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Cable Test Method

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Posted on November 17, 2002 at 12:42:30
JOEY.
Audiophile

Posts: 90
Joined: August 11, 2002
Hello All,

Differences in peoples opinions about they way a cable sounds (or doesn't) has always made me want to try to develop a reproducible test method to quantify any differences in cables.

I belive I have a setup that can measure cable differences down to about -100 dB (into the tens of microvolts anyway-see below) and I would like to sound out your views on the technique and develop it further if possible.

I would like to drive an interconnect with a 'suitable' signal form a 'suitable' source and measure the differences between input and output of the cable whilst connected to a 'suitable' load, using the differential amplifier plug-in (Tektronix 7A22) of my oscilloscope (Tektronix 7834). The TEK 7a22 amplifier has a bandwidth of 1 MHz and at its most sensitive is able to measure a differential signal down to a gain of 10 microvolts per division, with some residual noise (16uV or 0.1 divisions on screen), whilst differentially rejecting the signal in the output down to below 100 dB. (It has a common mode rejection of over 100 dB in the 10Hz to 100KHz range when DC coupled.)

OK then, say I use a one volt p-p signal, then this signal would be removed from the output by the amplifier down to a level of atleast 10uV, which coupled with the residiual noise means that 26 uV (10+16) would be the lowest measurable difference. The noise part of this figure can be improved on considerably by reducing the bandwidth of the amplifier (choices are 1MHz, 300kHz, 100kHz, 30kHz, 10kHz, 3kHz, 1kHz). As an example at 100Khz, (my preferred choice), the 16uV noise can be reduced to about 4uV, making 14uV the lowest measurable difference, not attributable to the equipment.

To get real world results I have always wanted to connect the cable to a real world source (say a CD player) and drive a real world load (a preamp or amp) and thereby cause the cable to be subject to real world component and source impedances. BUT, this does not make for a test method which is easily reproducible by others. So then I am faced with selection of a test source, say a signal generator, appropriate signal, appropriate artificial load etc..

My thoughts so far have been to try a triangular wave (as suggested in a similar Cardas test method), or a square wave or pulse signal and use a load impedance which simulates a 100kOhm source (some resistor/inductor/capacitor combination). Any further thoughts or comments, particularly regarding an appropriate load, source and test signal?

Thanks in advance,

HAVE FUN,

JOEY.

 

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Re: Cable Test Method, posted on November 18, 2002 at 14:45:10
john curl
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Posts: 4708
Joined: May 16, 2000
Joey, the action is at about -110db below 50 mV. I am measuring it at this level for the last week. Radio Shack is one of the worst, but many expensive cables are bad also, compared to JPS or Van den Hul , both of which seem to be virtually perfect in terms of higher order harmonic distortion. This is but one part of what is different in cables. Time response is another separate measurement.

 

Re: Cable Test Method, posted on November 18, 2002 at 15:27:29
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""Joey, the action is at about -110db below 50 mV. I am measuring it at this level for the last week. Radio Shack is one of the worst, but many expensive cables are bad also, compared to JPS or Van den Hul , both of which seem to be virtually perfect in terms of higher order harmonic distortion. This is but one part of what is different in cables. Time response is another separate measurement. ""

Is it possible that time response is the key issue? I wonder if 110dB below 50mV is in any way audible.

TTFN, John

 

Re: Cable Test Method, posted on November 18, 2002 at 16:45:29
JOEY.
Audiophile

Posts: 90
Joined: August 11, 2002
Hello John,

That's amazing: 110dB below 50mV (about 160 nV)!! It is amazing to think that such a difference could make a difference to the perceived sound! I suppose you are you using a spectrum analyser for such a low level signal. Can you tell me more about the test method and signal you used or suggest.

I will understand fully if you cannot respond for commercial-in-confidence reasons. Thanks in advance.

HAVE FUN,

JOEY.

 

Re: Cable Test Method, posted on November 18, 2002 at 18:12:56
eico1
Audiophile

Posts: 62
Location: nocal
Joined: November 12, 2002
my receipe is get a pre-amp with a l-r setting, insert cable 'a' into one channel and cable 'b' into the other, play your favorite cd and crank the volume.

steve

 

Re: Cable Test Method, posted on November 18, 2002 at 18:30:00
john curl
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Joined: May 16, 2000
John Es, you ask me to be polite, yet you 'snipe' at my efforts, just like you did with Dr. Hawksford. I KNOW what I am measuring, and every cable type has a different spectrum. I am learning something here, and you are not teaching me anything.
Please! Read a tech. book, ask your associates down the hall about things, or ACTUALLY measure something yourself. Chipping at my efforts does nothing. Your 'opinion' is no better than that of any layperson.

 

Re: Cable Test Method, posted on November 18, 2002 at 21:04:56
JOEY.
Audiophile

Posts: 90
Joined: August 11, 2002
Hello Steve,

That is a good method, but you would need to use a mono signal into both channels to be fair and you would of course have to listen, (not that I am adverse to music) ,but this opens the possibility for observer bias and will have others requiring that we use DBT techniques when the test results are presented for scientific review/publication. Your switching method is certainly a good way of getting around the problem of short auditory memory, without introducing extra circuitry. Thanks.

HAVE FUN,

JOEY.

