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Old 25th January 2013, 01:54 PM   #33531
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Thanks, SY.
I believe we are several, here, to try to *understand* the numerous causes of audible distortions, in order to address them the correct way. Others ( 'audiophiles') are more interested in 'Tips'.
Tips can work in a situation, and be totally useless in an other. Cable's sound is a good example.
When we design some circuit, we have to know the all landscape, deeply, i mean, near instinctively. In order to ask ourself the good questions, and find the best solution at each step.
I understand how John, after so many years, can be tired of those concerns, means forget the curiosity and maths and use exclusively what he think 'works'. The aluminum case is a good example.
I can even understand why, because he need his reputation and strong positions for a living, reassuring for customers and commercial partners, he can be so abrupt and definitive.

Just one day, John, you will realize a DIYer forum is not the right place for such an attitude, reserved for audio shows or presentations of some products to the audience or mass media.
I just noticed your choices were near always good, even if the reasons you provided were not.

The good answer about electronic enclosures is to explain Eddie Currents effects, not 'I use aluminum cases'.

The good side of the things is that, reacting against this marketing attitude, some knowledgeable engineers, here, provide the good stuff in return. In a way us, stupid scientist oriented guys, can understand and correlate.

This thread is the one where i have found the most valuable and numerous inputs in the same place (with the use of a good noise-gate). Learned a lot of thinks here, or had a lot brought back to the surface, buried in my memory.
Thanks a lot at all, including John. Your passions are gifts.

And to John, even if i do not agree with you unconditionally, even if i tease you often, in reaction to your provocative attitude, i read your inputs with great interest and attention.
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Old 25th January 2013, 02:08 PM   #33532
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Originally Posted by kgrlee View Post
Thanks for this Pavel.

I should point out that 5532/4 essentially has C2 built into its compensation with the same beneficial effects on distortion, particularly high order stuff like JC's 7th. It's one reason why its performance still rivals the new uber OPAs in real life.

NO!!!
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Old 25th January 2013, 02:10 PM   #33533
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George,

Many years ago I had a consultant with me tuning a baseball field sound system. He was dictating the adjustments and I twiddled the knobs. Now one thing I picked up on was when he told me to make a filter deeper, he wasn't happy until I made it wider. Same thing when he said wider I gave him deeper. When we got to the tweeters nothing I did seemed to have any effect. I mentioned we should check things out. His response was that the correlation function showed good results, so we were limited by level, noise etc. After he left I checked and the tweeter amplifier racks indeed had no power. Now if you are charge $2,000 a day, apparently you don't have to be embarrassed.

For chuckles try:

http://www.analog.com/static/importe...als/MT-042.pdf
http://www.analog.com/static/importe...als/MT-043.pdf
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Old 25th January 2013, 02:16 PM   #33534
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Christophe, after new listening tests of the buffered AD797 I find this opamp very, or I would say extremely transparent, with great resolution of highs and details, and tight solid bass. In the past I have probably not implemented it well. I think you would like this part.
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Old 25th January 2013, 02:21 PM   #33535
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Originally Posted by jneutron View Post
Um, look up two posts.
jn
JN, yes I did and noted your explanation, and thank you.
In the case of the cd player concerned the lid was fully three inches+ above the main pcb, and the brick concerned was on top of the top chassis cover.
Considering the physical seperations and wall of RF noise produced internally, I find the effect most curious

Dan.
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Old 25th January 2013, 02:25 PM   #33536
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Originally Posted by Esperado View Post


The good answer about electronic enclosures is to explain Eddie Currents effects, not 'I use aluminum cases'.
This was repeatedly explained in this thread, or in the part I. So the DIYaudio search engine would help. Try to take another view - people might consider searching before they ask questions. It is time consuming and boring to reply same questions in circles and to give same answers. Problem of forums everywhere.
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Old 25th January 2013, 02:42 PM   #33537
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Originally Posted by PMA View Post
I think you would like this part.
Yes sir, sir. Ordered ! (Time to question my current-feedback dedication).
I still miss my 2 ideal OPAs.
Both fet inputs with >20KHz open loop bandwidth, with differential inputs, witch can be configured CFA or VFA, one low noise (<1nv with >50 V/µs slew rate ), one high level (<10nV, >500v/µs, IO>=100ma). Both unity gain stable.
I'm sure it could be done. there is always something i dislike, reading at the data sheets of available devices.
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Last edited by Esperado; 25th January 2013 at 02:44 PM.
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Old 25th January 2013, 03:23 PM   #33538
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Quote:
Originally Posted by simon7000 View Post
George,

Many years ago I had a consultant with me tuning a baseball field sound system. He was dictating the adjustments and I twiddled the knobs. Now one thing I picked up on was when he told me to make a filter deeper, he wasn't happy until I made it wider. Same thing when he said wider I gave him deeper. When we got to the tweeters nothing I did seemed to have any effect. I mentioned we should check things out. His response was that the correlation function showed good results, so we were limited by level, noise etc. After he left I checked and the tweeter amplifier racks indeed had no power.
So what your saying is...power cords make a difference even in a stadium.

jn
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Old 25th January 2013, 03:27 PM   #33539
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Originally Posted by Max Headroom View Post
Considering the physical seperations and wall of RF noise produced internally, I find the effect most curious .
Something related with mechanical vibrations damping generated by the CD rotation ? Number of corrected errors can change the sound quality a lot.
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Old 25th January 2013, 03:27 PM   #33540
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Well, maybe it is a good time to 'clear the air' a little bit.
First, I apologize if I come off as arrogant or overcritical. It is just the way that I communicate, and I have never learned 'diplomacy'. That does not mean that I am always right, or anything, but old habits are hard to change.
Please, just remember, some people who have smoothly modulated inputs, may in fact, be deceiving you for some reason or cause, and they can do it easier than I can, because they seem so sincere.
As far as I am concerned, I try to be as truthful and accurate as possible about audio history, and my ideas of how to make better audio designs. I have ALWAYS been truthful, but that does not mean that I am ALWAYS right. Sometimes, I can be found to be wrong, and while I can be embarrassed, just like anyone else at being in error, it doesn't mean that I was not well-intentioned in the first place. I would not waste my time to make up a 'story' about something. Let's leave that to the marketing departments of the various companies that I work with.
Much of what is said about my products on this thread recently is all 'smoke'. It has no basis in reality. Especially the input from that guy in OZ. It is laughable, to me, but many here might not be able to realize that it is a complete 'fantasy' on his part, so if you are in any doubt, do a little personal checking for yourself on the internet.
In any case, I DO believe that there is more to audio design than just static measurements. I have offered some alternatives like the Hirata test, and PIM, but they have limited usefulness, and don't tell us everything that our ears seem to perceive.
If you don't believe in what your ears tell you, then I can do little to help.
I am close to 71 years old, my associates are dying around me, two passed away just this last month. I just passed though a personal cancer scare, myself. I feel that I have limited time to give free advice, and I certainly don't have the energy to do extensive measurements, even with the lab equipment at my disposal, without some practical reason behind it. If I was 35 years old, well maybe then, but not now, so please don't ask me for the effort when you could probably do it, yourself.
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