An amplifier with a LOW open loop bandwidth would have a 10 times greater difference between 1K and 10KHz or more. That is the difference. Of course, stressing 4MHz devices with 10K, class AB operation is not easy for the amp to do. Today we could do even better, BECAUSE we have better output devices.
It is, but if you look at the NAD M2 that is a lot worse and that has won a whole slew of accolades. The Pass XA60.5 Pass Labs XA60.5 monoblock power amplifier Measurements | Stereophile.com should be horrid according to the flatTHD brigade but is rated up with the JC-1 in class A components. I think either would happily suit me if I were in the market for a new power amp.
Of course, Nelson Pass is in the recommended components section as well. However, he is NOT coming on this thread and telling me that I don't know what makes a good audio amp. We have known each other for almost 40 years, and we respect each other. I don't go out of my way to give him a hard time, either.
Ya but you and everyone else who actually listens (including me) are a bunch of idiots that consume placebos all day long gleefully believing what ever is sold to us... so who cares?
Then please don't peddle the random experimenting within a group of believers as technical fact.
Those who can do . Those think they can make snarky comments upsetting those who can do . I have followed what John Curl has done since the ML days. The proof is in the pudding as it is said.
So do not get too upset when the monkey throw the only thing they do well at you . Regards😕
Everybody has beliefs, and nobody is unbiased. It's part of being human, and a function of how brains work. We can at least try to be civil with each other though. I hope JC will lighten up on the bragging type of posts, and others will try to keep things from escalating too much on their part.
Best to let it be. Kirchhoff's law or conservation of charge is not something you politely disagree about and discuss.
Yes, I'm preparing a challenge unfortunately it will entail a commitment to do a real DBT you know you really don't know style. Too much to lose?
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Okay. But, Kirchhoff's law is a simplified case of Maxwell's, so a discussion about when it is close enough may be subject to opinion. Conservation of charge is a more fundamental principle.
In any case, I think we could agree it would be inappropriate to get into a fistfight over either Kirchhoff or Maxwell, so it is a question of degree. That being the case, we don't have to be uncivil, and it's probably not productive anyway. Things just tend to escalate and each side starts to see the other side as evil. No need for that, if just we act like we would like other people to act towards us.
Ummmm... no. Kirchhoff theorems are direct corollaries of the charge conservation and energy conservation principles. Couldn't get closer to the first principles than this.
The only "approximation" is the assumption that the wavelength of the electromagnetic radiation is much larger than the circuit size. But the same applies to all electrokinetic as we know it, including the Ohm law. Otherwise, we got differential formulations, effectively local versions of the global theorems. Telegrapher's differential equations are the most common example.
no subjective claim - all decideable within EE
of course John is likely hiding a whole farming county's worth of strawman assumptions in " all things being equal"
while I have had to repeatedly point out that the "tricks" that let you get around his assumptions are 40+ year old EE textbook fare https://ocw.mit.edu/resources/res-6-010-electronic-feedback-systems-spring-2013/textbook/ specifically Roberge' 2-pole exposition in the final "Compensation Revisited" chapter
with several independent analysis published in the AES
theory, Audio Amp and custom Phase IMD measurement hardware comparable to Qaun's are in Cordell's early 1980's Mosfet Power Amp with Error Correction papers and references
need I summarize John's following totally nontechnical responses, deconstruct his deflections?
I didn't make a single audibility claim - or insist on DBT
this is all settled EE as taught in accredited University programs for decades, knowledge generally applied by thousands of EE in and beyond “Audio” applications
of course John is likely hiding a whole farming county's worth of strawman assumptions in " all things being equal"
while I have had to repeatedly point out that the "tricks" that let you get around his assumptions are 40+ year old EE textbook fare https://ocw.mit.edu/resources/res-6-010-electronic-feedback-systems-spring-2013/textbook/ specifically Roberge' 2-pole exposition in the final "Compensation Revisited" chapter
with several independent analysis published in the AES
theory, Audio Amp and custom Phase IMD measurement hardware comparable to Qaun's are in Cordell's early 1980's Mosfet Power Amp with Error Correction papers and references
need I summarize John's following totally nontechnical responses, deconstruct his deflections?
