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In Reply to: Re: You can’t compare the end result. posted by Soundmind on January 2, 2005 at 20:00:09:
Soundmind you are really an old dog that can’t learn to sit, and clearly under your sun there are nothing new…I gave you perfectly good examples of what could be causing the things we hear, but you didn’t really address any of them in your responses. Why? Is it because you know that you can’t argue against them? And put attention to that I said “could be causing” I have never proposed that what I am saying is the only truth like some others, but as long as I hear differences I have to seek answers.
“When TOTAL harmonic distortion is measured in tenths and hundreths of one percent, it doesn't matter how it is spread out. I believe that they are all inaudible.”
If you can’t hear it, then it’s good for you. BUT just because you can’t hear it you can’t sit there and say that it doesn’t matter. I have to trust my ears. I talked with my brother about this yesterday, and we compared this issue with the ability to hear the difference between different acoustical-guitar brands. I can hear the difference between a guitar with steel strings and one with nylon strings, and I can hear the difference between guitars of different size and shape. BUT I can’t hear the difference between different brands if they are of similar shape and size, but there are people who can do this and just because I can’t hear it I can’t say that it doesn’t matter…
“BTW, if you don't think errors in control systems are important, think again If an amplifier feedback system fails, the worst that can happen is it goes into spontaneous oscillation and blows up destroying a device which at most is worth a few thousand dollars and frankly its parts are worth only a few hundred. If an industrial controls system fails or the design is faulty, the damage to equipment and machinery can easily run into the millions …”
You know that I was referring to the error between the wanted output and the actual output in a control system, the error signal. But you respond by talking about money and system failure??? Money is NOT the issue here!!! If an audio amplifier goes into spontaneous oscillation it’s just a bad design and a competent electrical engineer would have corrected it for this, and if you have encountered control system failure because of faulty design from your part and lost a lot of money, bad for you.
(And I’m fully aware of that control systems can be unpredictable and cause problems, but that was not the issue here)“I think 70 to 75 db S/N ratio for vinyl is a little optimistic. I think realistically, at least for most of what was produced in the real world, 55/60 is more like it.”
What I said was that “vinyl works despite the S/N-ratio of around 70 - 75 dB at it’s best”. “at it’s best” means that this figure is not reached all the time. And there has been development in this area too in resent years resulting in much lower surface noise and hence better S/N-ratio. I have a couple of records with I think surpass 75 dB S/N-ratio, maybe I should make some measurements… Hmmm
BTW Vinyl is still produced and most of it surpasses those records produced in the 80’s regarding to technical specifications.“So at what threshold percentage as a function of f and N does each of these harmonic distortion components become audible?”
Soundmind you are again showing your incompetence and inability to grasp the whole picture by asking for a blunt number of distortion %. The answer is that it depends! I recommend you to read
“Just detectable distortion levels” by James Moir Wireless World Feb 1981
“Some Defects in Amplifier Performance Not Covered by Standard Specifications” by Norman Crowhurst. JAES Oct 1957
“Do your ears deceive you?” by Tom Farrimond. Practical Hi-Fi Jan 1980
“Inaudible High-Frequency Sounds Affect Brain Activity; Hypersonic Effect” by Oohashi et al. The American Physiological Society.
And the AES preprint # 3207 September 1991“Capturing Music: The Impossible Task” by James Boyk. Seminar at the University of California, San Diego April 2004
When you have read these papers you should be aware of that it depends on frequency, level, what you are listening to (i.e. how long, in time, are the high level peaks in the program material) and the order of harmonics among other things. So you just CAN’T just give a blunt number, but maybe it works in your simplified world.
The article by James Moir says most of it, so if only care to read one, read that one.
This far we haven’t talked about the interactions between the amplifier and the loudspeakers because of EMF, and then there are other even bigger cans of worms we haven’t touched yet. It’s interesting to se that with every step of “development” we end up with less linear devises, with DHT-tubes being the most linear device ever made. I know that tubes have their problems and limitations and that bjt’s with local feedback can have better measurements, but the listening impressions can tell another story…
Enjoy Creating / Mad Man Harju
Follow Ups:
“could be causing”Engineers and scientists don't work on "could", they work on IS. It's the same silly arguement as the cables. Proponents of certain equipment just like certain cables are long on theories and generalities and very short of facts and data. They would have you believe that the process of improvement is infinite, and that there is no point beyond which further electrical improvement doesn't offer any usable audible benefit. They claim they can hear what can't be measured. This is extremely self serving to those in the business of making and selling products because it opens the door to an infinite number of new and improved models which can never be tested to see if they actually are of usable value over the previous art. This is rediculous and it is not the way of science. Scientists establish the absolute criteria beyond which further improvement cannot be usable because of the limits of human perception and then they find a way to measure their designs against those criteria. Once they have bettered them, there is no need to go any further except to make their designs cheaper, smaller, more efficient or more reliable.