 

Re: Cable Test Method, posted on November 18, 2002 at 21:10:15
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Joey, I hope that you now understand that it is difficult, but NOT impossible to measure differences in non-linear distortion in interconnect cables. Normally, I use harmonic distortion, because it is relatively straight forward, and with a pre-nulling of the fundamental, I can see at least 125dB down. Years ago, Dr. Van den Hul found that there appeared to be a 'dead zone' at low levels in many wires. He talks about it on his website. He measured it years ago with test equipment that he got surplus from Phillips Research Labs. He also lives in the countryside, so RFI is not as big a problem as many of us have. He told me about his measurements about 15 years ago. In 1991, I finally got a wave analyser that could 'just' measure differences between different interconnect cables, and friends and associates donated cables for me to test. Because of the low working signal level, I have always been plagued with noise and RFI artifacts. Still, I could see measured differences. Later, I used a spectrum analyser program with my MAC computer to analyze the distortion output of my Sound Tech 1700B THD-IM analyser. It worked, but it still took time and trouble. Also, the cynics on this website picked and poked at my results, as they tend to do, and I finally decided to get an HP 3563 analyzer, to make the measurement easier and fast. Now, I can easily measure any wire for low level distortion.
Now, my measurements are fairly low down, BUT I am using only ONE tone, and not a whole lot of frequencies to make the test practical. It can be shown that IM distortion can be at a significantly higher level. So, just now, I did an SMPTE IM distortion test and the distortion levels are, in fact, even higher! Then I tried a 10:1 hf/lf ratio rather than 4:1 and got even MORE distortion. The distortion that I am concerned with is HIGHER ORDER, not 2n'd or 3'rd, because these low order distortions are benign and always present in loudspeakers, etc.
Initially I gave you an estimate of what it takes to measure nonlinear distortion in a connecting wire. There are other distortions as well, of course. For example, there is 'linear' distortion that will only significantly appear with asymmetrical test tones, which is normally defined as DA. And of course, there are many time smearing factors, such as 'skin effect' etc that will change the time response of a wire. That is another measurement entirely, and could be equally or more important than what I am measuring. I wish you luck in your testing.

 

Re: Cable Test Method, posted on November 18, 2002 at 22:27:05
JOEY.
Audiophile

Posts: 90
Joined: August 11, 2002
Hello John,

Thankyuou for taking the time to put toghether such a detailed response. One last question if I may: In your other post you mentioned that the differences "action" was 110dB below 50mV. By this did you mean that you were using a 50 mV test signal amplitude? I can certainly understand this as being a representative real-life average voltage in the cable, but I wonder about pushing it higher to 500mV or 1 V for better S/N in the test. Any thoughts? (sorry, that was 2 questions) Thanks in advance.

HAVE FUN,

JOEY.

 

Re: Cable Test Method, posted on November 19, 2002 at 01:10:46
kuribo
Audiophile

Posts: 1759
Location: sw wi
Joined: June 27, 2000
JE asked a very legitimate question-a question that is of the utmost importance, actually. Why don't you answer it, if you can, instead of whinning like a little kid?

Seems to me that you yourself would want to know the answer before you spend all your time and money pursuing something that could, realistically, be of no audible consequence.

Are you measuring the gravitational effects of the full moon on these cables?

 

I'M SORRY I ASKED.........., posted on November 19, 2002 at 03:44:55
JOEY.
Audiophile

Posts: 90
Joined: August 11, 2002
Hello ALL,

In the interests of free and open discussion I feel it is imperative that we all maintain a friendly attitude. Of course it is possible to challenge an opinion or ask a question, but it is important that this is done in a non-confrontational or non-inflamatory manner, otherwise discussions soon become mute, personalities soon take over and people (visitors and posters) become disinterested. With a new forum such as this we have a unique opportunity to show how it should be done.

When thinking about answering a post in an inflammatory way, just think about how you would like your posts answered: in a friendly and informative way or in an agressive and confrontational way.

It is not about he said, I said, he said.... its about getting along and having fun.

HAVE FUN,

JOEY.

 

Don't be. There will always be someone like that., posted on November 19, 2002 at 05:12:00
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
But your question is still very valid.

TTFN, John

 

John C, you consistently amaze me, posted on November 19, 2002 at 05:34:50
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""John Es, you ask me to be polite, yet you 'snipe' at my efforts, just like you did with Dr. Hawksford.""

Snipe? Actually, I asked a legitimate question. One which you are unprepared to answer, so you deflect. Why do you take offense to legitimate questions?

Any it seems YOU are the only one on the planet (you know, EARTH?) who has a problem with my questioning the techniques of Dr. Hawksford. HE CERTAINLY didn't. He thanked me for the polite inquery, in fact, and we are discussing the issue. But YOU already knew that as he copied you on the response.

""I KNOW what I am measuring, and every cable type has a different spectrum. I am learning something here""

I have made no assumptions or statements as to what you know. Perhaps you are learning something here, that's not my call.

"" and you are not teaching me anything.""

You state the obvious; everyone knows that.

""Please! Read a tech. book, ask your associates down the hall about things, or ACTUALLY measure something yourself.""

Unfortunately, the "tech books" are not advanced enough to cover the "actual measurements" that I am involved in on a daily basis. But you are welcome to come to PAC 2003 in Oregon, in May, and listen to my presentation on 11 axis motion control superconductor winding techniques for IP solenoid final focussing multiple harmonic cold masses. But before you do, I'd recommend some reading so that you will at least have seen some of the words I will be using. Not understand, mind you, just at least be able to say "hey, I've seen that word before".

Of course, your befuddlement at what I will be presenting would be the exact same thing I went through when I first started here. Took me a year and a half until I knew what they were saying.

I would venture to say, there are many disciplines out there you and I would both be befuddled at. Not a good thing, not bad. Just is.

""Chipping at my efforts does nothing.""

I do not chip at your efforts.. I applaud them.

""Your 'opinion' is no better than that of any layperson.""

Of all you rambled of here, that is the closest you have come to truth.

TTFN, John

 

Re: Cable Test Method, posted on November 19, 2002 at 05:43:10
eico1
Audiophile

Posts: 62
Location: nocal
Joined: November 12, 2002
Yes about the mono source, but the idea is to use left minus right mode of the preamp so only the differences are amplified, not toswitch between the channels. This elimates any need for dbt because you either hear an audible output or you don't.

You can also connect this signal to your scope, pc based fft or whatever to analyze.

steve

 

Re: Cable Test Method, posted on November 19, 2002 at 07:55:16
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Joey, the test MUST be done below 0.1V because it is a type of xover distortion that I am measuring. It goes away at higher levels, because the distortion is only occuring at the xover of the AC signal, near zero volts. This is why it has not been easily noticed before, by many others. Of course, this makes it a noisier environment and that was my challenge. My most effective test signals are between 10mV and 50mV. Above this level, this sort of distortion drops proportionally.

