Bob Cordell Interview: BJT vs. MOSFET

PMA said:
He finds it advantageous, though high order harmonics he has are quite high!

And this is 1W. We often hear that first watt counts :D

Look at the favorite 7th harmonic, it is the highest!! John, how would it sound??

One of the things that is most annoying about this forum is the ignorance of the people that post here.

You all enjoy poking fun at anyone that doesn't do things the way you do, and you think you are so clever. But you are really just ignorant fools.

In the first place, you haven't the wits to realize that there is something wrong with the graphs you so gleefully posted. Supposedly, this is the spectral analysis of the output at 1 watt into 8 ohms:

407MXRFIG08.jpg


But how can you reconcile that with the distortion residue shown in an analog fashion? Even the fools that inhabit these forums should be able to tell that the distortion at 1 watt into 8 ohms consists virtually entirely of second harmonic and noise only:

407Mxrfig06.jpg


So clearly there has been an error of some kind made in the graphs posted on the Stereophile website. But I suppose it is too hard to actually think. It is easier just to mock.

In the meantime, I am laughing all the way to the bank. The MX-R just won an award from Hi-Fi Choice, it is about to win an award from Hi-Fi +, and it is due to receive another award from another major US magazine. These are all from people who actually bothered to listen to a product rather than mock it without the slightest experience with it or understanding of it.

Go ahead and enjoy listening to your high-feedback designs that measure oh-so-well on the test bench with steady-state signals into resistive loads. In the meantime, I am going to enjoy listening to some music on my zero-feedback system that is actually connected to a pair of loudspeakers ...

Edit: Oh, and I forgot the award it won last year from Stereo Sound magazine in Japan.
 
AX tech editor
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Charles Hansen said:


One of the things that is most annoying about this forum is the ignorance of the people that post here.

You all enjoy poking fun at anyone that doesn't do things the way you do, and you think you are so clever. But you are really just ignorant fools.

In the first place, you haven't the wits to realize that there is something wrong with the graphs you so gleefully posted. Supposedly, this is the spectral analysis of the output at 1 watt into 8 ohms:

407MXRFIG08.jpg


But how can you reconcile that with the distortion residue shown in an analog fashion? Even the fools that inhabit these forums should be able to tell that the distortion at 1 watt into 8 ohms consists virtually entirely of second harmonic and noise only:

407Mxrfig06.jpg


So clearly there has been an error of some kind made in the graphs posted on the Stereophile website. But I suppose it is too hard to actually think. It is easier just to mock.

In the meantime, I am laughing all the way to the bank. The MX-R just won an award from Hi-Fi Choice, it is about to win an award from Hi-Fi +, and it is due to receive another award from another major US magazine. These are all from people who actually bothered to listen to a product rather than mock it without the slightest experience with it or understanding of it.

Go ahead and enjoy listening to your high-feedback designs that measure oh-so-well on the test bench with steady-state signals into resistive loads. In the meantime, I am going to enjoy listening to some music on my zero-feedback system that is actually connected to a pair of loudspeakers ...

Edit: Oh, and I forgot the award it won last year from Stereo Sound magazine in Japan.


That's some interesting mental acrobatics Charles.

On the one hand you tell us not to believe everything Stereophile tells us, as they also make mistakes, as shown by you. And who's to say WHICH of the curves are wrong or right? Maybe none is correct? Yet the awards they give out are of course spot on.

BTW did you also tell those Stereophile people they are ignorant fools or is this honor reserved exclusively for people who can't harm you?

Jan Didden
 
x-pro said:
It would be useful to mention a note John Atkinson placed just above these graphs:

"(Note that the higher-order harmonics visible in these two graphs are almost certainly mathematical artifacts.)"

If John himself admits it there what all the fuss is about?!

Alex

Why do not these "almost certainly mathematical artifacts" do not appear with another really good amplifiers, like Halcro etc.? Simaudio ... ?

You are pulling our legs, but you do it to wrong people, who are qualified and experienced!! We are not any dumb commercial crowd!! And probably some of us are more qualified and experienced in EE than you, who call yourself experts!!
 
PMA said:


Why do not these "almost certainly mathematical artifacts" do not appear with another really good amplifiers, like Halcro etc.? Simaudio ... ?

You are pulling our legs, but you do it to wrong people, who are qualified and experienced!! We are not any dumb commercial crowd!! And probably some of us are more qualified and experienced in EE than you, who call yourself experts!!

Pavel,

I only quoted what John Atkinson said, and your questions and anger should be addressed to him, not to me. I pesonally don't understand why John did publish these graphs if he himself was not happy with these harmonics - I wouldn't. However you made loud noises about something that even the person who did the measurements is not sure about. I think it is not fair.