"BUT just because you can’t hear it you can’t sit there and say that it doesn’t matter."
Take my word for it, if you can hear it, it CAN be measured. OK, don't take my word for it. Next time you take a hearing test, ask your audiologist. And if you can't hear it, it really doesn't matter. In fact, many times reproducing what is inaudible creates new problems without offering any benefits. There would be no reason for a television set to be designed to reproduce infrared and ultraviolet colors. They also add nothing of benefit.
"Soundmind you are really an old dog that can’t learn to sit, and clearly under your sun there are nothing new…"
Under my sun, there are facts and there is hype. Hype is used when there are no facts to sell to uninformed or untrained people what more knowledgeable people will pass off with a laugh. At least in that regard, you're right, there is nothing new. And you are also right about the fact I don't just sit passively for a lot of it.
“Under my sun, there are facts and there is hype. Hype is used when there are no facts to sell to uninformed or untrained people “This is why I design and build my own amplifiers, pre-amplifiers and loudspeakers, because the hype causes the investment needed to by some of these up-hosed amplifiers climb to a ridiculous level. And I’m currently working on a idea of an record-player in the back of my head based on some ideas from J C Verdier, if I pull that of I can have a complete reproduction chain of my own design…
BTW I didn’t mean to attack you personally in any way Soundmind, but this time you just have to accept that you have to take the heat for all of your peers…
Enjoy Creating / Mad Man Harju
For Soundmind, 'is' appears to be delimited by what is accepted orthodoxy among certain of his peers.
Happy new year..hope yours is a good one..Tom: ""For Soundmind, 'is' appears to be delimited by what is accepted orthodoxy among certain of his peers. ""
I know that when I work on systems that are mission critical, or are needed for human safety, I will always use "known orthodoxy". To do otherwise is to invite disaster..my employer expects it, as I am sure yours as well as Sound's...So, his approach of "show me the proof, and I will learn", is certainly a valid one.. he just doesn't seem to want to blindly accept gratuitous handwaving..can't blame him, really..
I'm happy, though..that this thread, with one exception, has been a delightful one to read..I thank all..
This is, IMHO, how it should be..
Cheers, John
Happy New Year back atchoo!I agree - this is one of the more interesting threads overall. I feel that 'engineering' can encompass a wide range of approaches, depending on what the objectives and available resources are.
Statements like this:"When TOTAL harmonic distortion is measured in tenths and hundreths of one percent, it doesn't matter how it is spread out."
certainly suggest that Soundmind is pretty fixed in his worldview. He made a statement that is completely unsupportable. I'm sure the response to any objection will be to demand proof that higher-order harmonics are audible...sigh...
How about if HE did a little research into the work others have done over the last 20 years BEFORE making ten commandments-type pronouncements? Engineering has moved on....
Here's an intersting question: did anyone ever PROVE that THD meant anything? It seems to have developed a near-mythical importance as a measurement, but I don't recall seeing any evidence that all harmonics ARE equal..
BTW, thanks for the New Year email -- right back at ya! I was off in Death Valley for the week, so I missed most of this wonderful thread...
Peter
You ask questions I cannot answer..There are two things that are really bugging me at the moment...
1. What mad man harju said about 10 uSec lateralization delays being audible....somewhere, I've heard that before...of course, I've been saying 5 uSec.
2. The fact that Bill Haley and his comets are not a current band, with today's recording technology available..I made some CD's with fifties stuff for a n.y. eve party, and I can't stop singing shake, rattle, and roll.
From what I am seeing here, we are all saying pretty much the same thing, in different ways...I had this same argument with MTRY a while back, when I started skin effect measurements and wire inductance modelling solely based on the anecdotal accounts of others, with the desire to back into possible audibility...whereas he condsidered that a backwards approach..correct, he was, with respect to scientific methodology, but I consider the cows to be already out of the barn...so approach the problem from the opposite direction..looking for what is causing the anecdotal accounts..yes, one has to always consider the possibility that one is seeing what one desires, so my method requires closer self inspection and peer review...but it's fun.