 

Re: I'M SORRY I ASKED.........., posted on November 19, 2002 at 08:28:45
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Joey, you appear new to the asylum. I appreciate your input and your enthusiasm. Still, this has been going on for years, and I have certainly lost my patience. We have been arguing the same points for at least 4 years, either here or on AR, with many of the same people. I have been going through old responses that I made years ago, and I actually was more polite. Yes, I have changed, but I will still try to keep civil enough not to be completely ineffective with others.
Many people think that cable measurements are a waste of time, because they are so subtle. Others have listened to cable differences and that is enough for them, as they trust their ears. I have heard differences, but I would prefer to measure what I hear. That is why I researched and published technical papers on TIM, capacitor linear (DA) and non-linear distortion, and any other problems such as resistors, volume controls, etc.
If you check the archives of the AES up to about 20 years ago, you will find many interesting research articles on distortion in audio systems. Later work is been stifled, because the folks in power don't like the idea that wires, etc can be important. They just ignore it at the AES, and just throw out criticisms about it when they can. Dr. Toole has been brought up on this website. Dr. Toole made some criticisms of wire differences 15 years ago when I first met him, that were not even part of the program. I am well aware of his position on wires, and I doubt that he has changed much, if at all. Yet some here, almost glorify the guy as the savior of the audio industry! On another thread, a 'double-blind' test by Larry Greenhill was cited. Well, I know that the RESULTS of the test were re-written by Larry Greenhill, in order to get it published. How do I know? Hy Kachalsky (sp) , Larry's friend and co-tester, told me so. He was very disappointed, because of the bias used by the magazine to make sure that the test measured almost nothing useful. How about that folks? Objectivity in action!

 

And still, John C, the question remains unanswered...., posted on November 19, 2002 at 10:32:02
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
So I'll ask again. Is it possible "110dB below 50mV" is below audible for humans?

And I state again...Please refrain from your typical attack posture. I'm not attacking you.

TTFN, John

 

Re: John C, you consistently amaze me, posted on November 19, 2002 at 10:36:29
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
John Es, just to have you understand what I am asking you, I will elaborate somewhat. When I say 'read a book' , I mean a book that might be pertinent to this audio discussion that we have on this website, not your chosen field of activity. I have pointed out Hummel, Forwood, and Dr. Hawksford's papers to you. Why don't you get your company librarian to help you find them? Of course, you can buy them for yourself, if you wish. They are available. I am pretty sure that Dr. Hawksford's papers are published by someone. Why don't you ask him about it? This is what I do, when I want to learn something outside my normal field of understanding. I don't design wires for a living, I design linear ampllfiers. We are not talking about linear amplifiers on this website, any more than we are talking about superconducting magnets, so I have had to find a few sources outside my normal field of understanding, such as physics books and websites, to further understand how electricity really flows. I recommend it to anyone interested in this field.

 

Re: And still, John C, the question remains unanswered...., posted on November 19, 2002 at 10:50:01
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
This is only one test. IM distortion will give significantly higher numbers. You misunderstand the nature of higher order non-linearity to its effect on listening fatigue. The normal weighting factor is (N-1)! /2 for the harmonic series plug in 7 for N and see what you get.
For everyone:
'The seventh harmonic, however, introduces an element of discord; ... The same is true of the ninth, eleventh, thirteenth and all higher odd-numbered harmonics; these add dissonance as well a shrillness to the fundamental tone, and so introduce a roughness or harshness into the composite sound. The resultant quality of tone is often described as "metallic", since a piece of metal, when struck, emits a sound which is rich in discordant high tones.' 'Science & Music' Sir James Jeans p86 first published in 1937.

 

Read the post BEFORE responding, please..., posted on November 19, 2002 at 11:06:54
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""You misunderstand the nature of higher order non-linearity to its effect on listening fatigue.""

No, I do not misunderstand that. You misunderstood the question.

So, here it is again: Is it possible 110 dB below 50 mV is below the threshold of human hearing.

I did not ask about 7th harmonic, or the nature of higher order non-linearity and it's effect on listening fatigue. Perhaps it is another thread you are confusing this with?

TTFN, John

 

Stop please. You're already too deep; gonna need a helium mix soon., posted on November 19, 2002 at 11:25:21
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""John Es, just to have you understand what I am asking you, I will elaborate somewhat. When I say 'read a book' , I mean a book that might be pertinent to this audio discussion that we have on this website, not your chosen field of activity.""

We are discussing the relevance of measuring harmonics that are 110dB below 50mV. I asked the reasonable question, are you measuring something that humans are capable of hearing.

Your response: ""Please! Read a tech. book, ask your associates down the hall about things, or ACTUALLY measure something yourself""

My response: "I "actually" measure things you cannot even pronounce."

""I have pointed out Hummel, Forwood, and Dr. Hawksford's papers to you. Why don't you get your company librarian to help you find them? ""

You misquote Hummel...You correctly quote Forwood.. You fax me Hawksford's paper, which I now discuss with him directly...What is your point?

""I am pretty sure that Dr. Hawksford's papers are published by someone. Why don't you ask him about it?""

Your memory is short...You were cc'd by Dr. Hawksford when he responded to me. So, your inference that I am unwilling to discuss (or learn) is blatently incorrect.

""This is what I do, when I want to learn something outside my normal field of understanding. I don't design wires for a living, I design linear ampllfiers. We are not talking about linear amplifiers on this website, any more than we are talking about superconducting magnets, so I have had to find a few sources outside my normal field of understanding, such as physics books and websites, to further understand how electricity really flows. I recommend it to anyone interested in this field.""

Sage advice for anyone.

I look forward to rational discussion with you. I hope I live long enough to witness it.

TTFN, John

 

Very Intresting, posted on November 19, 2002 at 12:03:36
NEAR SOTA
Manufacturer

Posts: 2613
Location: MAINE USA
Joined: July 27, 2002
That is something that most people here did not know JC and it was worth posting it.

I lost all faith in Stereophile with the exception of some of their mesurements of components,but their opinions have hurt alot of good Companies which have gone belly up because of their BIAS'd attitude.A real shame.

Hearing is believeing I guess.That is what I have found in regard to taking the S-philes word.If they like a piece of equiptment I would rather go hear for myself weather there is any truth to it.More often times then not there is better components than the ones they recommend and for less.Could be the tweeker in me.Laughing!

