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Old 13th January 2012, 12:17 PM   #931
gk7 is offline gk7
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Quote:
Originally Posted by vanderpol4 View Post
Has anybody tried this test by Nelson Pass on a PP tube amp? Perhaps a way to measure/ monitor tweaks of the Global feedback loop?
Do you have a larger scan or a link to this article ? Itīs hard to understand with this small section what exactly is the procedure.
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Old 13th January 2012, 12:32 PM   #932
GloBug is offline GloBug  Canada
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Originally Posted by abraxalito View Post
Thorsten's 4 questions:

1) Not possible to tell with the information given. 'Near to perfect' to me means 'near to perfectly transparent' not 'near to perfect traditional measurements'.

2) No known set of measurements approaches unity correlation with transparency. For suggestions about getting closer see my earlier posting on this thread.

3) Most certainly not - the AP2 only tests in diff mode, not common-mode. (Note to Jan - not thinking CMRR setting on AP2 here ok?)

4) I doubt it very much. But presumably a cloth-eared set of potential customers could be pre-selected to achieve that result if desired.
Why not? you believe in God.....
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Old 13th January 2012, 12:34 PM   #933
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Sorry, can't understand which of my responses your question is directed at. Care to be more specific?
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Old 13th January 2012, 12:49 PM   #934
GloBug is offline GloBug  Canada
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This thread is starting to reminds me of my days learning Science in a Catholic school.

ie: Religious people always seem to have an answer, that fit's their agenda that is.
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Old 13th January 2012, 01:00 PM   #935
SY is offline SY  United States
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Let's keep away from religion in this thread, OK?
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Old 13th January 2012, 01:00 PM   #936
DF96 is offline DF96  England
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And irreligious people don't have answers to anything? Why should it be surprising if peoples' thoughts and opinions relate to their world view? We see it on here with audio debates: people starting from different positions often tend to end up in different positions, even though they all sincerely believe they are merely following the clear evidence set before them.

PS Oops, sorry, mod - delet this post if you like.

Last edited by DF96; 13th January 2012 at 01:01 PM. Reason: add PS
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Old 13th January 2012, 01:05 PM   #937
Pano is offline Pano  United States
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Originally Posted by ThorstenL View Post
I find this disappointing, as we have enough people here who normally have no problem to express their opinions and positions on what has been distilled into these four questions.
You've gotten a very clear answer in the lack of answers. What's hard to understand about that?
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Old 13th January 2012, 01:29 PM   #938
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Originally Posted by SY View Post
Let's keep away from religion in this thread, OK?
Nelson Pass's branch as well?
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Old 13th January 2012, 01:52 PM   #939
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Quote:
Originally Posted by ThorstenL View Post
1) With the AP2 Measurements as given above, do you consider this DUT to be "as near to perfect as possible"?

2) Do you feel any measurements not listed above, that is other than noise, harmonic distortion, intermodulation distortion, frequency response and load tolerance (damping factor); are required to make the determination in Question 1 and if yes, what are they?

3) Do the AP2 Measurements as given above inform us about about the actual performance of this amplifier when inserted into a real audio system?

4) Do the AP2 Measurements as given above inform us if the DUT when inserted into a HiFi Audio System will produce what is perceived by the majority of the potential customers "good sound" and would lead to a purchase of the DUT?

Ciao T
Thorsten,

Well given that a lot of "white box" testing went in to the development in order to achieve such extraordinary "black box" goals, and assuming that these additional tests included stability and clipping behavior. And that the Amp was within a reasonable dynamic power level, then:

1) Very likely yes, especially since I can perform any AP2 measurements including various stressing 2 tone responses.

2) I would like to explicitly add stability verification (for a wider range of loads) and various burst response verification tests for ac effects.

3) Yes, with the understanding that the Amp still operates in the real system as on the test bench. That is no oscillations, added noise, or ground loops are
introduced in the process.

4) Absolutely, with the marketing claim of "Best Measured Amp Ever".

Thanks
-Antonio
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Old 13th January 2012, 02:34 PM   #940
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Originally Posted by gk7 View Post
Do you have a larger scan or a link to this article ? Itīs hard to understand with this small section what exactly is the procedure.
www.passdiy.com/pdf/citation.pdf

Method is towards the end where sets the bias
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