OK, so if something is wrong, no-one should say anything. Unless, of course, it's someone YOU disagree with (like Lipshitz's work or the guys who published the ABX stuff), then it's fine.
Riiiiiiight.
Well, I kind of see the point. There was some clown, who "quoted an article" saying that a Nelson Pass design was rated poorly. Then N. Pass had to set the record straight. The clown later tried to weasel out of it by claiming a "poor memory".
Folks should not have to defend themselves from the thoughtless.
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I'm glad you've taken up the challenge to defend Cheevers. Let's not forget that this is not merely a paper which was published in a technical journal, this thesis was the difference between him being seen by the profession as a bachelor of electrical engineering and a master of electrical engineering so it is much more important.
So in addition to my criticism above where he failed to establish that there is a threshold below which distortion is not audible no matter what its distribution in terms of which harmonics (or non harmonically related signal) is present, how do you defend the fact that he did not have a control element in his examination, that is a way to test his thesis controlling only one variable, the spectral arrangement of the harmonic distortion products. In fact every amplifier he tested or cited had many differences in topologies, devices, and power supplies from the others. Not only that but the citations do not describe how the conclusions were reached, ie, what speakers,what source signal, what listening conditions. When you want to test a hypothesis, you have to devise an experiment where only the variable you are testing changes. He didn't.
Worst of all, as I pointed out, this is not a thesis about electrical engineering but about psychology, perhaps clinical psychology which examines the mind's response to physical stimulii and to related market research. It wasn't even a satisfactory thesis in that arena. Bad methodology, not science, and an effort to justify a conclusion he reached BEFORE any experiments were performed. And no followup trials whatsoever to prove that even his claims about preference were related to the variable he claimed to be evaluating.
I know you don't like getting down to critical examination of assertions or what supposed evidence there is to support them. That's not good marketing in an industry based more on a quasi religious dogma and testimonials than on hard science but that's the way real engineers and scientists think. That's how they obtain knowledge they can rely on whether it garners them opportunities for new products and profits or not. Now what is your counter argument to demonstrate that Cheever's thesis isn't junk science and that I shouldn't put EEs from University the New Hampshire on my same no hire list that engineers from Leeds University are also on?
No one stops anyone from posting here. If the authors wish to, they can.
I apologize for never presenting data and analysis. Maybe one day, I can figure out how to turn on this oscilloscope.
Is that your best argument JC? What have I done? If you can't attack the message attack the messenger? If you can't attack the messenger attack his credentials? Aren't you going to demand to know what my degrees and other credentials are? So what is your defense of a paper you lauded in the past or do you now admit it was defective and that you made a mistake? One thing I did not do is obtain a masters degree in electrical engineering based on writing a thesis I think is badly flawed and doesn't even relate directly to an electrical issue.
I lament the lack of critical thinking but I'm hardly surprised by it. I am not one who respects efforts, I save my endorsements for demonstrated results. A lack of them may in part explain why the market is now small and shrinking.
Soundminded: How can you make these statements. You were the guy that misqoutes an article and states that it criticized the Threshold amplifier. Then when you are caught on it by the designer in question, you try a weasel out of it by saying it was due to faulty memory.
Now we are supposed to take your "endorsements" seriously. IMO, you have little credibility at this point. Get your facts straight before you post your "critical thinking"
WT, does this mean you are going to take up the cause of defending Cheever? I knew sooner or later someone would. Frankly I was disappointed JC didn't. He seems to have forgotten and then disowned his lauding of that paper just five years ago. He said of it;
"Cheever's thesis is pretty good. It should be standard reading for audio designers."
Well that sounds like an unqualified endorsement to me. And to those who disagreed with him and just about anyone else within earshot he said;
"What is wrong with you people? Pay me, and I will try to do what you want! Mostly, you are a bunch of low rent jerks."
I really enjoyed that one. I can't say it's my favorite though, there were so many others to choose from.
BTW those were from the links I posted on #11844
"Cheever's thesis is pretty good. It should be standard reading for audio designers."
Well that sounds like an unqualified endorsement to me. And to those who disagreed with him and just about anyone else within earshot he said;
"What is wrong with you people? Pay me, and I will try to do what you want! Mostly, you are a bunch of low rent jerks."