JMO

 

Re: Stop please. You're already too deep; gonna need a helium mix soon., posted on November 19, 2002 at 12:17:03
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Again, I will try to convey my meaning. Why don't you ask Dr. Hawksford about ALL OF HIS PAPERS on this subject. Then you will have CLEAR AND COMPLETE COPIES of his work. What you asked Dr. Hawksford is regarding ONLY what I sent you, and then you complained about its print quality. If you want to dispute his measurements, it seems only fair that you read everything pertaining to his measurements that he has written. That's what Walt Jung and I do, when we have a potential criticism of someones printed input.

 

Re: Read the post BEFORE responding, please..., posted on November 19, 2002 at 12:28:55
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
The testing with a single tone is LESS SENSITIVE. It gives a lower percentage result, than the equivalent multi-toned IM test waveform like the one that Jon Risch uses. However, music IS multi-toned. Unfortunately, my thd meter that does a 90+dB pre-null of the single test tone, cannot null other tones at the same time. If someone will fund me, I will build a multi-toned pre-null box to null a series of spaced tones in front of my HP-3563. Then I can get even larger levels of distortion residuals. However, I am happy enough with differences between connecting wires at the moment.
Now for the rest of you out there. It is true that these levels are low, BUT they are consistent, and change with each type of wire tested. This is real, not guesswork. I am sure that they correlate to subjective listening response to some degree at least, because the 'lousy' wires usually measure much worse than the hi end wires that I have tested.

 

You know, below a certain depth, the helium mix doesn't work, posted on November 19, 2002 at 12:55:13
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""Why don't you ask Dr. Hawksford about ALL OF HIS PAPERS on this subject.""

I am in direct discussion with him regarding those, and have asked him of it, and I quote(my text to Dr. Hawksford):

""Because the situation I encountered fits exactly your Fig. 7, I contend (politely, of course), that it is possible you may have seen a measurement setup error. Given the age of the paper,have you delved any further into the subject?" And, I would like your opinion of my analysis.""

Now, if you look closely, you will see the words "Given the age of the paper, have you delved any further into the subject?" I hope it will not be necessary to explain to you what that means.

""Then you will have CLEAR AND COMPLETE COPIES of his work. What you asked Dr. Hawksford is regarding ONLY what I sent you, and then you complained about its print quality.""

I lamented the lack of discernability of the paper overall, but did not assign blame. Rather, I thanked you for your efforts. And what was readable to me was sufficient to ask intelligent questions of Dr. Hawksford.

""If you want to dispute his measurements, it seems only fair that you read everything pertaining to his measurements that he has written""

I asked him if he had delved further.

Dr. Hawksford appears to be most comfortable with my questions. He is most kind, and has taken the time to respond to me.

You, on the other hand, are obsessed with being the alpha male with respect to all things audio. Why you continue to harp on the Hawksford thing is beyond me. No, actually, it's not beyond me. You use "chaff" in a consistent and predictable manner to divert the conversation so you do not have to address a question you are unable to answer. Again, the question on the table is "is 110 dB under 50mV within the realm of human hearing."

I feel obliged to remind you..."I don't know" is an acceptable answer. I've had to use it many times in my work environment, and am very comfortable in the understanding that others may know more than me. Perhaps there IS something I can teach you after all?

TTFN, John

 

mud measurements., posted on November 19, 2002 at 13:02:50
John Escallier
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Posts: 4425
Location: Long Island
Joined: October 3, 2002
""Now for the rest of you out there. It is true that these levels are low, BUT they are consistent, and change with each type of wire tested. This is real, not guesswork. I am sure that they correlate to subjective listening response to some degree at least, because the 'lousy' wires usually measure much worse than the hi end wires that I have tested.""

There, that wan't hard now, was it??

You have no hard data to back it up your assumption that signals that low are audible, but you express an opinion. That's fine.

And I have no issues with your ability to test signals that low in the "mud", re:real vs guesswork.

TTFN, John

 

Re: You know, below a certain depth, the helium mix doesn't work, posted on November 19, 2002 at 14:50:25
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
John Es, I have answered you in every way that I can. Of course, exactly what I am measuring should be lost in the program material. If we were listening all day to continuous 5kHz test tones, I doubt that a different wire would make much difference, BUT it implies a basic non-linearity that is consistent, yet different between different types of wires. Of course, it would be better if I could just do a differential subtraction with live material between a 'high distortion' wire and a reference wire, and I bet that I would find all kinds of distortion, but for now, I must be content with a steady 5kHz signal or an SMPTE IM measurement. The SMPTE IM measurement is about 4 times more sensitive with a similar distortion made with back to back diodes at a 3V level and a resistor in parallel with the diodes and one to ground. It emulates the sort of distortion pattern almost exactly, and the SMPTE IM distortion is about 4 times higher than the same test done with harmonic distortion. I can see this with the push of a button, and I did it today. However SMPTE IM distortion outputs at 60 Hz intervals and at very low measurement levels,this tends to get mixed up with any ground loops in my set-up. This will take time to untangle. My 5kHz tone has an 18 db/oct 400Hz hi pass filter that removes most of the grounding garbage, so it has not been a problem so far.
So subtract 10-12 dB from my original meaurements of about -110dB and you get -98 dB This is progress. I am sure that if I can use multiple tones that I will then get 'triple-beats' that will be even more obvious in the measurement, and at higher levels too!
For the record, you asked Dr Hawksford for any later work, BUT you did not ask him for the original work that he did on what you are critical of. That is what I think that you should read.

 

Re: mud measurements., posted on November 19, 2002 at 14:52:28
john curl
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Joined: May 16, 2000
No, I just have my ears.

 

I missed your point the first time..., posted on November 19, 2002 at 15:04:44
JOEY.
Audiophile

Posts: 90
Joined: August 11, 2002
Hello Steve,

I missed your point the first time, when you said l-r control. I interpretted this as your suggesting to use the balance control, hence my insistence on a mono source. It is now clear to me that you meant l-r (left MINUS right) in which case you should stick with a stereo source or you would have zero left MINUS right signal. Sorry about the confusion.

