John Curl's Blowtorch preamplifier part II

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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.
 
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.
 
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.
 
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.
 
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.
 
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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.
 
Well PMA, I wish that I had listened to the 2200 BEFORE I released it to the public and to audio reviewers. Later, I modified a number of units by REMOVING the part, and adding a simple wire to make it work without itis input IC, AND my associates and I listened to the change. It was there, all right. It was a BIG mistake that I relied on test equipment only, and not the ears of myself and my associates. It is always tempting to not bother with simple listening tests.
 
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Wow , you guys got going with this , i will try this one for giggles , did the chemist participate ?

We wondered where you all were :D

Here's another fun one, hardly cutting edge but fun non the less.
Purely Subjective Test

and there is another set of files available by pm only. Whether you could detect any audible difference on those would be very interesting.
 
Would everyone who contributes, PLEASE read about IC thermal tails as first put up by Solomon, 40 years ago, and INDEPENDENTLY MEASURED by National Semi. in an app note. Let us get on track with this.
How important is it? I do not know. Is it real? YES

BTW you misinterpret several of those plots, the thermal problems are gull wing in shape (you know thermodynamics no negative heat here). Several of those plots are simply the beta roll-off of 40 year old lateral pnp technology. Come on folks is this about high-end or JC sitting around the campfire with his posse spinning yarns?
 
BTW you misinterpret several of those plots, the thermal problems are gull wing in shape (you know thermodynamics no negative heat here). Several of those plots are simply the beta roll-off of 40 year old lateral pnp technology. Come on folks is this about high-end or JC sitting around the campfire with his posse spinning yarns?
Yes to your question (both).
 
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