Hi John,
What you understood about capacitors 25 years ago was also known by quite a number of other people. Certainly in the test and measurement fields, and also by some people in this field. Hearing you whine about "having to continually go back 25 years" is very self centered. I go back over 25 years every time I help a person new to electronics. Big whoop! Okay, so you don't like to pass on your knowledge I guess. So stop crying about this. Of course you later go on to say ....
You have a number of very intelligent and accomplished people around you. Realize this and start communicating with people as an equal. I don't see you as having more skills than some other people around here.
Sorry John, but the way you talk to other people is reflecting badly on you. I find this sad for a person who has done as much as you have.
-Chris
I know this post is from way back, but it is this type of post that you make often that shows deep disregard for your contemporaries and people who would like to learn. This thread is moving faster than I can keep up these days.
What you understood about capacitors 25 years ago was also known by quite a number of other people. Certainly in the test and measurement fields, and also by some people in this field. Hearing you whine about "having to continually go back 25 years" is very self centered. I go back over 25 years every time I help a person new to electronics. Big whoop! Okay, so you don't like to pass on your knowledge I guess. So stop crying about this. Of course you later go on to say ....
Now, that is a scary comment. You are afraid they might come up with reality on their own? Or is it easier to indoctrinate slack-jawed, drooling idiots who have no thoughts of their own? The lack of respect you continually show others around you are stunning. How would you like to be treated John?
You have a number of very intelligent and accomplished people around you. Realize this and start communicating with people as an equal. I don't see you as having more skills than some other people around here.
Sorry John, but the way you talk to other people is reflecting badly on you. I find this sad for a person who has done as much as you have.
-Chris
andy_c said:
Andy,
You have me at a disadvantage here... but what I read (and I may have to re-read it) was that with the GedLee metric he was able to show that the metric predicted or showed that amps of widely different "distortion" measurement would sound indistinguishable, as would/could amps of very similar "distortion measurement" sound different or the same (depending on the Metric.)
Is this not correct?
I am unclear what you mean when you say that he imposes distortion digitally, as I do not know the mechanism he employs to actually do the "Metric's" measurement. I only know what he wrote on his website, not what was in his papers or his book.
Certainly D.E.L. Shorter mentions spectra...
So, where in the real world does the criteria for the Metric lie? Or what is the real world difference between amplifiers that the GedLee reveals?
I'm only too happy to get it right and be corrected.
_-_-bear
Hi Grey,
Just because I can look at a project objectively does not mean I don't enjoy listening to music. I have a two channel listening room because I love good music.
Once I get a project running on the bench, I make measurements before wasting my time running up and down with it. There is also an audio system on my bench that gives me a good idea how something sounds. Also, I don't simply measure THD. I look at the residuals on my 'scope and also on my HP 3585A Spectrum Analyzer. So you see, I know how to interpret what I am measuring and it isn't a simple THD figure.
People who know me in person also know that I don't judge my own work. I tend to be too hard on myself. The most honest answers I get are from children and my wife. She doesn't hold back any punches, all she has to say is "I don't like it". I do not have my mind made up before listening to something.
Question then. If your next prototype of a circuit has higher distortion than the last, don't you first determine what kind of distortion you have? Aren't you concerned or do you just watch things together and go have a listen each time?
People who have studied electronics and committed money for tools, books and education do have more experience than those who don't. They investigate reasons why things sound the way they do. They have been exposed to the importance of valid testing and also how to interpret tests that are uncontrolled. They even understand the laws of physics. No matter how you twist words around, the recreation of music is all physics and obeys all the laws of physics. Wild goose chases happen less frequently in this group.
In contrast we have our subjective seekers. They do not have the understanding of how these things work. They do not understand components, nor are they normally able to properly test their ideas. The result is that you get people drawing around CDs with green markers (I imagine they tried others too). People sticking bricks on top and an entire litany of injustices to equipment inside. People who suspend their speaker wire inches off the floor with cute little stands.
People who don't understand how things work will do the best they can. The unknowns become a quirky science to them, and a religion. Most things reported by subjectivists are non-repeatable and unprovable. If you don't believe, you are looked at with pity, an outsider who hasn't found the truth, will not experience audio nirvana - ever. People will create a belief system to explain what they can not comprehend. It allows them to exercise control over the things they can't explain. In other words, the dark ages.
Now, about old test equipment. Guess what? They had meters and cathode ray tubes. Those old experimenters were also careful to conduct tests carefully. I read book from the 1920's and up, and I can tell from your comments that this was simply another guess on your part.
The only "professional listeners" (subjectivists) I have witnessed are not unsure of what they claim they hear. The honest ones are, but for most, they must be sure to appear knowledgeable to others. The first thing these people will say if you disagree is that your hearing isn't as acute as theirs is. They always fall back on "well, that's what I can hear" and that's the end of that. They are the ones who are closed minded about things. All someone has to do is ask for proof and they will get something like " Oh, well my ears have been trained and they are much more sensitive than any test equipment will be".