I didn't make a single audibility claim - or insist on DBT
this is all settled EE as taught in accredited University programs for decades, knowledge generally applied by thousands of EE in and beyond “Audio” applications
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You know, it has been 40 years since we (Matti and I) published a definitive article on TIM. Even then, we knew there was more, and exactly 40 years ago I was back in Finland starting new research on what was beyond TIM measurement itself. I didn't get very far, but Matti kept insisting on high open loop bandwidth as being subjectively important, even though amps 'could' be made with relatively high slew rates with a relatively low open loop bandwidth as well.
This was when Matti suggested 'differential phase distortion' a normal video problem, could be the answer. We went our separate ways, both of us making high slew rate power amps for our respective customers, and we both wrote and gave a few other papers for the IEEE and the AES, until around 1980 when Matti wrote about PIM with the mathematical foundation shown and suggestions on how to perhaps measure it. It wound up being more difficult to measure accurately, and only recently, Ron Quan finally really nailed it down.
However, back in 1980, the AES refused to publish Matti's PIM paper due to a Lipshitz et al censorship blockade, and then some real attacks on all of us by Bob Cordell who was trying to make a name for himself, and he had it personally in for Otala. He told me that himself. This crisis caused Matti, Walt Jung, Marshall Leach, and me to write a 15 page rebuttal to Bob Cordell in order to keep the TIM story straight, but Bob went off to test for PIM and he got ambiguous results, so he rejected it being important, much like he had tried to do to TIM, previously. The matter was not overtly pursued for about 15 years, we each going off to do our jobs and projects. Then the basic theory of PIM was brought up in an article by Barrie Gilbert in one of the electronic engineering magazines and research had been going steadily forward, mostly done by Ron Quan these days. Now, you can ignore progress, but it is difficult to ignore what sounds good and what just sounds fair, even if the specs look mostly the same. This is where we stand today.
This was when Matti suggested 'differential phase distortion' a normal video problem, could be the answer. We went our separate ways, both of us making high slew rate power amps for our respective customers, and we both wrote and gave a few other papers for the IEEE and the AES, until around 1980 when Matti wrote about PIM with the mathematical foundation shown and suggestions on how to perhaps measure it. It wound up being more difficult to measure accurately, and only recently, Ron Quan finally really nailed it down.
However, back in 1980, the AES refused to publish Matti's PIM paper due to a Lipshitz et al censorship blockade, and then some real attacks on all of us by Bob Cordell who was trying to make a name for himself, and he had it personally in for Otala. He told me that himself. This crisis caused Matti, Walt Jung, Marshall Leach, and me to write a 15 page rebuttal to Bob Cordell in order to keep the TIM story straight, but Bob went off to test for PIM and he got ambiguous results, so he rejected it being important, much like he had tried to do to TIM, previously. The matter was not overtly pursued for about 15 years, we each going off to do our jobs and projects. Then the basic theory of PIM was brought up in an article by Barrie Gilbert in one of the electronic engineering magazines and research had been going steadily forward, mostly done by Ron Quan these days. Now, you can ignore progress, but it is difficult to ignore what sounds good and what just sounds fair, even if the specs look mostly the same. This is where we stand today.
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that's very shakey ground, world class irony "Now, you can ignore progress..."
http://www.diyaudio.com/forums/lounge/200865-sound-quality-vs-measurements-493.html#post3007773
http://www.diyaudio.com/forums/lounge/200865-sound-quality-vs-measurements-493.html#post3007773
Thank you for the thoughtful reply. I see you point, but I think others may prefer a different perspective.
My views are in keeping with what is already well stated here: https://piazza-resources.s3.amazona...950478&Signature=0uFn6+V2cK5psESrr80J6R4zrhQ=
So far as I am aware, this is pretty much representative of what is usually taught in engineering schools.
EDIT: Just for anyone reading along, I would also like to respectfully disagree with Scott about wavelength being the only issue with approximation. To me, circuit layout is part of the end circuit, and stray coupling exists and can cause problems even when the frequency low. With respect to what happens with fields around wires and components at any frequency, Maxwell applies accurately in all cases.
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Hi George, it does not seem so 😀. Boulder is probably forbidden here, for some reason 😀.
I do not understand why - it is big enough, powerful enough, expensive enough, awarded enough, reviewed well, milled from single piece, up to 120 power transistors per amplifier - what's wrong? 😉
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