Chris;
SSB was just an example of nasty additions to sounds that happen due to phase intermodulation.
Yes, resistors in feedback are more linear than what they surround, otherwise there would be no meaning in wasting them, as well as wasting gain lowering S/N ratio.
Linear things do not exist in reality. And there is no waist between high - end and SSB. That means, in order to understand what does exist in any high end gear you may gradually increase some non-linearities and their products until they are well visible on an oscilloscope and the character of their nastiness is well audible. Then you may go back decreasing them as much as possible. However, fighting against some distortions you may see how different kinds of them are created; now you can gradually increase them until you hear them, see them, and understand well how to produce them. When you know well how to produce them you know what to do to minimize them.
And so on...
SSB was just an example of nasty additions to sounds that happen due to phase intermodulation.
Yes, resistors in feedback are more linear than what they surround, otherwise there would be no meaning in wasting them, as well as wasting gain lowering S/N ratio.
Linear things do not exist in reality. And there is no waist between high - end and SSB. That means, in order to understand what does exist in any high end gear you may gradually increase some non-linearities and their products until they are well visible on an oscilloscope and the character of their nastiness is well audible. Then you may go back decreasing them as much as possible. However, fighting against some distortions you may see how different kinds of them are created; now you can gradually increase them until you hear them, see them, and understand well how to produce them. When you know well how to produce them you know what to do to minimize them.
And so on...
Hi John,
Is it not true that in video, the bandwidth is wide, but low noise is not an overriding concern? Video signals are normally 140 IRE (1 Vp-p) and low impedance (around 75 ohms). You will either have close to 140 IRE level, or nothing but noise, whereas audio signals exist throughout the entire range from uV to a few volts. In fact, the first 40 IRE (0.286 Vp-p) is blanked in video, swallowing up any noise from active stages. There is a very real risk that video op amps may generate avoidable noise. The newer audio op amps can have slew rates of 20 V/uS or greater. In fact, the LM318 from years ago had a slew rate to 50 V/uS and around 70 V/uS when feed forward compensation was used. Now, that just has to be fast enough. If not, we have op amps suitable for audio that cook along pretty fast. Of course, they run pretty warm and heat is the enemy of all that is electronic and quiet. Why go the route that promises a short life for expensive electronics when this is not required?
Politics? What politics? The only politics that seem to exist are from your anointed group of higher level beings (Dick Sequerra or Mitch Cotter and yourself)? The great unwashed (us) are not to be enlightened?
In fact, you seemed to disappear as soon as some focused questions were put to you. You have yet to answer any of them so far. I am really beginning to thing that you haven't got the foggiest notion yourself!
This is not a very professional way to behave John. 
from Anatoliy ...
John, for the sake of your reputation, and to go forward in the direction that you would like to go, you only have to respond directly to some questions that were put to you. Some of these were over a week ago, so you have had enough time to look the answers up. If you need some research time, just ask. I'm pretty sure everyone would accommodate you without a fuss.
Oh, and stop insulting us. It's not very pretty.
-Chris
So, this is your definition of "lowish" feedback then? Just getting the terms nailed down ...
Well, if you will accept my input.
Is it not true that in video, the bandwidth is wide, but low noise is not an overriding concern? Video signals are normally 140 IRE (1 Vp-p) and low impedance (around 75 ohms). You will either have close to 140 IRE level, or nothing but noise, whereas audio signals exist throughout the entire range from uV to a few volts. In fact, the first 40 IRE (0.286 Vp-p) is blanked in video, swallowing up any noise from active stages. There is a very real risk that video op amps may generate avoidable noise. The newer audio op amps can have slew rates of 20 V/uS or greater. In fact, the LM318 from years ago had a slew rate to 50 V/uS and around 70 V/uS when feed forward compensation was used. Now, that just has to be fast enough. If not, we have op amps suitable for audio that cook along pretty fast. Of course, they run pretty warm and heat is the enemy of all that is electronic and quiet. Why go the route that promises a short life for expensive electronics when this is not required?
