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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 20th January 2014, 05:31 AM   #47061
john curl is offline john curl  United States
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No, because I rejected it in the HCA2200, in order to get it through the audiophile listening tests. I would LOVE to find out why, as it should have been virtually 'perfect'.
For the record, I do use IC's, just not in my best designs.
For all else being equal, I still find discrete design an advantage over any IC's that I can find today.
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Old 20th January 2014, 07:41 AM   #47062
marce is offline marce  United Kingdom
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John Curl's Blowtorch preamplifier part II
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As far as design teams, unless you are working for the Jet Proplusion Laboratory, which I have, everything is a comprimise in the commercial world. Just look at the performance distribution histograms in data sheets. Why don't they just sell the best ones? Why do they even have a distribution?
Er! not just the JPL, there are many areas of electronics where compromise, life/mission critical designs. As to thermal issues, there are newer thermal efficient packages, and thermal engineering for assemblies is well known and studied, something that I don't see a lot of in 'high end audio'. A simple circuit with op-amps in thermally efficient packaging could be built and easily tested, this as you can imagine is done for a lot of designs, especially say vehicle communication systems for military/aerospace where the circuitry is subjected to some quite harsh temperature testing. Quite easy to design and build and op-amp based pre where the temperature of the active devices could be controlled by a the correct PCB design and some active heat sinking.
 
Old 20th January 2014, 07:59 AM   #47063
canyoncruz is offline canyoncruz  United States
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Let's do it! My analysis software includes a black box for TEC's. The one thing it can't do is the transition response of the TEC itself, like from 85 to 22 C otherwise it's very accurate

Last edited by canyoncruz; 20th January 2014 at 08:01 AM.
 
Old 20th January 2014, 09:38 AM   #47064
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
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Originally Posted by canyoncruz View Post
I say we slap a cooler on some op amps in an audio circuit and see if there is a change in the audio.
You're certainly welcome to do so. The problem is that there's no real problem. Unlike things such as dynamic compression, polar patterns, frequency response, noise, level, and a few dozen other well-characterized auditory phenomena, no-one has demonstrated any audibility (in real ears-only listening tests, not the make-believe "listening tests" that support the niche where John makes his money) of gain blocks made from ICs. The choice of discrete (or tubes or what-have-you) is dictated by fashion or individual taste unrelated to actual sound, not real listening data.

The problems could be designed out then and aren't in the cards now. The only plausibility argument is 40 year old notes explaining to engineers of that time how to avoid problems with early analog chip designs that were already on their way out. But if that's what you want to chase, despite the inaudibility of IC-based gain blocks designed by modern engineers, go for it.
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Old 20th January 2014, 09:47 AM   #47065
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Originally Posted by SY View Post
... no-one has demonstrated any audibility (in real ears-only listening tests...

...the inaudibility of IC-based gain blocks designed by modern engineers...
Did not Mooly and PMA conduct a few ABX (Foobar ABX plugin) listening tests here on diyaudio.com with positive results ?
 
Old 20th January 2014, 10:38 AM   #47066
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
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Originally Posted by gk7 View Post
Did not Mooly and PMA conduct a few ABX (Foobar ABX plugin) listening tests here on diyaudio.com with positive results ?
That's not the variable they were testing. Additionally, it was pointed out during the setup of these tests that they were poorly structured and controlled.

Unfortunately, competence in engineering (and those are two very competent engineers) does not equal competence in experimental design for sensory testing.
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Old 20th January 2014, 11:08 AM   #47067
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Some of the tests had many errors, some were flawless. Only ABX results were accepted and files were matched within 0.01dB amplitude range and also time aligned. You may doubt anything if you want. I agree that there were only few flawless tests, but they have shown that some listeners have great abilities to discern differences and the others do not. What I doubt is an ABX test with 20 people in one room, regardless 'scientific' preparation. Technically it is always incorrect. But, ABX test (ABX foobar plug-in) may be very useful.

1) some people are able to discern lossy compression
2) some people are able to discern 16 bit from 24 bit sound file
3) some people are able to discern wire from opamp

These are my ABX conclusions. Some people are unable to hear any of the differences hereabove. Statistics is useless, as hearing abilities are SO different.

Last edited by PMA; 20th January 2014 at 11:12 AM.
 
Old 20th January 2014, 11:16 AM   #47068
PMA is offline PMA  Europe
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Originally Posted by john curl View Post
No, because I rejected it in the HCA2200, in order to get it through the audiophile listening tests.
Oh sorry, I missed the proper amplifier type. Anyway, why not to make own listening tests before using ANY opamp? They are still so different in sonics, even the newest parts.
 
Old 20th January 2014, 11:21 AM   #47069
SY is offline SY  United States
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John Curl's Blowtorch preamplifier part II
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Some of the tests had many errors, some were flawless.
Flawless? Not even close. And the right way to do it to get significance and to remove some obvious non-auditory variables was suggested and heartily ignored.

I freely admit that I don't have your engineering chops, but you have to understand that likewise you don't really "get" sensory testing and how to do it and interpret it properly.
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Old 20th January 2014, 12:03 PM   #47070
jacco vermeulen is offline jacco vermeulen  Netherlands
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Originally Posted by marce View Post
there are newer thermal efficient packages
Silicon carbide ?
 

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