Now that you suggest the l-r option, you could build on this further and use the amplifier as a differential amplifier (exactly as I do with my oscilloscope differntial amplifier), by feeding the test signal or music to say the left input, via a T (double RCA adapter at the left input) and then connecting the cable under test between the left input T piece and right input. This with the amplifier set to left MINUS right, you could listen to the DIFFERENCE between cable input and output or view it on a scope. Unfortunately, the channels in the amplifier will probably not be matched well enough in gain and phase to make this possible. I will give it a try some time.

Thanks for your input.


HAVE FUN,

JOEY.

 

Should I just yell "PULL"??, posted on November 19, 2002 at 15:08:33
John Escallier
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Posts: 4425
Location: Long Island
Joined: October 3, 2002
I am cognizant and understanding of the technical issues surrounding the measurements you are attempting. And, I appreciate them.

As for Hawksford, why do you bother? He is more than capable of speaking for himself, far more capable of discussing the issues I raise than you. And he is in a far better position to understand what it is I am questioning than you. And he does not share your concerns.

If you choose to defend him from "horrible, questioning people" like me, I think it may be necessary for you to actually understand what you are talking about, not just read it.

Your best option is to stick to what you know..

As my "hero" Clint Eastwood once said,, " a good man knows his limitations".

I hope that at some time in the future, I may be able to call you a "good man".

John

 

"Just ears", posted on November 19, 2002 at 15:14:16
John Escallier
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Posts: 4425
Location: Long Island
Joined: October 3, 2002
""No, I just have my ears.""

And given your experience and status, I would listen to any opinion you would give concerning what you hear.

Technical issues... That's the easy stuff.

TTFN, John

 

Re: Should I just yell "PULL"??, posted on November 19, 2002 at 15:17:32
john curl
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Posts: 4708
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That is why I sent you to him.

 

Posters of clay..., posted on November 19, 2002 at 15:30:43
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""That is why I sent you to him.""

And that is much appreciated. As was your fax (two actually) to me. Thank you again.

But to continue to raise the "Hawksford issue"? Or Hummel?? C'mon, get real..you speak of things you have not demonstrated the ability to understand. Not good, not bad. Just is. (gee, I've heard that before).

Please stop referring to Hawksford...Or Hummel. It is simply "chaff", nothing to do with the subject...You have placed yourself in an untenable position, one which you cannot talk yourself out of. So stop trying....

If I have an amplifier question, I'm told you are THE MAN!!

For E/M theory, You are over-extending yourself. Big time...

TTFN, John

 

Ooooooh, I forgot........, posted on November 19, 2002 at 17:15:09
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
Walt Jung

Walt Disney

Walt Cronkite

Walt Whitman

I eat lunch with 3 nobel prize winners. But I don't drop their names..

Course, they sit at the table next to me, and haven't a clue as to who I am....They have far more important things to talk about... like bicycling in Nantucket.

I'm sure Walt Jung doesn't appreciate being associated with ridiculous assertions. Course, he doesn't know about it, does he??

When I need analog, IC type circuits; I go to Jung. Best in the world, no question.

When I need E/M analysis? Not you. Why bother with the name dropping? I'm not impressed.

TTFN, John


 

Thanks guys, that was interesting. [nt], posted on November 19, 2002 at 17:16:55
nt

 

Interesting isn't the word for it...., posted on November 19, 2002 at 17:21:35
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
My stomach is killin me.

Steve, thanks for sittin back and watching.

TTFN, John

 

Re: Ooooooh, I forgot........, posted on November 19, 2002 at 17:32:33
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Of course he does, we talked this week. We are writing an LTE together. Get real, please.

 

Re: Ooooooh, I forgot........, posted on November 19, 2002 at 17:39:42
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
I look forward to reading how Walter Jung believes humans can hear 7'th harmonics (35 Khz, wasn't it?) at 110 dB below 50mV levels....

Course, that won't happen, will it?

Stop dropping names. You've lost all credibility.

TTFN, John

 

I'm impressed..., posted on November 19, 2002 at 17:43:33
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
LTE...Letter to the editor??? WOW!!!

Truly impressive...

Course, it's about that cap article, isn't it?

Not what we speak of..


Nice try.

TTFN, John

 

Now maybe you understand why intelligent people..., posted on November 19, 2002 at 17:53:09
kuribo
Audiophile

Posts: 1759
Location: sw wi
Joined: June 27, 2000
like Steve Eddy have given up trying to engage this man in rational, mature debate. It is a waste of good time...

 

Re: Now maybe you understand why intelligent people..., posted on November 19, 2002 at 17:58:48
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""like Steve Eddy have given up trying to engage this man in rational, mature debate. It is a waste of good time..""

"Rational, mature" has little to do with it.... But, boy is it entertaining...

Somebody has to explain reality to him...

All I know is...My stomach is killing me..

TTFN, John

 

Re: Now maybe you understand why intelligent people..., posted on November 19, 2002 at 19:43:32
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Folks, this is my reality.

I originally used zip cord and Switchcraft prefab interconnect in the '60's and '70's. Then Polk introduced 'Cobra' cable and I tried it. It was different sounding than zip cord, or 14 ga Belden cable that I also had. Then, in 1978 I bought 'just for fun' a 1M silver cable in Japan when I was there. I listened to it, my girlfriend listened to it, and a hi fi store listened to it. We all found it 'bright' sounding. Later, I was approached by a couple of guys from Mendota Research with shielded litz / teflon cables and we found them very good sounding. Harry Pearson also found them good sounding. Years later, a firestorm destroyed my apartment building, so I had to start from scratch. At first, I just bought Radio Shack cable and listened with what equipment I could buy used or was given to me. It always had a slight electronic edge. Later, a cable manufacturer (not in business at this time) gave me a number of interconnect cables to use. They were better than the Radio Shack cables, but I did not know why. I kept the Radio Shack cables around for my test bench.
Then I determined that I might just be able to measure what Dr. Van den Hul had told me about. I measured difference in cables and interestingly the Radio Shack cables measured worse than many others. Still, I had a lot of noise and RFI that made it difficult to show others what I had measured. Recently, I purchased a special FFT based instrument that can resolve wire differences easily. That is what I am measuring with today.
Is it important, is it useful, is it worth my time? Heck if I know, but then DA and TIM were ridiculed at first, but we plodded on anyway. Later, others have tried to take credit for our efforts, and we have had to write formal letters to clarify our original research.
I expect to do so in future, with this kind of cable nonlinear distortion. My position is that people that I trust can easily hear differences in cables and that there must be something that is measurable about them. I am attempting to make these measurements, rather than tell my friends and associates that they just have overactive imaginations, like so many on this website are attempting to do. We do not progress, if we ignore what we can hear with good audio equipment.