Oh, JC....while I will acknowledge successes of designers such as yourself, I do not consider a list of publications one reads as an indicator of one's ability to understand those publications..I can drop the names of some, shall we say, "high end" physics guys I've worked with, but that doesn't necessarily mean I understand one iota of their work..
As for the power amps of today, when one views 5 uSec temporal accuracy at these impedances, all the amps that have been built today are inadequate...not a one has been designed correctly to that speed when pushing a reactive load in the 2 to 8 ohm region. And, not a one can test to those requirements, say 1 uSec for margin.....power load technology is entirely inadequate..and design layout is shabby.
Cheers, John
(see ya later, alligator...)
PS...tis a wonderful thread, isn't it!!!!
"As for the power amps of today, when one views 5 uSec temporal accuracy at these impedances, all the amps that have been built today are inadequate.."Hahahahahahahahahahahahahahahahahahahaha
My reference sound system in some modes has 4,500,000 microsecond delays and more.
Happy new year John.
"1. What mad man harju said about 10 uSec lateralization delays being audible....somewhere, I've heard that before...of course, I've been saying 5 uSec."I didn't know that ;-)
Enjoy Creating / Mad Man Harju
1. What mad man harju said about 10 uSec lateralization delays being audible....somewhere, I've heard that before...of course, I've been saying 5 uSec."MMH: ""I didn't know that ;-)""
Perhaps you should get out more??? :-)
Nordmark provided 5 uSec lateralization capability without jitter, in the 500 to about 1.2 Khz regime...and down to 1.5 uSec in the 2Khz to 12Khz regime when one includes jitter in the 6 uSec arena.
I note that a 6 uSec jitter is well within the capability of most dynamic drivers simply as a result of excursion at low SPL's. So, there is a reasonable mechanism already there, to provide for the enhancement of lateralization up to 12Khz..
When's the last time anyone measured an amp for power/timing accuracy at a Meg (1 over 1 uSec), with a reactive load??
Cheers, John
Engineering is NOT a haphazard process. It starts with a specified set of design criteria. These criteria are established for a reason. In the case of a state of the art high fidelity audio amplifier, the criteria may include power output, bandwidth, harmonic distortion, intermodulation distortion, noise, frequency and phase response. The levels and types of distortion must be established by knowing what levels are audible and what aren't. If they vary by frequency or by the percentage of particular harmonics present in the output which are not present in the input, that must be known too. If the levels of distortion needed to be inaudible are unknown, the engineer approaches a scientist who makes a study to determine what they are. If the methods of measurements accepted by industry are deemed unsatisfactory or inadequate, the engineer approaches scientists as well who study where they fall short and devise improved methods to yield a more accurate or truer useful picture. All of these scientific studies need to be published in professional journals documenting every step and conclusion so that they can be judged independently by professional peers, not in consumer magazines where they are bandied about by amateur hobbyists. Certainly not in publications like Stereophile magazine. And not on internet web sites owned by the proponent. Until that is done, all of the talk is just a bunch of unproven theories. Then when the design criteria and the methods used to test the results are established, the engineer goes to work designing, building, and testing the circuit to determine whether or not it meets the initially specified criteria. That is not orthodoxy, that is engineering. Not just electrical engineering but ALL engineering. Anything less, even by well thought of, well reputed, and financially successful people is just tinkering and they are not engineers, they are dilletentes. It is easy for these people to make claims that neither they nor anyone else can substantiate. However, while they might be taken seriously by neophyte consumers and hobbyists, they will not garner acknowledgement by other engineers until they have successfully passed the rigorous criteria I have outlined.
then what?
was engineered in the same way.NOT !
The final voicing of any instrument or device designed to faithfully produce or reproduce music requires a test instrument having two ears.
rw
I recall seeing a television program about Steinway. As I recall, the method he used to make the world's greatest piano and the brand most widely used by performing and recording artists even today was to hire people from all of his competitors and steal their best ideas. Now I think that's pretty clever. This was in the days before anyone ever heard the term "industrial espionage."
I have been a professional design engineer for 37 years, and have been a member of the IEEE for 40 years.