How many thousands of dollars will we have to spend in order to provide more accurate measurements to people who dismiss the measurements, when they don't even understand those measuring devices and what the limitations are?
I will say that what the "measurements-oriented folks" accept as fact evolves as the tools and knowledge improve. They just don't normally go lunging off into some wild idea without some reasonable explanations as to why something might be true.
-Chris
That wasn't very nice of you.
Just because I can look at a project objectively does not mean I don't enjoy listening to music. I have a two channel listening room because I love good music.
Once I get a project running on the bench, I make measurements before wasting my time running up and down with it. There is also an audio system on my bench that gives me a good idea how something sounds. Also, I don't simply measure THD. I look at the residuals on my 'scope and also on my HP 3585A Spectrum Analyzer. So you see, I know how to interpret what I am measuring and it isn't a simple THD figure.
People who know me in person also know that I don't judge my own work. I tend to be too hard on myself. The most honest answers I get are from children and my wife. She doesn't hold back any punches, all she has to say is "I don't like it". I do not have my mind made up before listening to something.
You just made a pile of incorrect assumptions. Why did you bother trying to make a point without any facts? All this was an assumption you made. Possibly reflecting your own tendances on everyone else?
Question then. If your next prototype of a circuit has higher distortion than the last, don't you first determine what kind of distortion you have? Aren't you concerned or do you just watch things together and go have a listen each time?
Sure I do. But they are not too often trying to prove something with no evidence. But what you are calling a prejudice is simply a difference of opinion with you. As far as I can see, my normal methods are pretty balanced in approach. I also know from reading many posts from other members here that they have a similar approach to mine. I don't know if you and John are not getting enough useful data from your measurements in order to draw useful conclusions or not. I suspect not, given your stance on things. But you can't assume that everyone else is in the dark as well. That right there might be the difference between a subjectivist and what I guess you could call an objectivist.
Why does this matter anyhow? I would suspect that all these members would listen to their work before accepting that they have got a good amplifier or whatever. There are many posts here where a member has a subjective opinion on various devices.
We disagree. While the precise DC supply voltage in an audio device is not normally critical, some distortion measurements are. I will consider a THD figure as a pass / fail point for a circuit. If something can not pass a THD test, that means that something is wrong. It's broke and needs fixing. What you should be looking at when designing is the raw THD figure, but you really need to be looking at what type of distortion you are seeing. They give you clues where you can improve your amplifier. My experience is that if you can get rid of some obvious distortion, the item will sound better. Normally this also involves setting the operating point of active devices properly. This will sound better, believe me as I have many instances of empirical proof on my bench over the years. I'm sure many others here have similar experiences.
That is a silly group of comments.
People who have studied electronics and committed money for tools, books and education do have more experience than those who don't. They investigate reasons why things sound the way they do. They have been exposed to the importance of valid testing and also how to interpret tests that are uncontrolled. They even understand the laws of physics. No matter how you twist words around, the recreation of music is all physics and obeys all the laws of physics. Wild goose chases happen less frequently in this group.
In contrast we have our subjective seekers. They do not have the understanding of how these things work. They do not understand components, nor are they normally able to properly test their ideas. The result is that you get people drawing around CDs with green markers (I imagine they tried others too). People sticking bricks on top and an entire litany of injustices to equipment inside. People who suspend their speaker wire inches off the floor with cute little stands.
People who don't understand how things work will do the best they can. The unknowns become a quirky science to them, and a religion. Most things reported by subjectivists are non-repeatable and unprovable. If you don't believe, you are looked at with pity, an outsider who hasn't found the truth, will not experience audio nirvana - ever. People will create a belief system to explain what they can not comprehend. It allows them to exercise control over the things they can't explain. In other words, the dark ages.
Now, about old test equipment. Guess what? They had meters and cathode ray tubes. Those old experimenters were also careful to conduct tests carefully. I read book from the 1920's and up, and I can tell from your comments that this was simply another guess on your part.
Yes, they are. However, they are not a proof until you determine exactly what you saw/heard/felt. The testing must be controlled. Don't expect too much intelligence to come out from a bunch of informal guys who go around to each others houses to critique their systems. Once they start hearing things that aren't there, the power of suggestion takes over and you have the latest audio myth. Don't discount the power of not wanting to appear less capable or less informed than others around you. People will say they heard something even if they didn't, only to appear as knowledgeable as those around them. Human nature, and I have witnessed this - it's hilarious to watch!!
Since I just explained some of the reasons for this, or ....