Cheers

Alex
 
Again, it is easier to mock than to think...
Perhaps I should charitably assume that the problem is ignorance about how the publication process works.
A listening review, which takes time to write and at least one or two revisions, then is line edited by at least one editor, follwed by galleys of the review (which are edited once again), is generally going to reflect a more-or-less accurate summation of that reviewer's impressions of a piece of equipment. You may or may not agree with that reviewer, but that's another matter.
A graph is not line edited. Nor is it likely to be doubted by anyone down the line. One wrong setting on the test equipment--worse yet a mislabeled graph--and it will still sail right through the publication process without revision. Have you never noticed the pattern in how scientific journals publish errata? It's nearly always about the labeling of a graph or the scales or the caption; rarely about the written content.
In any event, the intent of a magazine such as Stereophile is to listen. Measurements are of secondary interest. If they show something that might relate to what is heard, you might potentially learn something from that. Maybe. If the tests reveal nothing relating to the listening, then they are of academic interest, but not necessarily something you'd want to base your buying decision on. Note that the magazine is not simply a series of title pages followed by a half-dozen graphs and a couple of tables of numbers...they actually wrote down some words in an attempt to communicate. You're not listening (in any sense of the word), but that doesn't mean that they're not trying to talk to you.
FREE BUSINESS IDEA:
If you think that measurements are complete discriptors of the sound of a piece of equipment, start a magazine which only publishes numbers--no listening, whatsoever. You'll be extolling mid-fi, I suppose, but that's fine. You'll be happy, your readers will be happy, and you can all agonize over thousandths of a percent distortion until the end of time.

Grey
 
Jan and Pavel It appears that the higher order residual is in the oscillator or the fft. Get some experience with comparing the distortion WAVEFORM with the distortion FFT.
This would be an innocent question IF you were polite about it. However, you two CHOSE to attack Charles, rather than understand the situation.
John Atkinson should not have published this pair of 1KHz measurements, because they are misleading. They show higher order distortion, but it is NOT generated in the amp under measurement. This can be easily proved by comparing the two graphs and noting that the higher order distortions do NOT increase while the lower order harmonics DO increase. This is not realistic.
At low levels, UNLESS there is significant crossover distortion, we expect only 2'nd and 3'rd harmonics at any significant level. This is because higher order harmonics are almost impossible to be at any significant level in a class A or class A-B amp. It is a mathematical series that shows the change in the harmonics with level. Higher order harmonics just don't get generated to any degree, compared to lower order harmonics. Now if Charles has significant crossover distortion in his amp, then maybe, higher order harmonics could be generated by a dead zone caused by very low bias.
What is your bias Charles? That should answer that question.
 
AX tech editor
Joined 2002
Paid Member
john curl said:
Jan and Pavel It appears that the higher order residual is in the oscillator or the fft. Get some experience with comparing the distortion WAVEFORM with the distortion FFT.
This would be an innocent question IF you were polite about it. However, you two CHOSE to attack Charles, rather than understand the situation.
John Atkinson should not have published this pair of 1KHz measurements, because they are misleading. They show higher order distortion, but it is NOT generated in the amp under measurement. This can be easily proved by comparing the two graphs and noting that the higher order distortions do NOT increase while the lower order harmonics DO increase. This is not realistic.
At low levels, UNLESS there is significant crossover distortion, we expect only 2'nd and 3'rd harmonics at any significant level. This is because higher order harmonics are almost impossible to be at any significant level in a class A or class A-B amp. It is a mathematical series that shows the change in the harmonics with level. Higher order harmonics just don't get generated to any degree, compared to lower order harmonics. Now if Charles has significant crossover distortion in his amp, then maybe, higher order harmonics could be generated by a dead zone caused by very low bias.
What is your bias Charles? That should answer that question.


John,

You didn't get my point. I did not give any opinion on any curves. I resent to be called 'ignorant fools' by someone who accepts awards from an outfit that can't even get their own reports right, and then wants us to believe that when it gives out awards it's doing The Right Thing. Give me a break.

Jan Didden
 
Jan, I'm surprised at this post -- you are not usually this slow on the uptake.

janneman said:
And who's to say WHICH of the curves are wrong or right? Maybe none is correct?

Did it ever occur to you that I have a distortion analyzer? (I think I actually pointed that out earlier, either in this thread or the one linked below.) So of course I know which curves are correct.

janneman said:
BTW did you also tell those Stereophile people they are ignorant fools or is this honor reserved exclusively for people who can't harm you?

Did you miss the thread devoted to my letter to the editor of Stereophile? Try looking here if you did:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=109067

And if you still think I am bashful about pointing out errors made by Stereophile, try this link:

http://db.audioasylum.com/cgi/m.mpl?forum=critics&n=12318
 
Administrator
Joined 2004
Paid Member
Hi All,
I really think we should try to talk about things and not each other. When emotions run high, the messages get lost in the noise.

Another thing I can't help but notice. You are all accomplished in your fields, not one of you are stupid by any means. You are all due respect also.

So please, state an opinion as such and proven facts as they are. Don't try to read too much into comments and refrain from showing a lack of respect to your peers. I'm just a pip squeek among giants guys. Try not to squish me and others like me! ;)

Anyway, you don't have to like each other. You don't have to agree with each other. Let's try and keep things on a professional level. You never know who may read a thread here.

-Chris