Soundmind, are you a member of the IEEE? If so, what journals do you read monthly? I subscribe to:
'Proceedings of the IEEE'
'Circuits and Systems'
'Solid State Circuits'
'Instrumentation and Measurement'
'Consumer Circuits'
'IEEE Spectrum'
I have been a member of the AES for an equal length of time, and read the Journal every month. I also read 'EDN','Electronics Design','NASA Tech Briefs', 'The Industrial Physicist', 'EE', 'Sensors', and a number of other smaller technical magazines.Who are you to say how an engineer should design?
It just so happens than audio design needs another feedback mechanism rather than one in a circuit or implied by a mathematical calculation. It needs: THE HUMAN EAR.
Without this feedback mechanism, it is you who is tinkering about blindly, wasting time, effort and money. Both Rolf and I have the education and experience to know this. This is the difference between a successful audio designer and a time waster.
I have nothing against your process, I which things could work this way…“If the levels of distortion needed to be inaudible are unknown, the engineer approaches a scientist who makes a study to determine what they are. “
Why couldn’t the engineer do that, or don’t you trust your own ability to do that. And who would pay for this since most of those who have the means to do this kind of study in the audio industry are in it to earn money.
“All of these scientific studies need to be published in professional journals documenting every step and conclusion so that they can be judged independently by professional peers, not in consumer magazines where they are bandied about by amateur hobbyists…. Until that is done, all of the talk is just a bunch of unproven theories…. Anything less, even by well thought of, well reputed, and financially successful people is just tinkering and they are not engineers, they are dilletentes”
Exactly how many papers have you published in this way?
Regarding audio amplifier design?
If none then you too are a dilettante…
Or someone who just repeats what he has read or heard without thinking for him self.
Enjoy Creating / Mad Man Harju
> Why couldn’t the engineer do thatHe would risk playing 'scientist' without the right degree.
"“If the levels of distortion needed to be inaudible are unknown, the engineer approaches a scientist who makes a study to determine what they are. “Why couldn’t the engineer do that"
He can. But when he does, he has taken off his engineering hat and put on his scientist hat. It's a different function, basic research compared to applied science (engineering.) Engineers are not precluded from performing scientific work as well. Some are even good at it.
"Exactly how many papers have you published in this way?
Regarding audio amplifier design?
If none then you too are a dilettante…"Absolutely....none. Am I a dilettante? No, I'm not even that. In audio I'm just a hobbyist (although I do have a US patent but that's a different story and I'm not getting into it here and now.) However, while I may not be an expert or even an experienced amateur in amplifier circuit design (it's been 35 years since I studied it in college) I am highly experienced with the methods and processes engineers and scientists use and that cuts across all disciplines. BTW, the current terminology for proving that the performance of complex engineering systems meet their stipulated design criteria is called "validation." When you see an ad for a validation engineer or meet someone who is a validation engineer, it's his job to put engineering equipment and systems through its paces to prove that it meets its specified design objectives. And this too cuts across many disciplines and industries such as pharmaceutical, nuclear power, manufacturing, and power generation and is required by government regulatory agencies. Just proving that a specific piece of equipment meets its specifications (design goal) is called acceptance testing and documentation is called certification. This is nothing new, at least not under this sun.
"Or someone who just repeats what he has read or heard without thinking for him self."
You read it over and over again in the required processes from those specified by NRC to ISO and ANSI among many more. To put it succinctly in the words of an ISO 9000 compliance officer of one company I worked in, "say what you mean, mean what you say, and have the (tests and) documentation to prove it. And when I think about it, it makes perfect sense to me.
“To put it succinctly in the words of an ISO 9000 compliance officer of one company I worked in, "say what you mean, mean what you say, and have the (tests and) documentation to prove it.“Yes I know to well about it, when I worked at one of the Swedish Army’s repair shops earlier in my life I was working with certifying the whole business against ISO 9000…
This thread has got little of topic now and clearly lost some steam. So we might just have to start up a new one on some other interesting topic… This is how it should be, you have interesting and intriguing discussions and might in the process lean something. Thanks for me!
Enjoy Creating / Mad Man Harju
I have been a professional design engineer for 37 years, and have been a member of the IEEE for 40 years.
