John Curl's Blowtorch preamplifier part II - Page 1240 - diyAudio
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Old 23rd May 2011, 05:54 PM   #12391
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Quote:
Originally Posted by simon7000 View Post
somebody will go build the ultimate line filters and still hook it up to poor product and then complain you are wrong.

ES
Yes Ed, I understand. There are at least 3 input paths for any amplifier. I tried to emphasize that some topologies are inherently more immune (if properly designed) than other. The complete lack of dynamic saturation issue is a perfect starting point.
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Old 23rd May 2011, 06:11 PM   #12392
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Quote:
Originally Posted by PMA View Post
Yes Ed, I understand. There are at least 3 input paths for any amplifier. I tried to emphasize that some topologies are inherently more immune (if properly designed) than other. The complete lack of dynamic saturation issue is a perfect starting point.
I could tell some interesting stories of commercial products that required filters on the loudspeaker lines top get the RFI out! But I won't!
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Old 23rd May 2011, 06:23 PM   #12393
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Quote:
Originally Posted by Charles Hansen View Post
Along those lines, late last year there was a full-page ad in TAS saying that you were coming out with a new zero-feedback amp. I haven't seen that materialize. Did I misread that ad, or is the amp still in the pipeline?
You are referring to the "concept amp" which is still in the pipeline for
release this fall. The prototype at that time was 0fb, but after reviewing the
results of our work with new devices this past year, the subjective
performance bar has been raised, and we are still working out the details.

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Old 23rd May 2011, 06:29 PM   #12394
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Quote:
Originally Posted by simon7000
but it seems no one understands it!
You keep asking us to do messy algebra, but have not told us why. Therefore it seems premature to conclude that we don't understand. Tell us what it is that you believe you understand, and we (allegedly) do not. We have already established that there will be an infinite series. The significance of the higher order terms depends entirely on the signal level, which you have not told us.
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Old 23rd May 2011, 06:36 PM   #12395
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Quote:
Originally Posted by janneman View Post
Well, Bruno's article being a technical articles I was assuming that the criterium was a reproduction as free from artifacts and coloration and harmonics and PIM and SID etc as possible. With that criterium, his article stands until other technical arguments refute it. Which, I noted, have not been offered by any of the supposedly heavy hitters here.
I do appreciate that such a criterium is different from, say, listener preference. By the same token, listener preference is just that and cannot be argued with.
Listener perception is everything where I come from. No distortion
analyzer has ever purchased one of my amplifiers.

I recall Bruno's article as being a nice overview of his thinking - obviously
I must have missed a proof as profound as you describe. As I have the
disadvantage of being at the coast, you will have to wait until I get back
for my response, unless you would care to email me another copy of the
piece.

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Old 23rd May 2011, 07:16 PM   #12396
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Right on, Nelson. His 'history' could use a little correction as well. IF he had asked, one of us, either Walt or me, could have brought him back to the right track. There is nothing new here. PIM is what I look for, not TIM, we solved the TIM problem over 35 years ago.
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Old 23rd May 2011, 07:20 PM   #12397
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Quote:
Originally Posted by Nelson Pass View Post
You are referring to the "concept amp" which is still in the pipeline for
release this fall. The prototype at that time was 0fb, but after reviewing the
results of our work with new devices this past year, the subjective
performance bar has been raised, and we are still working out the details.
Thanks for the info. Always look forward to your new designs.

If I weren't a complementary-symmetry kind of guy, it would be interesting to play around with the EPC devices. These are lateral parts with extremely high transconductance -- the best of both worlds. Too bad they can't use their process to make a P-channel part...
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Old 23rd May 2011, 07:22 PM   #12398
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Quote:
Originally Posted by Nelson Pass View Post
Listener perception is everything where I come from. No distortion
analyzer has ever purchased one of my amplifiers.
Damn cheapskate, tire-kicking distortion analyzers! When I see one come into my store, I throw it right out! I'm not going to waste my time with those looky-loos...
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Old 23rd May 2011, 07:34 PM   #12399
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Quote:
we solved the TIM problem over 35 years ago.
For signal bursts like 16MHz or 32MHz that come through PSU? You had no issues like this 35 yrs ago.
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Old 23rd May 2011, 07:46 PM   #12400
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No PMA, this is new, let's talk about it.
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