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Old 11th October 2010, 03:25 AM   #6121
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I wouldn't even be so strict as John is being. Sure it would be nice if you had a dozen or so different designs available for independent evaluation. But I would be just as satisfied if you had built a dozen or so designs, some with feedback and some without and listened for yourself if you noticed any sort of trend as to sonic differences between the two.

Then at least you would have an informed opinion. But at this point you are just some guy posting on the internet. That doesn't mean you're wrong. But it also doesn't mean that you're right.
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Old 11th October 2010, 04:18 AM   #6122
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Originally Posted by john curl View Post
As an engineer, Abrax... what kind of engineer are you?
A semi-retired one. I'm not employed by any consumer or professional electronics company at the moment. Just a hobbyist with a passion for pleasant sound.

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How many audio amps and preamps have you designed and are available for independent evaluation?
If you count all the amps I've designed I think none are in production at present, as I left the audio business in 2001. This means whether or not they're available for independent evaluation is debatable. But sure, if you want product names and approximate dates for their introduction I can supply them to you in a PM - I don't want to clog up your thread with irrelevancies. Just let me know (by PM).

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I think this is a fair question, as you infer that we are not engineers, and therefore are somehow flawed in our reasoning.
That's an example of flawed reasoning in itself. To me whether or not a person is an engineer is merely syntactics, irrelevant. Both your and Charles reasoning is flawed in various places but that has no bearing on whether you're engineers. In my book, if you say you are, then I accept you are. Being an engineer is no immunity against unreasonable arguments I hasten to add.

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Of course, MY definition of 'engineer' might be different than yours.
Indeed, I agree. So that's one reason why its irrelevant. Why introduce it?

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Does a piece of paper saying 'Engineer' make you an expert in this specific area?
Of course not, did you for one moment consider that it did?
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Old 11th October 2010, 04:25 AM   #6123
Variac is offline Variac  United States
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OK , I think everyone has made his point here, at least once.
The point isn't to have an argument, or to win one..
Move on to a different topic...

Last edited by Variac; 11th October 2010 at 04:36 AM.
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Old 11th October 2010, 05:17 AM   #6124
pooge is offline pooge  United States
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Originally Posted by Charles Hansen View Post
Self and the distortion analyzers have all the answers.
Yea. Who needs Self when you have all the answers.
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Old 11th October 2010, 05:29 AM   #6125
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Hi John,
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Oh, there is plenty of evidence, it is just buried by the op amp enthusiasts. ;-)
I have attached a file, data sheet actually, from New Japan Radio Company that should look a bit familiar to you. It seems that you are now an op amp enthusiast! The horror!

This may be the best way to satisfy the matching requirements inherent in your design. I wonder if they will come out with a similar design with a J-FET front end?

Are you an electronics engineer? This has been investigated earlier in time. Nope, you ain't. The definition is pretty clear on that count. Why is this so important to you?

Hi Charles,
Quote:
Self and the distortion analyzers have all the answers.
I don't think you have to knock the guy, he doesn't knock you. You disagree with his approach and he with yours. It's that simple. No biggie.

I guess I have a question for you though, if I may? How much measuring do you do while designing a circuit? I can understand that you don't design to satisfy measured specifications, nothing wrong with that. I can also accept that you've designed enough circuitry so that you know know what works and what doesn't. Your need for measurements has dropped as your familiarity with audio circuits increased in other words, but I would find it odd if you didn't use some equipment to actually see what your designs are doing.

My take on what makes a good designer is someone who accepts information from many sources, including the use of test equipment. So using accepted tests for audio design doesn't mean that you have to go in the direction of lower numbers for their sake. In your case, it's obvious that you aren't interested in the common pursuit of lowest THD (for example), but just how much attention do you pay to these various tests?

-Chris
Attached Files
File Type: pdf NJM2116.pdf (132.3 KB, 79 views)
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Old 11th October 2010, 05:31 AM   #6126
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Actually, Charles Hansen has a lot of the 'answers'. After all his products are world class in their acceptance by the sophisticated audio community, you know, the rich guys, who find audio quality to be one of their obsessions. I have a few in my 'camp' too. It takes more than some standard measurements to get this sort of acceptance. Charles and I feel that we are on the 'right track' in audio design. Your opinion may differ.
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Old 11th October 2010, 05:38 AM   #6127
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Anatech, I have perhaps $50,000 worth of test equipment if it was purchased new. I can measure to -120dB pretty easily with the addition of noise averaging, and I can measure this out to 100KHz in harmonics. Charles Hansen has even better equipment than I do, even though it is surprisingly similar. To imply that we don't measure our designs is just not part of the real world.
I'm glad to see that my 1968 design has finally made it to a new IC. It took long enough.
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Old 11th October 2010, 06:02 AM   #6128
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Quote:
Originally Posted by john curl View Post
I'm glad to see that my 1968 design has finally made it to a new IC. It took long enough.
Phase margin of 25 degrees John? Then its no wonder you have a disliking for feedback
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Old 11th October 2010, 06:08 AM   #6129
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Just the complementary differential part, I will take some credit for.
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Old 11th October 2010, 06:21 AM   #6130
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Abrax... I use plenty of feedback, just not as much as some op amp designers. Look at my Parasound JC-1 and JC-2 products. They have been measured in 'Stereophile' for all to see. The Parasound JC-3 will soon be introduced, and it is ALL IC op amps. It is the best that I can do, given what I have to work with. I would prefer a higher open loop bandwidth in my op amps, but the video amps are too noisy for MC input. A pity, as they sound pretty good. For the record, both Charles Hansen and I have degrees in Physics rather than Engineering, and I think this is the ONLY fact that we can be criticized for. However, I went back to university 4 years after finishing, in order to take the undergraduate and graduate analog design courses that I missed when getting my physics degree. I don't feel that I missed out on much.
Looking up your record, apparently you have designed some audio products. I hope that you will also allow that we have designed a number of successful products ourselves, and we continue in the direction that we feel works for us.
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