The only "professional listeners" (subjectivists) I have witnessed are not unsure of what they claim they hear. The honest ones are, but for most, they must be sure to appear knowledgeable to others. The first thing these people will say if you disagree is that your hearing isn't as acute as theirs is. They always fall back on "well, that's what I can hear" and that's the end of that. They are the ones who are closed minded about things. All someone has to do is ask for proof and they will get something like " Oh, well my ears have been trained and they are much more sensitive than any test equipment will be".
How many thousands of dollars will we have to spend in order to provide more accurate measurements to people who dismiss the measurements, when they don't even understand those measuring devices and what the limitations are?
Grey! What have measurements-oriented folks had to change their view on??? They were correct for pete's sake! The very fact that people jumped on those band wagons is telling for me. Is your point that "measurements-oriented folks" didn't take the bait?
I will say that what the "measurements-oriented folks" accept as fact evolves as the tools and knowledge improve. They just don't normally go lunging off into some wild idea without some reasonable explanations as to why something might be true.
-Chris
Hi Grey,
Continued ...
-Chris
Continued ...
Yup, lived through it all. But I took courses in physics, chemistry, math and electronics. I had a scientific background and most the these claims didn't ring true. Having some experience in test and measurement, I did know that capacitors sounded differently. No stretch as they behaved differently. The rest of the mumbo-jumbo people came out with provided me with a lot of entertainment. So, what's wrong with that? I don't see your problem, expect that by disagreeing with you, I somehow challenge your beliefs I guess. You are awfully defensive here. Getting personal even.
Got me lost here Grey. I honestly do not understand your point. I do admit I can't keep up with this thread right now, and it takes me a long time to post. There are reasons for that though.
-Chris
This cap DA business is a bit of 'damned if you do, and damned if you don't'. IF I reference my own work from 25-30 years ago, a certain group here gets annoyed, that I go back so far, for references on this subject, BUT that is when the work was done! Of course, there have been some more recent contributions, but they often are not any better than my earlier references, and maybe actually worse, ON THE FACTS that I am trying to relate.
Real dielectric absorption goes back to the '30's to '60's during the advent of the analog computer, BUT it was forgotten, except for special functions, such as sample and hold.
NOBODY did a characterization of the effect of DA and non-linear distortion in coupling and EQ caps in AUDIO, before we did, to the best of my knowledge, and we did that 25-30 years ago ourselves. That includes: Walt Jung, Dick Marsh, and me. We are still being attacked over this early work.
Yet to some here, DA is OBVIOUS, and always was, even for audio applications.
It reminds me of my old refrain:
"It doesn't exist"
"It exists, but it is not important"
"We either invented it or we knew about it all the time"
And so it goes, fellow engineers.
Real dielectric absorption goes back to the '30's to '60's during the advent of the analog computer, BUT it was forgotten, except for special functions, such as sample and hold.
NOBODY did a characterization of the effect of DA and non-linear distortion in coupling and EQ caps in AUDIO, before we did, to the best of my knowledge, and we did that 25-30 years ago ourselves. That includes: Walt Jung, Dick Marsh, and me. We are still being attacked over this early work.
Yet to some here, DA is OBVIOUS, and always was, even for audio applications.
It reminds me of my old refrain:
"It doesn't exist"
"It exists, but it is not important"
"We either invented it or we knew about it all the time"
And so it goes, fellow engineers.
stinius said:
But it has been done. Stereophile locked Bob Carver in a hotel room with boxes of parts and equipment, and he succeeded to modify one of his amps to be indistinguisable from a famous tube amp. I don't have the details right now, it's on the 'net somewhere, but he did exactly that.
I think he manipulated two things: the freq response and the output impedance.
Edit: I just saw that Peter Daniel has put up the link. Sorry.
Jan Didden
Ragnwald said:
BS. That would mean that I need to get real bad recordings to enjoy my ultra-expensive system. Jeez.
Jan Didden
PMA said:
Can you please elaborate on what should be measured?
SY said:
This is basically what I do when testing cables.
Subjetive comparison testings has some failures too
The acoustic ambience
The speaker used
The method used.
The most terrible one is the method...were we can produce many mistakes...if you delay to switch from A to B, more than 3 seconds, the brain will adjust.
I understand Curl... i would never enter that sittuation...because result is not predictable.
Unfortunattelly... the best method is not enougth... there are failures...it is not precise...not entirelly precise.
I suppose your listening tests may have a method.
I found, during my home testings with friends, that i have thousand ways to "manipulate" the results... even the introductory conversation is important... if you show the equipments or not, how famous is the brand, or the designer...this produces advantage.
A friend use to demonstrate equipments into customer home...of course this produces a result..for sure....try to sell equipment using shorts and "T" shirt.... and do not give to the customer full attention to see if you will sell a single unit!