Soundmind, are you a member of the IEEE? If so, what journals do you read monthly? I subscribe to:
'Proceedings of the IEEE'
'Circuits and Systems'
'Solid State Circuits'
'Instrumentation and Measurement'
'Consumer Circuits'
'IEEE Spectrum'
I have been a member of the AES for an equal length of time, and read the Journal every month. I also read 'EDN','Electronics Design','NASA Tech Briefs', 'The Industrial Physicist', 'EE', 'Sensors', and a number of other smaller technical magazines.Who are you to say how an engineer should design?
It just so happens than audio design needs another feedback mechanism rather than one in a circuit or implied by a mathematical calculation. It needs: THE HUMAN EAR.
Without this feedback mechanism, it is you who is tinkering about blindly, wasting time, effort and money. Both Rolf and I have the education and experience to know this. This is the difference between a successful audio designer and a time waster.
“Both Rolf and I have the education and experience to know this.”This is dangerous territory John, I don’t consider myself that experienced that I can compare myself, my knowledge and my designs with the likes of you… YET
There might come a day to that, but I have a lot of learning to do until that.
Enjoy Creating / Mad Man Harju
Rolf, you are on the right track. IF you can get a technical education and THEN realize that there is more to audio design than just numbers on a computer or from a piece of test equipment, then you can make real progress. The problem with many with audio, is that some become technically educated, but remove themselves from discerning audio differences, and think that it is all hype. Or else, they never get a technical education and just constantly tinker with circuits and loudspeakers, never really refining any general principles, but they still may achieve some success with what they put together. It just can't be duplicated by anyone else, in general.
The trick is to be open minded to what works in audio, but having the technical background to ultimately make sense of what you hear, and perhaps derive a test procedure, or a design approach that is more successful than the typical mid fi design approach.
Hi JohnI have a technical education and have been upgrading it the latest four years and am supposed to write my thesis so I can get my degree in electrical engineering AGAIN but at a higher level. And I realize that there is more to audio design than just numbers on a computer or from a piece of test equipment. So I might have big chance to get the grasp of audio related things in amplifier design.
“The trick is to be open minded to what works in audio, but having the technical background to ultimately make sense of what you hear, and perhaps derive a test procedure, or a design approach that is more successful than the typical mid fi design approach.”
I think you are right on the spot here.
Enjoy Creating / Mad Man Harju
In the past I have been a member of IEEE, AES, ASA, and AIP. I've read their journals but no longer have any time for them or my memberships which have lapsed. This does not address the points I raised.
I need to keep up with what is happening in engineering. Are you telling me that you don't need technical journals to keep up-to-date?
I just don't have the time anymore. I certainly wish I had. Unfortunately my work, my current interests, and my other responsibilities do not allow me the luxury of the time to pursue them anymore.
That's OK, Soundmind, I understand.
For me, subscribing to journals is necessary to keep current and to subject me to heavy math and concepts so that I don't forget what I learned in university, 40 years ago. ;-)
With the normal analog engineering that I do, heavy math is not important on an everyday basis, and what you don't use, you lose. You are obviously working on stuff that keeps you sharp. Nothing wrong with that.
My point is that I am not just some sort of tinkerer with circuits. I take engineering seriously, just like you do.
Unfortunately, I have had designs fail to sound good, without initially having any reason for it. I have learned to trust in 'what works' and at the same time I try to design circuits that measure well.
It is very easy to fool yourself and come to the wrong conclusion about why something seems to work well or poorly. This is why we have this rigorous science. It's not to put down anyone who wants to be innovative or to invent something that is better, even much better. But when you want other people at your level to respect what you have to offer, they need to be convinced that you know why or if you are guessing, even if it's an educated guess, you are not precluding the possibility that there isn't something we're missing.Engineers and scientists make mistakes just like everyone else. That's why we need other people to check what we do to be certain we haven't overlooked something. The more critical the project, the more important the second opinion. In the nuclear power industry, it's called "independent design review" and the engineers who check out a project in this function have no connection with the project itself. If you're in my boat, you never know if you haven't made some horrible mistake until they throw the switch. When the smoke clears, suddenly everyone's an expert. (thank god that hasn't happened to me...yet.) If I don't take home audio equipment too terribly seriously, maybe it's because the consequences of being wrong don't seem that catastrophic to me.
In my world, it is called independent listening feedback.
“Engineers and scientists don't work on "could", they work on IS.”