 

Re: Now maybe you understand why intelligent people..., posted on November 19, 2002 at 22:00:11
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
1. All the people on this website can appreciate the effort you are putting into resolving cable differences.

2. All the people can empathize with the trials and tribulations you have experienced.

3. All on this website, to date, have accepted the fact that cable differences exist. Why else would they be here?

4. All the people on this website should be tolerant of differences of opinion, without the unprovoked "attack posture" you have shown such willingness to use.

5. All the people here have the intelligence to ask questions of tests and research being done and presented. To blindly accept as gospel anything presented here is probably not going to happen without proof, repeatability, or verification.

6. All here, I'm confident, wish you well in your efforts.

7. And finally, all here would prefer a more civil discourse.

I have only been critical of your posturing and attacking, and have responded in kind to your postings. But I prefer civility.

Thank you.

John

 

Re: Now maybe you understand why intelligent people..., posted on November 20, 2002 at 07:05:02
I am posting the following against my better judgment (a behavior pattern, BTW, that is not uncommon for me, unfortunately).

My position is that people that I trust can easily hear differences in cables and that there must be something that is measurable about them.

That’s all well and good for you as a design engineer. You trust your hearing and that of others, so you believe this approach works for you. I can't imagine anyone here who would want to try and tell you how you should approach design. However, from the viewpoint of scientific validation, that approach just doesn’t cut it.

You have made it perfectly clear that you have no interest in scientific validation through DBTs. Again, that’s fine and that’s your prerogative. However, that, in my opinion, is no excuse for you to deride and demean those of us who do have an interest in it. To do so, again in my opinion, tarnishes both your credibility and your reputation. But, as it affect me personally, it is also undermining the potential we have at this forum to allow all points of views to be expressed and discussed in a civil manner.

I am attempting to make these measurements, rather than tell my friends and associates that they just have overactive imaginations, like so many on this website are attempting to do.

I am well aware of the attitude you are describing here. I have commented at length, and been subjected to severe criticism, at AR regarding the intellectual arrogance of some extremist objectivists. But I have not seen such attitude expressed on this board yet. In my opinion, most people here are attempting to respect opposing views and carry on discussions that are aimed at spirited debate and questioning of different viewpoints, while avoiding intellectual arrogance and personal attacks.

My own personal listening experiences with cables is very similar to how you have described yours. But I’m also interested in exploring this issue from a dispassionate, objective viewpoint. I have found your descriptions of the measurements you are attempting to make informative and interesting. I just don’t understand why you have to attack those who raise legitimate questions regarding the relevance of such measurements to audible sonic differences.

 

Re: Now maybe you understand why intelligent people..., posted on November 20, 2002 at 10:39:48
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
Phil, this is part of what I wrote about DBT in 1979 !
This was an LTE to Dr. Lipshitz et al in TAA.
3/1979 pp 61-62
PARALLELING, MAGNETICS & Z

'A double blind listening test, while removing a subjective bias toward hearing differences that may not truly exist, unfortunately does nothing to remove bias toward NOT hearing any differences that may actually exist in equipment. Indeed a double blind testing situation could intimidate listener not to take a stance, since one could be embarrassed, if misled momentarily by a change in the quality of timbre of the musical source, to make what would seem to be a random decision. It seems we must invest a certain amount of faith in the objective integrity of the listener in any case. In conclusion, while I applaud any efforts to remove some of the inconsistencies in the listening tests, I believe a more technically accurate approach must be taken to correctly evaluate differences between equipment, that one must be willing to accept that others in the industry are also attempting to clarify understanding of the listening process. Ultimately, I hope that we can work together to advance audio design beyond the mysticism and sales hype that is present in so many instances, without irresponsibly disparaging much of the serious research aimed at improving the sonic qualities of existing audio equipment.'

I still stand behind my original statement.

 

Re: Now maybe you understand why intelligent people..., posted on November 20, 2002 at 11:16:51
John:

I certainly agree with that. It seems to me (based on my limited knowledge of the subject) that, while people like jj may have refined DBTs for their specific purposes not directly involving high end audio, there has been little effort expended to address the concerns you expressed with DBTs back in 1979. It was the limitations upon the current state of the art in blind testing as it applies to high end audio, as much as anything, that I hoped would get explored on this forum.

I have a new power line conditioner in my system that I've been experimenting with (sighted auditions). I'm amazed at the sonic differences I perceive in trying different combinations of equipment plugged in to my existing PLC and the new one.

To the absolute best of my knowledge, I have no preconceived expectations with respect to either PLC, and certainly none with respect to the various combinations I am trying. I would be shocked if the degree of differences I'm perceiving weren't real, and I will settle on the combination that works best for me based on my sighted auditions. On the other hand, because my own personal choices haven't been be validated scientifically, I won't be making any absolute claims about the effectiveness of either PLC. I may, however, with the appropriate disclaimer, share my impressions of both.

I understand there is no need for you to justify to me or anyone how you proceed in your research and design efforts. If I were a designer myself, I'm pretty sure I wouldn't bother with DBTs either. But I am curious enough to hope that someone will refine the blind testing process as it relates to high end audio, and, for once, perform some DBTs that, regardless of outcome, there can be common agreement as to the validity of such tests.

 

John..., posted on November 22, 2002 at 01:47:36
Sean
Audiophile

Posts: 4342
Joined: October 9, 1999
Being familiar with a lot of your work and behind the scenes research throughout the years, i believe you 100% when you say that you are doing your best to try and understand and explain how / why things work the way that they do. There is no doubt in my mind that you put forth every effort possible to know and learn as much about audio electronics that you can. In doing so, i sometimes think that you take for granted that others may have the same level of understanding and / or desire to know what you know and that is simply not the case.