What is wrong with some way of defining performance? If everything is subjective, there is no way to prove or disprove anything. A safe place for some people to be.
To take up research on anything, one needs a direction to take. You have refused to provide much of any information thus far. Not anything proved at any rate. Your failure to answer questions directly has directly contributed confusion (as we forget the questions you were to answer).
Politics? What politics? The only politics that seem to exist are from your anointed group of higher level beings (Dick Sequerra or Mitch Cotter and yourself)? The great unwashed (us) are not to be enlightened?
In fact, you seemed to disappear as soon as some focused questions were put to you. You have yet to answer any of them so far. I am really beginning to thing that you haven't got the foggiest notion yourself!
I realize this is aimed at Scott, and we have no clue what has been said or is going on between you all. Still, this is rude, just like whispering a secret. If everyone is a colleague, then you know each other well enough to call "after hours". In fact, it appears as though you are trying to discredit Scott in front of other people by implying he is dead wrong and his group will kindly and gently explain the error of his ways.
This is not a very professional way to behave John. Okay, I bite. Produce the paper so we may all read it please. If you can't/won't, is there anyone else who can help us out here?
My word John! That's just plain rude and insensitive. It goes to you attempting to discredit Scott I think. Subjective opinion of course!
Weren't you taught any manners when you were growing up John? You are being rude again. Let's explain how things go here John. You make the claim, so you are the one who is expected to explain or prove your claim. Do you understand how this works now? The concept is pretty simple really. That is why you are asked questions, as a hint that you haven't properly explained yourself.
Now you are insulting Anatoliy, historically you enjoy talking about microphones. Are you the only one who can talk about microphones?
from Anatoliy ...
I'd say that Anatoliy has hit the nail directly on the head there John. I completely agree with him.
And now you have figured out a new way to insult a group of people! Since Dick Sequerra does not post here, how are we to know that he reads this forum and the opinion is actually his? After all, you could be filtering the information from here. But, you are right about one thing, watching you run around in circles is a complete waste of everyone's time. After all, the only thing you have attempted to "teach" us is that you are brilliant and your knowledge is too vast for us to grasp. I would like to think that Dick Sequerra has far better social skills than you seem to possess.
John, for the sake of your reputation, and to go forward in the direction that you would like to go, you only have to respond directly to some questions that were put to you. Some of these were over a week ago, so you have had enough time to look the answers up. If you need some research time, just ask. I'm pretty sure everyone would accommodate you without a fuss.
Oh, and stop insulting us. It's not very pretty.
-Chris
Hi Anatoliy,
Yes, I figured that was the case. But now I think we are splitting hairs. Resistors do have some voltage and heat dependence, but the amount isn't that significant and easily kept to unimportant levels.
We are in agreement with this, and what differs is the matter of degree these things represent.
-Chris
Yes, I figured that was the case. But now I think we are splitting hairs. Resistors do have some voltage and heat dependence, but the amount isn't that significant and easily kept to unimportant levels.
I'm not fighting you on this. It's a matter of degree, and this is not something engineers or technicians are taught in university. Well, at least not when I went, even in the audio study groups of that time. The fact that we are looking into these things now reflects a large advance in what we understand audio to be. After all, I consider audio to extend up to about 1 MHz and beyond if a circuit is misbehaving. That also represents a leap of understanding since we were taught that audio extended to a couple hundred kilohertz. Even that was under debate back then.
We are in agreement with this, and what differs is the matter of degree these things represent.
-Chris
Hi John,
I'll be staying at the Denver Marriott Tech Center. Flying in Friday morning, flying out Sunday evening.
Cheers,
Bob
John;
we are going in circles because you keep ignoring what people are saying right on target, and the single thing we can learn from you is how to avoid direct answers referring in circles to something out of the scope of the discussion. I.e. how to contribute to prolonging the discussion without adding any meaning to it's content.