“…what more knowledgeable people will pass off with a laugh.”Did you also laugh when Otala and later Walt Jung presented their theories of TIM and SID, because before that it was never heard of, among your kind of people, that amplifier stress at high frequencies could cause audible effects. Today this is accepted and a part of every good engineers “checklist”.
“Scientists establish the absolute criteria beyond which further improvement cannot be usable because of the limits of human perception…”
Is the limit of human perception really reached yet? Take as an example our ability to distinguish changes in the direction to a sound-source of less than ONE degree in the frequency-range around 2 kHz. This corresponds to a time difference between the ears of 10 us or a frequency of 100 kHz. This would imply that the phase and frequency response of a system is important beyond 100 kHz.
“Take my word for it, if you can hear it, it CAN be measured.”
Nobody knew how to measure the effects of SID before Walt Jung showed how to do.
And what I am pointing at is just the fact that I can (and many others with me) hear differences but our current measurement methods don’t reveal this. That is why we are looking at different measurement methods to se if they correlate with what we hear, and since this is yet to be proven we must say “could be causing”.BTW People “who work on IS” ONLY will never be the ones who bring the progress into new territory.
And about the really big can of worms with cables that you brought up, my take is like this; I think that much of it is exaggerated but that there are very small differences, which may depend of a number of reasons. A cable is also a capacitor connected in parallel with the load, and the capacitance isn’t that linear regarding to frequency and amplitude. Well not even good capacitors are that so why would a cable be that. (And maybe, just maybe, skin-effect can be a small part of what might cause the capacitance to change and hence causing phase modulation and that is perceived as “time smear”). And we all know that a frequency response that is modulated by signal-amplitude cause signal dependent phase modulation. And then we have the issue of the inductance of the cable witch also can be non-linear regarding to frequency and amplitude.
And a part of the “problem” may in some cases be just an interaction issue, the pre-amp or amplifier with or without a feedback loop might not work well with that particular load.
And when we are talking of loads, why do people of your kind Soundmind persist on making measurements of power-amplifiers with a purely resistive load? The answer I usually get is that every loudspeaker is different and there is no point to try to make measurements with a load that resemble an average load. This is to be blunt JUST PLAIN WRONG.
Loudspeakers (and I mean all loudspeakers) store quite significant amounts of resonant energy, and for relatively long periods of time (tens to hundreds of milliseconds) and this back-EMF interacts with the non-linear amplifier and creates new distortion terms. Just ask any skilled loudspeaker designer. And amplifiers connected to these real loads will not behave as nicely as measured with a purely resistive load If we use LCR networks that simulate the overall impedance of the speaker in our measurements we get a bit closer to the real thing, but to get all the way we need to measure with real loudspeakers and preferably with several different loudspeakers.
And again Soundmind you haven’t addressed my examples of what could be causing the things we hear. You are just so hell-bent on insisting that “if you can hear it, it CAN be measured”. It doesn’t matter how much we tell you that we hear differences that don’t relate to the measurements. And as long as we hear differences we have to seek answers.
And yes I’m also very suspicious when somebody comes with a “new” explanation to some of the things I’m hearing. But I almost get MAD when somebody is trying to tell me that I can’t be hearing what I’m hearing because we can’t measure it.
BTW Last time I checked my hearing, my threshold of hearing was almost 10 dB lover than the normal hearing limit in the range of 1000 to 3000 Hz. But I don’t hear as good as I used to in the high frequency range with my hearing starting to fall of above 15 kHz, due to age and exposure to loud sounds. But my hearing did fall of above 18 kHz already at an age of 15 so I haven’t lost so much or the years…
Enjoy Creating / Mad Man Harju
"And when we are talking of loads, why do people of your kind Soundmind persist on making measurements of power-amplifiers with a purely resistive load?"I agree. On this one you are preaching to the choir. The methods for measuring and specifying amplifier performance do NOT correspond to the way they are used in the real world. If you have read my postings on the subject, you will see that I have said that much more work needs to be done to bring those measurements into conformity with their normal application. And I agree that not only are loudspeaker loads not ordinarily purely resistive, they are not even passive loads. That explains at least in part why different amplifiers measuring the same by our antiquated methods sound different. This however does not excuse the maker or marketer of amplifiers to make claims he cannot substantiate. What it does is to prod him to hire or become the scientist who develops new objective criteria and present them to his peers so that they will accept his claims. It is not good enough for Otala to theorize about TIM, he had to define it, devise a way to measure it, and show that his designs were a valid improvement in reducing it. I am not opposed to progress. But mere claims are not progress. That is why we have a scientific method and peer groups who challenge and duplicate test results. When they are proven, they become part of the science and are legitimate fodder for the ad men, not before.