Having said that, i did not take John E's initial response to you as being confrontational. I think that he was asking "how far does one have to go before we are sure that it is or isn't audible ? Are we barking up the wrong tree here? ". While i can see how you could take this as saying "this is so low, you are are wasting your time", i don't think that he meant it that way. I think that he's REALLY trying to figure out WHY cables sound different from one another and how we can document / analyze those differences. After all, he does acknowledge that cables DO sound different from one another.

I hope that you take this in the manner that i meant it to come across. I and many, many others here appreciate your efforts. At the same time, we also appreciate the efforts of some of those that tend to disagree with you. It is possible for even an imbecile like me to make sense once in a while and be able to help someone out. Let's try to keep things in balance and maybe we can make progress rather than enemies. If we don't understand what someone is trying to say or their post can be taken in several different ways, let's try asking for clarification rather than going off on what might simply be a misunderstanding. I'd like to continue learning from you and all the others that are willing to share but don't want to have to wade through posts and sometimes entire threads of nothing more than contempt to do such. Sean
>

 

John and John, posted on November 22, 2002 at 19:20:51
Penguin
Audiophile

Posts: 7116
Location: Delaware
Joined: August 5, 2001
would you two give it a rest? This is not productive. I would expect the two of you to have alot more productive discussions.


dee
;-D

 

Re: John..., posted on November 23, 2002 at 09:57:08
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
I stand behind my first statement on this issue. John Es was 'sniping' at my efforts, without giving any more than his opinion about audio. This is a guy that looks up to K-horns! Been there, done than, even analyzed them. Know better today. Enough!

 

John Curl, you still grabbing at straws??, posted on November 24, 2002 at 10:16:17
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
Sean is correct.

K horns? Haven't had them since, oh, was it '81 , or '82? Who knows..Nobody cares except you. But you simply had to grab at anything in your feeble attempts at climbing to the top of the sandbox, regardless of who you have to step on. You are apparently losing sleep over the possibility someone else knows more than you on ANYTHING, not just audio. Reality is a brick wall you desparately try to avoid hitting, but eventually.....

""John Es was 'sniping' at my efforts, without giving any more than his opinion about audio""

Gee, John Curl.... Any possible shot in the dark, I see. I did not give my "opinion about audio" I asked you a simple question. Was 110 dB below 50 mV within the ability of human hearing. You sideswipe to avoid answering the obvious...It isn't. But that would prove your efforts to date useless...HORRORS..

One can only hope that you someday decide to think rationally in respect to audio. You certainly don't when it comes to posting.

If you wish for sniping, I'll certainly be happy to accomodate. Here's a small sample.

FFT based analyzers of the type you have purchased, are incapable (for math reasons beyond your understanding) detecting the type of signal you are looking for. That's why you are looking in the mud, below the noise floor of most typical amplifiers, as well below human hearing, especially at 35Khz.

What you are practicing, in the nomenclature of upper level academics, is called "Ice Cream Science". Shark attacks occur at the beach...Lots of ice cream is sold at the beach...They correlate, therefore, if you stop selling ice cream, shark attacks will stop.

I've been quite content to date to not address all the ridiculous, preposterous, unfounded, unscientific, unverified, untestable, unrepeatable and untrue theories you have provided this audience. I had not thought that was warranted. But I can see that you tend to use everybody's lack of understanding of subject areas outside of their expertise to your advantage. "New physics"??? I have no problem calling any more of that garbage to the table, John.


As you can see, I'm getting less and less tolerant of your posturing, and may in the future find it necessary to shift into "second gear". Trust me, not a pretty sight.

As for now?? You are at level one. And going backwards..

As I have repeatedly stated, I would prefer a professional atmosphere. Act professional, for a change. And stop whining.

TTFN, John


 

Re: John Curl, you still grabbing at straws??, posted on November 24, 2002 at 11:07:41
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
John Es, you have accused me of 'whining' and I have accused you of 'sniping'. Let me define what I mean by 'sniping'.
To me, 'sniping' is the criticism of someone elses research without attempting to verify or ascertain whether your criticism has any merit. So far, you have 'sniped' Hummel, Hawksford, and me, in that order.

For me, 'sniping' is related to 'refereeing' because that is where it does the most damage.

For everyone, this is what happened at an IEEE Conference on TIM at Tulsa in 1978. Walt Jung and I had completed giving our respective papers on (TIM or SID) when Walt recognized Dr. Ashley in the audience. He asked Dr. Ashley, in front of me, why Ashley had rejected his paper written specifically for the 'Journal of the AES' where Dr. Ashley was a referee at the time. Dr. Ashley responded that "he didn't like the math". He was referring the the 'Volterra series'. Dr. Ashley didn't try to PROVE that there was anything wrong with the math, and he never did show that anything was wrong, he just expressed his uninformed opinion.
I knew something about the 'Volterra series' because I studied it at UCB in the same graduate class as the co-author of Walt's Paper and this is where it had originally came from. Walt's paper wound up published in 'The Audio Amateur' and this started a long tradition of using alternate venues, rather than the AES.
This is 'sniping' folks.
As far as my measurements are concerned:
Engineers know that the underlying basis of any harmonic distortion is a deviation in the transfer function, which ideally should be a straight line. I am looking for 'kinks' in the transfer function. Harmonic analysis is one of the LEAST SENSITIVE methods of measuring the underlying non-linearity, but it is relatively easy to do, and we can measure extremely low levels, BECAUSE we can null the original signal. Actually, a multitone IM signal would be better, and real music would be better still.
Fortunately, a single harmonic can predict that there is an even greater amount of distortion generated with real music, but I just can't directly measure it at this time.
It is also true that I am using a 5kHz signal, for convenience. I could use a 500 Hz signal and then the 7th harmonic would fall at 3500 Hz. However, my THD analyser is 25 years old and does not want to null at 500 Hz without me readjusting it, while also measuring at the LOW LEVELS necessary for this test. The non-linearity that I am measuring will track with frequency. At higher input levels, the distortion goes away, as this a crossover type distortion, rather than a simple nonlinearity, so I am running my distortion analyser at its operational limits. This is why this sort of distortion in wires goes unnoticed,because nobody looks at wires at lower voltage levels, where they actually operate in audio systems.
To criticise my efforts at this point is 'sniping' as you have refused to consider what I just stated, and your intent is to block my input rather than to constructively criticise it. I knew this from the first, so I originally responded as to your 'intent' rather than the specifics of your question. I hope that this clarifies the situation, however, I will always have critics just like my friends. Oh well. ;-)

 

It would seem so.., posted on November 25, 2002 at 06:04:33
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""To me, 'sniping' is the criticism of someone elses research without attempting to verify or ascertain whether your criticism has any merit.""