You Ukrainian snake oil merchand, have you missed this?
http://www.diyhifi.org/forums/viewtopic.php?p=40686#p40686
And if there's any doubt about the need and reasoning beyond this endless and useless discussion, here's the explanation. Three legs good, eight legs bad:
http://www.diyhifi.org/forums/viewtopic.php?p=40705#p40705
I'm ready to match Scott's donation if anybody can proof beyond any doubt the production of totally inharmonicaly related frequencies from a simple op-amp circuit, from uA709 to THS4275.
Anybody with some math skills can read the Fourier theorem. Bottom line, each and every periodic f(x) that is "sectionally smooth" over a period (like −PI < x < PI), that is, continuous and differentiable there except possibly at a finite number of finite jump discontinuities, has a unique harmonic representation, as an infinite sum of linear combination of sin(n*x) and cos(m*x). Linear, nonlinear, FM, PM, AM, TIM, PIM, KIM, ZIM, DFGRTHM, G-J-H-Y-F-M, it doesn't matter, the same theorem and result applies.
Now, if we agree that every signal "x" that we can ever get in the real world matches the above requirement, what's left is denying the theorem itself. That wouldn't be surprising from somebody who, earlier this year, went on a collision course with the second principle of thermodynamics and Shannon's theorems, for the sake of his good friend and associate Jack Bybee's business.
Otherwise, I'm sure JC is a very nice and respectable private person.
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That means, I am lucky, and nobody taught me as if some absolutely linear devices exist. We learned properties of devices, materials, including physics and chemistry involved, and from the beginning were taught to optimize design by many parameters searching for optimal solutions. There was even a very popular joke: a really big lady come to a dress designer, after measuring her around many times he asked, "Madam, where do you want me to make a waist on your dress"?
That means, in electronics design waist does not exist, it has to be specified by those who order the design.
There were so called classes in Russia for which different waists were specified. The gear which parameters fall in between some limits was classified as an "Equipment of a certain class". The equipment which parameters superseded class 1 boundaries were called "Highest Class", officially, and "Hi-Fi" unofficially.
The majority of our professors were teaching part time; their main jobs were either in scientific institutes, or in a real manufacturing; it was the second advantage.
Well, I just make amps and preamps for a living, and I am trying to pass what I think is important to others, as I pass into retirement. Unfortunately, retirement now seems farther away than I thought it would be, and I have to keep designing circuits. Maybe, it is a blessing. However, I will continue on my way in the direction that seems to work for me, and the rest of you can go yours. Isn't that fair enough?
However, no insult or rudeness intended in my previous inputs, especially today, but it doesn't seem to be what people read into it.
Scott, please go to Asia, God Speed, and good luck. No use bothering yourself with my suggestion.
Everyone else, please forgive my intrusion on this thread, even though it has my name associated with it.
However, no insult or rudeness intended in my previous inputs, especially today, but it doesn't seem to be what people read into it.
Scott, please go to Asia, God Speed, and good luck. No use bothering yourself with my suggestion.
Everyone else, please forgive my intrusion on this thread, even though it has my name associated with it.
Hi Syn08;
why referring to some Ukrainian snake oil merchand you quoted a posting of Russian "Designer and Technologist of Radio and Electronics Equipment?
Is it kind of a joke, or a sad mistake?
Hi John,
When someone attempts to pass knowledge or skill to the younger people "coming up", it helps to actually tell them something. To dance around the reasons why doesn't help anyone at all, not even you. Do you know what I discovered many years ago? I found out early on that the best way to really know a subject is to teach it. Being able to get the idea across to other people is very helpful to you. Luckily for me, I was in my late teens when I figured that out. Teaching is still something I enjoy doing. Why not give it a try? There is no better feeling as the one you get watching the lights come on in someone else's head as they grasp a concept. You are actually turning away what could be the best time of your life, and a very positive attribute that opens doors for you.
As I've said before, the two things you need to do is treat people around you with more respect, and answer questions directly. Everything else in your life will begin to fall into place once you begin doing those two simple things.
