and some hard lessons. Nobody can get involved in DBTs and not learn how unreliable their senses are without going into deep denial.

    Quote Originally Posted by pctower
    What do I think they overlooked? Possibly waveform distortion. That's why I asked the question. Why do you have to turn that question into something it is not. That's a Jon Risch trick, who would far rather discuss naysayers and yeasayers than technical issues..
    As far as i know I didn't turn your question into something it is not, and the personal attack is uncalled for. Why canít you participate without the personal attacks? What say we give it a try?

    What I said was that the author asserted that the parameters he measured told all there was to tell. That is a true statement, as can be verified by reading the article. I also said that if his assertion was true, then his measurements supported his conclusions. It is not a twist of your question to say that you were questioning his assumption, because you asked if his assertion was valid. You asked if he might have missed something, and his assertion was that he didn't. If you weren't questioning the validity of his assumption then what were you questioning? Didn't you ask if he might have caught something else (waveform distortion) if he'd run some additional measurements? Isn't that saying that his assumption that his measurements were sufficient is incorrect? That is all I said, and now you're in a huff about it for some reason that I cannot fathom. You know full well why he didn't look for waveform distortion in wire; It's so far below audibility that the JAES review board saw no need for such measurements, and neither do most other people. Jneutron and I both DO measure such things at times, or at lest we try, but most technical people have better sense.

    I don't mind answering your questions, to the best of my ability, but if you're going to get upset when I try, it's not going to be worth the effort. If you can't keep yourself under a little better control the only people who will want to talk to you are those who come here looking for argument.

  24. #24
    Forum Regular Chuck's Avatar
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    Quote Originally Posted by pctower
    Chuck - please stop putting words in my mouth.
    My take is that you are grossly over-reacting in a highly emotional and illogical way, and I have no interest in that type of discussion. As a result I've asked Chris (our moderator) to comment, and until I see some change I intend to try to improve your comfort level by adding you to my blocked-posters list. Perhaps you could do me the courtesy of doing the same?

    We can easily unblock at some time in the future if there is any reason to believe that we can have an enjoyable conversation without you getting upset over something that doesn't amount to a hill of beans. In the interest of peace and harmony on the forum let's both do Chris a favor and ignore each other.

    Thanks.

  25. #25
    Forum Regular Chuck's Avatar
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    Off topic, but possibly relevant to some, the "blocking" function of our forum is pretty cool. All you have to do is access a users profile and elect to have their messages blocked. Their names still show up when they post, but even if you accidentally click on one of their posts, the message text is not displayed. Gives one an easy way to avoid reading the drivel from people who they find offensive or undesirable and if used liberally it just might make this forum an even more enjoyable place to visit.

    Overall I like the new format and options.

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