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Old 3rd September 2009, 08:38 PM   #921
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Quote:
Originally Posted by Juergen Knoop View Post
who knows? Do you want 500kHz bandwith or not?
Wrong answer.

It is very good measurement for an audio amp, but incomplete. As soon as it is a single ended tube amp, the hardest measurement can be omitted.
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Old 3rd September 2009, 08:44 PM   #922
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Quote:
Originally Posted by Bob Cordell View Post

Secondly, if a lab experiment exposes such in-harmonic distortions, how does one conclude that they are a result of the PIM mechanism as opposed to something else?
My approach depends on what do I measure, and which weak point this thingy has. Then I figure out how to push the thingy into the directions that highlights symptoms of the weak point in question, like on the picture above I pushed up frequency of well visible sharp meander to observe phase behaviour.
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Old 4th September 2009, 03:34 AM   #923
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Just talked at length with Mitch Cotter about angular modulation, etc. I am still OK with my input on this subject. I recommend that everyone else 'crack a book' (Mitch's suggestion for all of you) if you don't want to fall off an intellectual cliff.
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Old 4th September 2009, 04:25 AM   #924
anatech is offline anatech  Canada
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Hi John,
Well, I see you are still long on talk and very shy on substance. In other words, no change in your personality at all. You really do like to get shots off in every direction, even though I haven't posted here for a bit and you saw fit to bring my name up.

All anyone has ever asked of you is to answer a question directly, and use your vast knowledge to explain the issue clearly. A simple request really.

Also, I'm not trying to knock you. You aspire to be something you are not, it's that simple. I have no problem being technical and not an engineer. Fragile ego there John?

I can see you on the ground of the base of said "intellectual cliff", right beside your moral abyss. Why not try a different approach? Try not to disrespect people around you for one. It doesn't reduce your importance to show good manners socially. In fact, you will probably see that social grace elevates a person's reputation.

I don't know John, your guidance here has the thread spinning it's wheels in a never ending donut. What a waste!

-Chris
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Old 4th September 2009, 04:53 AM   #925
GK is offline GK  Australia
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Quote:
Originally Posted by anatech View Post
In fact, you will probably see that social grace elevates a person's reputation.

Yup; even if they’re a complete dolt.
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Old 4th September 2009, 04:53 AM   #926
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Anatech, I really don't need this, and you, a moderator too.
The problem is with an intimate understanding of FM modulation, how it happens, what it looks like on a spectrum analyzer. I only have a partial understanding of this, so I am reluctant to 'teach' others about it. Yet, I have 'hit the books' and maybe the test equipment in future, to get a better understanding, so that I can even teach a wider audience, what we have found.















The 'smoking gun' is FIG. 3 of my Matti's and my AES paper on TIM. It is OBVIOUS from looking at the measurement, that there are extra distortion products that DO NOT REPRESENT what we would EXPECT from the test itself. Not knowing what they were, we just IGNORED them. After there was plenty of other distortion products in the same figure that showed what we were trying to measure and point out, at the time.
I have been shown that these are FM products, NOT IM products. How do we know? We know, because these products are NOT harmonically related to the test signal components and appear is completely unrelated to the test signal itself. Any engineer would get nervous over this, because that is not supposed to happen.
All I can ask of anyone or everyone, is to read up on IM distortion products, before telling me that I don't know what I am talking about. That is all I ask here.
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Old 4th September 2009, 05:55 AM   #927
iko is offline iko  Canada
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It's like driving by a highway accident, and I keep telling myself "don't look" but still I slow down and can't keep myself from looking.

Still, all attitude aside, it seems the guy with the eye on the ball at the moment is Mr. Curl.

Not that the opinion of a bystander would be important to you, but this is the interweb after all, so even bystanders can post. I see a lot of armchair speculation and pseudo-science. Sure, that's fine, but seeing how serious you guys are, I think John's right on the money proposing "hitting the books" and the hardware. I mean, are you discussing figure x from a 1976 paper? Papers are not like vintage wine necessarily. If nothing's been done in the area since then, I'd say it's about time that someone turn on that measuring thingy and do some real hands-on research. If a lot has been done in the area and you're not up to date, well, then that's not very good is it?

Apologies if the tone is perceived as inappropriate, that's not what's intended; but I've spent some years in research (like some of you, surely), and if indeed you guys have some good ideas, and there's nothing wrong with chatting, as long as something real comes out of it. And however much I found John's attitude (in the past in general) repulsive, I have to give him most credit at the moment, for pointing in what I think is entirely the right direction.
Regards.
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Old 4th September 2009, 06:18 AM   #928
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Thanks, IKO, even if you think of me as a repulsive guy. I am just trying to get audio designers up to date, and I have done so, without pay, and lots of derision, for several years. My business associates think me 'nuts' to do so, and they probably are right. I am working on several projects at the moment, why should I bother to teach people who might just use it against me, either with added knowledge gleaned from the discussion, or disparaging others to take me seriously, because I am so 'out there'?
At this time, I have 4 power amps that seem to work, and I get monthly royalties for. I am known for 2 preamps, one that started this thread, and another that is pretty good, at least, the audio mags think so.
I am working on 2 phono stages and one (very new) power amp at the moment, and a few other things. However, my business associates, some even more qualified than me, technically, would not give this thread the sweat off their brow, and that is why they don't jump in here. Perhaps they are right, and even Walt Jung doesn't bother to contribute, yet we have written a paper together and known each other for 35 years.
However, do you yet understand why they won't contribute here? ATTITUDE, and disrespect for major contributors to the audio art. I am only the messenger, just like the teacher trying to make progress at a tough high school, and failing for the most part.
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Old 4th September 2009, 06:33 AM   #929
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Quote:
By JC- ATTITUDE, and disrespect for major contributors to the audio art. I am only the messenger, just like the teacher trying to make progress at a tough high school, and failing for the most part.
Even through I dislike some of the "attitude" here , I still find you (I did group you in my "legend" subcategory of contributors ) very valuable as a source of historical and technical info worthy of further investigation (the internet).

Please do not give up , some of "us" take a while (like a new vintage).
OS
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Old 4th September 2009, 11:58 AM   #930
pooge is offline pooge  United States
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It is still: The three phases of an assertion.

1. "I've discovered a new phenomenon that makes me better."
2. Defend it by name dropping and using data obtained from an obsolete IC that probably doesn't apply to a competently applied design.
3. Avoid any further technical defense by attacking the intellegence, ethics, motivation, etc., of anyone who questions the phenomenon.

How about that everyone?


Looks like we're at Stage 3 again.
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