I really wish you well in the future, as I have in the past. But you do tick me off when you skirt a simple answer or put people down for no reason. What makes this doubly sad is that you aren't hurting anyone here by the way you interact with everyone, you are only hurting yourself. The one thing you do to us is disappoint some members and waste other people's time with the game.
I guess you'll laugh this up with your buddies next. Oh well ...
-Chris
When someone attempts to pass knowledge or skill to the younger people "coming up", it helps to actually tell them something. To dance around the reasons why doesn't help anyone at all, not even you. Do you know what I discovered many years ago? I found out early on that the best way to really know a subject is to teach it. Being able to get the idea across to other people is very helpful to you. Luckily for me, I was in my late teens when I figured that out. Teaching is still something I enjoy doing. Why not give it a try? There is no better feeling as the one you get watching the lights come on in someone else's head as they grasp a concept. You are actually turning away what could be the best time of your life, and a very positive attribute that opens doors for you.
As I've said before, the two things you need to do is treat people around you with more respect, and answer questions directly. Everything else in your life will begin to fall into place once you begin doing those two simple things.
I really wish you well in the future, as I have in the past. But you do tick me off when you skirt a simple answer or put people down for no reason. What makes this doubly sad is that you aren't hurting anyone here by the way you interact with everyone, you are only hurting yourself. The one thing you do to us is disappoint some members and waste other people's time with the game.
I guess you'll laugh this up with your buddies next. Oh well ...
-Chris
Math is a good thing to learn in order to become an engineer. It is not just because it is useful in making circuits, but the concepts that the math models, become second nature to engineers and physicists.
Without this background, much of what I wish to convey here, is lost. Not because I want it to be lost, but I just can't do the lower division math as well as well as convey the 'answers' without teaching a course, and this is not the place to do it.
Without this background, much of what I wish to convey here, is lost. Not because I want it to be lost, but I just can't do the lower division math as well as well as convey the 'answers' without teaching a course, and this is not the place to do it.
Hi John,
Then, explain best you can. Refer to papers where possible so that we can read them if we desire. A person who will not read can not be helped. Include the math where required in order to get your point across.
For all the talk and dancing, this could have been done already.
One last thing to consider. There are people viewing this thread that will jump in to help explain the math.
-Chris
Then, explain best you can. Refer to papers where possible so that we can read them if we desire. A person who will not read can not be helped. Include the math where required in order to get your point across.
For all the talk and dancing, this could have been done already.
One last thing to consider. There are people viewing this thread that will jump in to help explain the math.
-Chris
Most probably I'm too dumb to understand such jokes...
But I can give you a pleasure to show me harmonic relations between residue after nulling out a snare sound distortions by an opamp of your preference.
The problem is not in "Related are they or not", the problem is that intermodulations between say a flute and a snare can't be heard as harmonics of one of the instruments.
The same way, looking at John's picture nobody can tell, are "pimps" products of AM or PM.
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The IM paper I was referring to earlier is: 'Intermodulation Distortion in Tape Recording' Robert Z. Langevin JAES July 1963 Vol. 11, No. 2
"And it still appears that the best instrument for making this distortion-noise compromise is the trained ear. Acknowledgements: to Les Paul for being the best IM distortion analyzer in the industry today." (insider joke)
"And it still appears that the best instrument for making this distortion-noise compromise is the trained ear. Acknowledgements: to Les Paul for being the best IM distortion analyzer in the industry today." (insider joke)
John:
I received the PCB's today. I'll try to get one to you shortly.
------
What I have are some simple PCB's of a single opamp amplifying stage with "not" exceptional power supply bypassing. These were created for a measurement project not related to this issue. John wanted one so he could recreate the tests and confirm what happens/doesn't happen.
This whole issue has become pretty abstract. It started with a claim (fm modulation in op-amps) and a reference to some artifacts in a measurement that were not explained when the measurement was made. And then the low frequency open loop breakpoint of an op amp and its potential to cause the problem became the focus of the discussion. I believe a clear description of the issue is needed. Possibly a description of a possible test for the phenomena that can be reproduced would be very helpful.