“Take my word for it, if you can hear it, it CAN be measured.”
I'll stick with that. We have sound transducers much more sensitive than the human ear drum and we have the electronics and mathematics to analyze anything fed into or coming out of them. Once again, if it isn't being done yet, that does not give anyone license to make claims based on the unproven and expect to be taken seriously by other engineers. You do the science, publish it for all to see, and when the majority of us are convinced, we accept it as the new expanded version of the science.
"And yes I’m also very suspicious when somebody comes with a “new” explanation to some of the things I’m hearing. But I almost get MAD when somebody is trying to tell me that I can’t be hearing what I’m hearing because we can’t measure it."
I am not necessarily suspicious about someone coming up with a new insight into sensory perception or how our brain interprets it. But because our senses are so easily tricked, especially our hearing and because our memory of sensory perception is so fallable, here more than ever, carefully devised and performed experiments must be conducted to determine what people actually can and can't hear. And again, the criteria of proof is the ability of other skilled scientists and engineers to look at claims, data, methods, results, and try to repeat them or shoot holes in the logic which connects them. Then when a difference you think you hear is proven to exist, it becomes incumbent upon people studying it to correlate the difference with objective differences in electrical and mechanical performance to explain how and why those differences come about, not to advance unsupported theories as proof. That is what science is all about and that is what is usually lacking in the consumer audio industry insofar as "high end" products as well.
“But mere claims are not progress”The papers and articles I recommended you to read are not mere claims.
Check them out."Multitone Testing of Sound System Components-Some Results and Conclusions"
JAES Vol 49 No 11 2001 November.“Just detectable distortion levels” by James Moir Wireless World Feb 1981
“Some Defects in Amplifier Performance Not Covered by Standard Specifications” by Norman Crowhurst. JAES Oct 1957
“Do your ears deceive you?” by Tom Farrimond. Practical Hi-Fi Jan 1980
“Inaudible High-Frequency Sounds Affect Brain Activity; Hypersonic Effect” by Oohashi et al.
The American Physiological Society.
And the AES preprint # 3207 September 1991“Capturing Music: The Impossible Task” by James Boyk. Seminar at the University of California, San Diego April 2004
There are more but this have to do for now.
Enjoy Creating / Mad Man Harju
""“Inaudible High-Frequency Sounds Affect Brain Activity; Hypersonic Effect” by Oohashi et al.
The American Physiological Society.
And the AES preprint # 3207 September 1991""As best as I recall, there were some significant methodology errors in that paper, but cannot for the life of me remember what they were..do you recall the problems?
John
“Inaudible High-Frequency Sounds Affect Brain Activity; Hypersonic Effect” by Oohashi et al.There are three different versions of this paper first the preprint to The American Physiological Society Convention and then the AES preprint and lastly the version from the Journal of The American Physiological Society. The first two are little sloppy but the third (witch I found on The American Physiological Society’s homepage if I remember correct) are pretty Ok. But it was a while since I’ve read it and I can’t recall any problems now at the moment, I have to read it again…
This is not the paper where they used a tweeter witch couldn’t handle the high-frequency information and distorted because of that. And I only included it to show that there may be measurable differences in our brain activity du to high-frequency effects.
Enjoy Creating / Mad Man Harju
MMH: ""And I only included it to show that there may be measurable differences in our brain activity du to high-frequency effects. ""
I personally can prove with 100% accuracy that this is so, and that is based entirely on experience on the production floor.I'm also confident that the ultrasonic welder guys, like "sonics and materials", located in Conn., can relate the same thing. I am starting work on some 40Khz tansducers, 700 watt thingy's, so I will be able to relate experience with that freq soon enough.
What I was not happy about, was the OSHA criteria for workplace limits of exposure at these frequencies. They spec'd limits based on one of the weightings (I forgot which one), and the meter was incapable of measuring the U/S energy that affected my hearing. So, we used ear protection in the app...clearly, OSHA had not really covered long term U/S exposure vs hearing damage, we didn't want to take a chance.
Cheers, John
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