If Curl behaves in a kind way..... people will always prefere his amplifier... this appear clearly into my third world testings...maybe your more civilized countries are less influenced by "human factors"... the opposite is reality too.... say...if he behave unkind.... people will try to trow stones on him despite his great amplifier.
If i was in John Curl's pants... i would never do such comparison or listening tests...because result will be more dependable of his social relationship than the real audio... in this moment, as he was criticised..he will be smashed and transformed into sub extract of evaporated horse gases.
I am with you John..... i can understand you....not full aprovall..but you have my understanding and support.
I have not readed the entire thread...so....i can be wrong about my comments that may not make too much sense to you...if this happens.... please, receive in advance my apologizes....i have readed some pages, in special those last 5 pages.
We adjust our brain, the audio quality depends our WILL...if you want, can be better than reality, or worse.
Your wife is the best world wife... WHY?...because you want that...you do not even know all other wives!
Carlos
The acoustic ambience
The speaker used
The method used.
The most terrible one is the method...were we can produce many mistakes...if you delay to switch from A to B, more than 3 seconds, the brain will adjust.
I understand Curl... i would never enter that sittuation...because result is not predictable.
Unfortunattelly... the best method is not enougth... there are failures...it is not precise...not entirelly precise.
I suppose your listening tests may have a method.
I found, during my home testings with friends, that i have thousand ways to "manipulate" the results... even the introductory conversation is important... if you show the equipments or not, how famous is the brand, or the designer...this produces advantage.
A friend use to demonstrate equipments into customer home...of course this produces a result..for sure....try to sell equipment using shorts and "T" shirt.... and do not give to the customer full attention to see if you will sell a single unit!
If Curl behaves in a kind way..... people will always prefere his amplifier... this appear clearly into my third world testings...maybe your more civilized countries are less influenced by "human factors"... the opposite is reality too.... say...if he behave unkind.... people will try to trow stones on him despite his great amplifier.
If i was in John Curl's pants... i would never do such comparison or listening tests...because result will be more dependable of his social relationship than the real audio... in this moment, as he was criticised..he will be smashed and transformed into sub extract of evaporated horse gases.
I am with you John..... i can understand you....not full aprovall..but you have my understanding and support.
I have not readed the entire thread...so....i can be wrong about my comments that may not make too much sense to you...if this happens.... please, receive in advance my apologizes....i have readed some pages, in special those last 5 pages.
We adjust our brain, the audio quality depends our WILL...if you want, can be better than reality, or worse.
Your wife is the best world wife... WHY?...because you want that...you do not even know all other wives!
Carlos
Joshua_G said:
There is no universal cookbook, and every case is unique. If there was a coobkook of measurements in correlation with subjective psychoacoustic perception, we would not dispute here.
I can only tell you about some measurements that are important to me:
1) very low level FFT, at 10mV - 1V output level
2) measurement of high frequency content in audio signal
3) measurement of mains residuals (50Hz, 60Hz and multiples) and other low frequency noise components, that are almost always higher than THD distortion components
4) time domain step response must not show any residuals of slew-rate limitation for any output amplitude
5) behaviour into very difficult loads, like 1-2 ohm real or 1 ohm + 22R//20mH//500uF, including FFT
6) shape of distortion residual
7) if THD FFT is measured, it must be done for amplitudes starting at some 10mV up to limitation, for numerous base frequencies from 20Hz to 20kHz and into difficult load, not 8 or 4 ohm real.
This is what John is doing all along this thread, passing on his knowledge (but understandably not posting schematics).
There seem to be assumption on your part about "idiots who have no thoughts of their own". Is it possible that some people with knowledge and thoughts of their own would appreciate John Curl as an audio designer?
How do you define "accomplished"?
Do you refer to formal education only?
Are there no educated subjectivists?
To your view, is technical education equal objectivism and subjectivism equals technical ignorance?
This looks to me like a generalized, unproved, assumption.
Is it a fact? Based on what?
PMA said:
Good points, but could you elaborate on that 1 ohm+22R//20mH//500uF network, please?
Joshua_G said:
Joshua, did you not report yourself as an audio engineer a few posts back or on some other forum? Only now you ask what is FFT ????
alan, I believe he said "recording engineer".
nvm.
Anyhow, Pavel, I like looking at the shape of the distortion residue... and the reactive load tests... Joshua the FFT of the distortion residue will give us a response curve that shows the spectra of the distortion residue, assuming it is not merely broadband noise (and it usually is not).
But, I thought the question might have been about passive devices, like cables, caps and resistors? Not sure.
_-_-bear
nvm.
Anyhow, Pavel, I like looking at the shape of the distortion residue... and the reactive load tests... Joshua the FFT of the distortion residue will give us a response curve that shows the spectra of the distortion residue, assuming it is not merely broadband noise (and it usually is not).
But, I thought the question might have been about passive devices, like cables, caps and resistors? Not sure.
_-_-bear
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