John doesn't have the best people skills but he has a lot of experience to share and some novel ideas that we may all learn from. The trick is to get clarity of the core ideas and test them.
I think its entirely possible that there are other artifacts in the output of an op-amp, that they may or may not be harmonically related (which seems to get pretty complex fast*) and that they may be sonicly objectionable. I would divide the task a little differently (being more of an experimentalist). First try to find the simplest way to exercise an op-amp to generate the "artifacts". Find the simplest waveform that will make it misbehave in this way. Then see if it is unique to the op-amp in question or present in various degrees in other amplifiers. Then start the process of figuring out the cause. This is more difficult when the analytical equipment is full of the same potentially error producing devices.
Unfortunately there is a subjective element to this which makes it much harder. Despite years of research we don't have a definitive model for hearing that can tell us that 64K mp3's sound bad on classical music but are just fine on hip-hop. Or which harmonics are are not objectionable at low levels and which are highly annoying. We have a collection of disconnected rules that don't always apply. This makes the relative importance of a spurious output in a circuit an issue before we even address fixing it.
*Given our focus on mathematics I'm puzzled that the non-harmonic tuning of a piano has not been touched on. http://en.wikipedia.org/wiki/Piano_tuning#Stretched_octaves. Perhaps just being harmonic is the problem.
I received the PCB's today. I'll try to get one to you shortly.
------
What I have are some simple PCB's of a single opamp amplifying stage with "not" exceptional power supply bypassing. These were created for a measurement project not related to this issue. John wanted one so he could recreate the tests and confirm what happens/doesn't happen.
This whole issue has become pretty abstract. It started with a claim (fm modulation in op-amps) and a reference to some artifacts in a measurement that were not explained when the measurement was made. And then the low frequency open loop breakpoint of an op amp and its potential to cause the problem became the focus of the discussion. I believe a clear description of the issue is needed. Possibly a description of a possible test for the phenomena that can be reproduced would be very helpful.
John doesn't have the best people skills but he has a lot of experience to share and some novel ideas that we may all learn from. The trick is to get clarity of the core ideas and test them.
I think its entirely possible that there are other artifacts in the output of an op-amp, that they may or may not be harmonically related (which seems to get pretty complex fast*) and that they may be sonicly objectionable. I would divide the task a little differently (being more of an experimentalist). First try to find the simplest way to exercise an op-amp to generate the "artifacts". Find the simplest waveform that will make it misbehave in this way. Then see if it is unique to the op-amp in question or present in various degrees in other amplifiers. Then start the process of figuring out the cause. This is more difficult when the analytical equipment is full of the same potentially error producing devices.
Unfortunately there is a subjective element to this which makes it much harder. Despite years of research we don't have a definitive model for hearing that can tell us that 64K mp3's sound bad on classical music but are just fine on hip-hop. Or which harmonics are are not objectionable at low levels and which are highly annoying. We have a collection of disconnected rules that don't always apply. This makes the relative importance of a spurious output in a circuit an issue before we even address fixing it.
*Given our focus on mathematics I'm puzzled that the non-harmonic tuning of a piano has not been touched on. http://en.wikipedia.org/wiki/Piano_tuning#Stretched_octaves. Perhaps just being harmonic is the problem.
The joke is precise: human perceptions is the best instrument to find correlations, even some "Voices from Another World" were found in tape noises such a way.
http://www.altereddimensions.net/ghosts/EVP.aspx
For about 2 months I have been testing a preamp with 40dB FB, OLB 10kHz. JFET complementary-differential input stage, MOSFET output stage (not a diamond buffer). The listening test results are excellent, it has outperformed a BJT based preamp of similar topology by a class difference (in clarity, imaging, space, naturalness), and it has also outperformed OPA827 + discrete output buffer design; not mentioning another commercial products.
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