I really enjoyed that one. I can't say it's my favorite though, there were so many others to choose from.
BTW those were from the links I posted on #11844
Soundminded: My comments do not imply an agreement or disagreement with the paper. I am simply pointing out that you made various statements that the paper said certain things (among them that the Threshold amp was poorly ranked). When it was pointed out that the paper said no such thing, then you claimed a poor memory of the paper. In fact, the Threshold was not even evaluated. Well, if you have a poor memory, then perhaps you should not make any statements without checking the facts first.
So your history is not a good one. You attribute things erronenously, you imply negative results to designs that were not even evaluated. Then you try and weasel out of it by claiming a poor memory. When someone then points out your "record" , you respond by saying that I must believe this or that. I don't believe this or that. What I believe is that your claims are not necessarily credible. Why I believe this is fairly evident.
So your history is not a good one. You attribute things erronenously, you imply negative results to designs that were not even evaluated. Then you try and weasel out of it by claiming a poor memory. When someone then points out your "record" , you respond by saying that I must believe this or that. I don't believe this or that. What I believe is that your claims are not necessarily credible. Why I believe this is fairly evident.
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Nah, he's just pointing out that you are quite talented at speaking out of both sides of your mouth in order to support your "argument".
WT, if you think I can remember all of the different amplifier brands on the market or who said what about which, you are mistaken. That is why I said right up front that I hadn't read the paper in five years and invited corrections. That is why when Nelson Pass pointed it out, I re-read it and found that he was correct and said so. The whole thing about people listening to equipment at someone's house and making judgments not in accord with published specifications or measurements had nothing to do with that paper. Now that I think back about it, it was at the beginning of Dr. Bose's white paper about his 901 speaker. Anyone want to point out the mistakes in that paper or is it too old to bother with?
Anyway, I stick with the gist of what I said, the thesis of Cheever's paper is bunk. I don't hear anyone disagreeing. BTW, Carver said he could make any amplifier sound like any other amplifier. If non linear distortion was audible, he couldn't do that. He says he does it by matching "transfer functions." But what is the transfer function of an amplifier. When you take away non linear distortion and noise it is....frequency response. That is where most or all of the differences can be found in the sound of systems when one amplifier is substituted for another.
Anyway, I stick with the gist of what I said, the thesis of Cheever's paper is bunk. I don't hear anyone disagreeing. BTW, Carver said he could make any amplifier sound like any other amplifier. If non linear distortion was audible, he couldn't do that. He says he does it by matching "transfer functions." But what is the transfer function of an amplifier. When you take away non linear distortion and noise it is....frequency response. That is where most or all of the differences can be found in the sound of systems when one amplifier is substituted for another.
Enough already with Cheever's thesis. It's beyond me why anybody would choose to waste 5 years of their life arguing about one single paper, that they don't even consider to be well written.
Think of all the time that COULD have been spent reading other papers. GOOD papers. That would also make for more interesting discussion here. Can we move on to something else now, pleeeease?
Think of all the time that COULD have been spent reading other papers. GOOD papers. That would also make for more interesting discussion here. Can we move on to something else now, pleeeease?
Soundminded, I do not know why you decided to mention the Cheever thesis.
Anyway, I strongly recommend to you to make your own test on audibility of harmonic distortion components. You will certainly find different threshold of audibility of 2nd and 7th harmonics
Because of your posting 11826. This posting was right in line with Cheever's assertion. I point out that the first harmonic component in the oscillophotograph is -80 db which is one part in ten million. The second harmonic component is nearly -100 db or one part in a billion. The total THD is clearly less than one part in a million. But even if you believe JA's assertion that he can hear increments of 1/10 db, that's 2 parts in a hundred. THD of most solid state amplifiers using negative feedback don't come remotely close to that threshold. About the only difference I can find between them is that with actual loudspeaker loads and within their power capabilities there are some differences in FR which are correctable with equalization. This would explain why one amplifier can be made to sound like another if Carver's assertion is true.
As for testing whether Cheever's hypothesis is right or wrong, I can't because I have not devised a circuit which could simulate the same total THD with different distributions of harmonic components. However, I'm sure some clever computer programmer could devise just such set of signals for DBTs. But then critics would challenge that because they say that they suffer some other shortcoming like digital jitter or whatnot.
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