Criticism of someone elses research hasn't happened within my posts. You react to a question you do not wish to answer by calling it sniping, and then deflecting the issue, dropping names, saying "read a book", criticising education, saying "oh, I proved that wrong 20 years ago", ad nauseum. People will soon be passing around the "top ten reasons John Curl is better than I" list. Humor is always the best medicine.

Criticism...no.. All I asked was "" if 110 dB below 50 mV at 35Khz was audible to humans.""

That is not criticism. Criticism is: "what you are testing is BS, you are stupid, you don't know what your talking about, your mother wears combat boots." A simple, nicely worded question is not that.

It may indeed prove out that the "measurements in the mud" you are doing correlate to the real issue. Then again, it may not.

Your attitude is not one of a professional. Is it any wonder a lot of the big names don't frequent this forum? To be constantly on guard lest John Curl feels impinged upon?

As you can see, I don't live my life worrying about you. You can be right at times, wrong at others.. I also "own" the same subset.


""So far, you have 'sniped' Hummel""

You misquoted him, then beat everybody down with your "new electron physics" mumbo jumbo, which I am ridiculed about whenever I bring it up to a real physicist. And you still are unable to answer the question I posed with regard to that "physics", a simple, high school level question. How long did you spew that stuff on this forum??? And how many people were beginning to believe it??

""Hawksford,""

I identified a possible testing error, and discuss it with him. Pointing out an error in research is mandatory for the advancement of science. Blindly accepting incorrect analysis and testing methods is the quickest way to bring scientific advancement to a halt. I'm beginning to believe more and more that that is why you do not like peer review.

""and me, in that order""

YOU??? I hadn't sniped. You can believe what you want. I find a lot of your "postulates, or pseudoscience" to be beneath response. Unfortunately, those here without E/M theory background might actually believe some of your "interesting" theories...That "faith" based system is better suited for religion, not a technical forum.

Having papers not accepted for personal reasons is unacceptable, your story is interesting, and worthy of public review. But has nothing to do with your continued unprofessionalism..It's not a valid excuse.

My definition of whining? Read all the posts you have made in response to one of mine. THAT is whining. And that is unprofessional.

TTFN, John

 

Touche!!!!, posted on November 25, 2002 at 07:40:56
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
My feelings exactly. I would prefer professionalism.
And have tried my best over the last month not to offend Curl, constantly attempting to "toe the line" to placate him.

But the constant barrage??? And not only against me.

And the realization that should his "idols" come under scrutiny (Hawksford, Hummel), he should not find it necessary to fire volleys. But, instead, to engage in productive dialogue. His "idols" may not always be right, everybody should keep an open mind.

He always fires, and then, eventually, backs off and gives reasons for his attacks (peer review experience, refereeing problems, lack of credit where credit is due, being attacked in this forum, etc.

One tires of the bipolar attitude. I prefer easy, technical issue based discussion. And not being told to "read a book", "welcome to the real world of physics", and all the rest.


""would you two give it a rest?""

I would prefer it that way...But it takes two...I have not, and will not attack unprovoked...But it takes two.

Perhaps the moderator should step in whenever unwarranted, non-technical diatribe starts? But that does raise interesting censureship issues.

Like I said, it takes two...


Thanks dee, bout time somebody said something.. John

PS. You know, as long as it stays competitive and not personal, that's a very good thing..

 

Re: It would seem so.., posted on November 25, 2002 at 09:26:24
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
John Es, I have only one nagging question. The rest I can ignore. That is: When and how did I misquote Hummel?
For the rest, it is amazing how many individuals can find 'research errors' in other peoples work, yet not do anything themselves to prove with any evidence of an oversight being actually made. This is what Dr. Ashley did, almost 25 years ago to Walt Jung, and allegedly blocked Walt's 55 page preprint from being put in the AES Journal. It is interesting that Walt Jung is now awarded for his efforts over the years, but when you are an innovator, trust me, you can easily be blocked by those who would take the credit themselves, or stop you just because they cannot change their paradigm of what they think is important in their area of expertise. Just for fun let me quote you a few examples:
"There is no reason for any individual to have a computer in their home" Ken Olsen Pres. of DEC 1977

"I can accept the theory of relativity as little as I can accept the existance of atoms and other such dogmas" Ernst Mach 1913

"X-rays are a hoax" Lord Kelvin 1900

 

John, do you read your e-mail??, posted on November 25, 2002 at 10:28:38
John Escallier
Audiophile

Posts: 4425
Location: Long Island
Joined: October 3, 2002
""John Es, I have only one nagging question. The rest I can ignore. That is: When and how did I misquote Hummel?""

Well, it's about time. You passed that for a while.

Sent you an e-mail...Please read it.

I will not address any of this post or any other ""attack"" posts from you until you have done so.

Let me know if you didn't receive it. The system here had no problem sending it, or at least telling me it was sent.

Thanks.

Cheers, John

 

Re: John, do you read your e-mail??, posted on November 28, 2002 at 10:22:16
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
John Es, I answered your E-mail, not how did I 'misquote' Hummel? For the record, my test load is about 4K ohms.

 

Re: John, do you read your e-mail??, posted on November 28, 2002 at 10:57:33
john curl
Manufacturer

Posts: 4708
Joined: May 16, 2000
John Es, I answered your E-mail, not how did I 'misquote' Hummel? For the record, my test load is about 4K ohms.

 

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