John Curl's Blowtorch preamplifier

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#8,343
KBK said:



The reality is that only psychotics themselves say such things as ' these high end audio guys must be liars as I don't hear it and I don't understand it'. That is a vocalized reflection of a limited intellect and personality. Nothing more.
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Except you're forgetting that the same high end guys demonstrably don't hear it either, once the visual stimulus has been taken away . There's ample proof of that (even JC himself admits it, in this very thread).

And this thread so predictably turns into another sledging match ... so much about superior intellect and personality of golden eared ones.
 
#8,344
Hannes,
Your 2nd statement is correct,
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The first one is correct as well.
The dynamic range of hearing is about 135dB according to the logarithmic SPL scale, where the power doubles for each 3 dB increase, 45 times = an increase of 32 trillion in power level. Not too bad.
The lower threshold of hearing is very close to 0 dB, just above the noise level of blood flow, molecule collisions with the eardrum and 135 dB, the threshold of pain.

Please note, pressure is an objective physical parameter. The relationship between SPL and subjective sensitivity to sound is a different story. The ear`s characteristics show considerable departures from linear scales, for example its harmonic distortion spectrum (called the aural harmonic envelope), as a result of adaptation to the (savanna) environment.

The peculiarities of hearing do have importance in sound reproduction, if anyone was in doubt.
 
#8,345
John - in "contact" to me means actually most resistors in a preamplifier. Even those in the regulated power supply,
those in the DC servo, those in a CCS, etc etc.

Some people only use good ressitors in the input filter, output, and feedback, but an all out pre amp should have the best resistors in almost every position in the complete amplifier.

How do you define "contact audio signals"?




Sigurd

john curl said:
I think that all resistors that contact audio signals are important.
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#8,346
I like to make the analogy of a chef in a restaurant:

a top class chef needs hig quality ingridients to make a first class meal (= one, two, or three stars in Guide Rogue former Guide Michelin)

a top class chef can make a very good meal from ordinary quality ingridients but cannot make a first class meal from these ingridients

a stadard/good chef cannot make a first class meal from even high quality ingridients


Sigurd

john curl said:
Back to the challenge of layout and parts quality. What do I mean by parts quality? Do I mean high prices, pretty finish, both?
Think about faked products that look the same for all intents and purposes. Is a fancy watch that is counterfeited that same, for all practical purposes as an original?

Is all chicken that is to be cooked, really the same quality, and therefore taste?
Is all fruit at the supermarket the same as if you could pick it from a tree or buy it from the local farmer?

For all intents and purposes, the watch, the chicken, and the fruit look and appear to be the same. At least until you use the watch for awhile, or eat the prepared chicken or fruit.
Now, if you have no appreciation of these differences, then the minute differences that I work with will be of no use to you. For you then: 'Parts is parts'. It is the same for chicken or audio.

Now what are the differences in audio parts, including caps, connectors, and wiring?
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#8,347
@myhrrhleine

That only applies to direct conscious awareness.
We hear it all, even though we are not readily aware of it.
and, we can train ourselves to be more aware.
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I posted scientifically proven facts, straight from lecture notes for recording engineers, since most stuff written here is more or less hear-say.

If you have something to backup your statement I would be very interested.

@Lumba

You didn't care to read my posting. 135dB is the range over which the ear can adjust itself. At any moment it can perceive only a 60dB window within this range. This is a proven fact, again straight out of the lecture notes, not some hear-say.

I can mail the professor to get some references to scientific studies if you wish, but I guess you can read any book on hearing to get this confirmed.

Have fun, Hannes
 
#8,348
Today we would probably laugh when we read hifi requirements defined in DIN 45500 standard in the sixties.

I have studied electro-acoustics at the university in the seventies. Many definitions of perceiving threshold limits have changed since these days (according to development of electronics and drivers). Even well know Fletcher-Munson curves.

Who says we know everything today?
 
#8,349
Lumba Ogir said:

The lower threshold of hearing is very close to 0 dB, just above the noise level of blood flow, molecule collisions with the eardrum and 135 dB, the threshold of pain.
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And it goes without saying, you can hear a resudual of say 3dB (twice the 'hearing absolute zero') while being pounded 120+dB at a rock concert ?
Sure.

Have a good look at some of the available (peer reviewed) technical papers at say http://www.mp3-tech.org/ , it speaks volumes about hearing (in)ability.
 
#8,354
PMA said:
My point is that we should be open-minded and not to rely on current level of knowledge, especially when psychoacoustics (not pejorative) is still not well explored.
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Pavel, I wonder why the null test procedure is not more fully explored, being at this time ample availability of equipment and software to distill as much information as one cares imagine.

Whenever results from device A are closer to null than device B, and still someone claims decive B is better sounding, we have a smoking gun for self deception or worse.

Rodolfo

PS. Granted there is not such thing as perfect NULL, but this can be qualified with some confidence, that is why I mention rather heavy data massaging to extract results, i.e. spectral composition, correlated an uncorrelated spurious etc.
 
#8,357
PMA said:
My point is that we should be open-minded and not to rely on current level of knowledge, especially when psychoacoustics (not pejorative) is still not well explored.
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You can study the ear physiology and the psychoacoustic until the cows come home, this will not change the dynamic range of the human hearing. You may find an explanation as of why, but this will not change the reality that you can't hear a whisper during a wild rock concert. Neither can you hear metal film resistors through 1% (at best) distortion speakers.

And yes, I am one of those supposingly deaf engineers and I'm d*mn proud of it. And very happy that I am not supposed to make a coin in this very sad audio industry.
 
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