John Curl's Blowtorch preamplifier part II - Page 2268 - diyAudio
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Old 24th April 2012, 04:06 PM   #22671
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Originally Posted by ThorstenL View Post
It is not necessary to provide alternate experiments and outcome to expose bias and poor practice in extant ones and it then behoves the experimenter to correct his method, or be called fraud or worse with full justification...

Ciao T
True. One could just sit in the back row balcony, stick one's tongue out, and say nyah nyah nyah..your tests are wrong, your tests are wrong...

While you may be happy doing so, it is not a method I would be content with.

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Originally Posted by Wavebourn View Post
Don't relax if yo have no DC through resistor: excess noise modulates signal, and who knows what is worse.
Oh man, been there.

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Spoilsport!
Actually I'm so negative about the likelihood of a patent being of benefit to the "small" inventor these days (meaning not affiliated with a big-a$$ corporation) that I am siding with Don Lancaster: publish the idea and hope that at least no one will patent it and exclude your use of it.
I just publish also. When I present at a conference, I get an added 6 months time in Europe, but it doesn't matter anywhoo..


I still find it odd that many still believe that should a component measure well on the bench, those measurements will correlate completely to how it performs in the field...what a bizzare thought process which neglects so much of reality.

cheers, j
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Old 24th April 2012, 04:13 PM   #22672
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Hi,

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Originally Posted by jneutron View Post
True. One could just sit in the back row balcony, stick one's tongue out, and say nyah nyah nyah..your tests are wrong, your tests are wrong...
Well, it achieves (on evidence) exactly the same as extensive publications, so why not?

I grew up with the Muppet Show. I always thought the two old Geezers in that Balcony where having a Ball!

Ciao T
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Old 24th April 2012, 05:16 PM   #22673
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Two areas where we agree T.
First, I think that 'single blind preference testing' is the best way to tell if there is a significant difference between components.
Second, I don't need ABX, in fact ABX invariably makes virtually everything sound the same, once a few adjustments are observed, that being lowish distortion, same frequency response, and polarity, so what is the point?
Over the past 33 years, I have seriously tried and found problem with others ABX testing, and I put these problems in print, in 'TAA' very early on. Did anything really 'improve'? Not much.
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Old 24th April 2012, 05:17 PM   #22674
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Originally Posted by jneutron View Post
I still find it odd that many still believe that should a component measure well on the bench, those measurements will correlate completely to how it performs in the field...what a bizzare thought process which neglects so much of reality.

cheers, j
Are you moving towards the subjectivist camp? What do you miss with component measurements, and could the same be true for the whole audio chain, as in, it measures well, but it doesn't sound that way?
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Old 24th April 2012, 05:29 PM   #22675
KBK is offline KBK  Canada
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Originally Posted by vacuphile View Post
Are you moving towards the subjectivist camp? What do you miss with component measurements, and could the same be true for the whole audio chain, as in, it measures well, but it doesn't sound that way?
Oh, I kinda doubt that. I'm thinking that the stuff that john is dealing with most times, or some times, is of such a nature that the subtleties of signal in some minds and work, is the core point in question.

And thus, the static background conditionals in a lab will not equal the static/dynamic background conditionals of a field test.


This plays out in audio in the way the ear hears. Which is a core point I keep hammering at. One should endeavor to get to the 95% of correctly represented signal that one can. To do all the dances required to get there.

Then the real work begins. The work of getting the micro differentials in level and time correctly represented.. That is the entire content and singular aspect of signal that the ear hears and works with.

Thus, in audio design, as in cutting edge measurement equipment design...all the hard work of doing everything perfectly only lays the groundwork for the real work of getting the last 5% right.

In my understanding, knowing the last 5% is critical, this happens last, regarding finally figuring it out. Even if one has not got the first 95% percent figured out. This would be the norm, when you think about it. It is a 'eureka!' type moment, this discovery of the importance of the absolute correctness of micro signal propagation --being the singular aspect to be pursued.

the way I've observed it panning out, is that: Then one has to go back, address the 95% support structure over and over and over again, in execution test after execution test, in single cause analysis, for many years.

At the same time, understanding of the importance of the last 5% evolves..and then they (the 95% and the last 5%) tend to arrive on the scene at near the same time. In most audio engineers/designers, This cycle is a minimum of 10 years (wild *** guess-never seen it myself, ie no young 'hots shots' exist -except as legends in their own mind) and as high as 40-50 years, as a learning curve. In the vast majority of cases (history illustrating this aspect), it is going to be..oh.. at least 25 years.

We are talking about evolution in thinking and wiring, which involves learning in the standard sense and also learning in the hearing sense. the hearing mechanism, as a device that learns, can learn as the brain does in so called skills, education, etc. This is indisputable, but few realize it. they somehow cordon off the ear and it's capacity to learn... into some sort of static corral, like the length of their arm or the color of their eyes.

This is emphatically not true.

The ear/brain learns and refines, just as the brain is plastic in our understanding of education and personal evolution. thus the length of time, the learning curve that has to be bridged, in time,and work. The time period of oh, 20-40 years. It is a complex multifaceted endeavor, it is not a simple path.

Last edited by KBK; 24th April 2012 at 05:54 PM.
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Old 24th April 2012, 05:37 PM   #22676
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Originally Posted by vacuphile View Post
Are you moving towards the subjectivist camp? What do you miss with component measurements, and could the same be true for the whole audio chain, as in, it measures well, but it doesn't sound that way?
What jneutron most probably meant (maybe among other aspects) is, that testing under idealized conditions (i.e. not really reflecting the true field conditions) with idealized (for example steady state sinewave excursion) test signals and without considering the psychophysical processing of music by listeners, does most likely not tell about relevant effects that occur under real life conditions.


Which means that any DUT should measure well under these idealized conditions, but that is just the beginning.....
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Old 24th April 2012, 06:00 PM   #22677
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Originally Posted by john curl View Post
Two areas where we agree T.
First, I think that 'single blind preference testing' is the best way to tell if there is a significant difference between components.
Second, I don't need ABX, in fact ABX invariably makes virtually everything sound the same, once a few adjustments are observed, that being lowish distortion, same frequency response, and polarity, so what is the point?
Over the past 33 years, I have seriously tried and found problem with others ABX testing, and I put these problems in print, in 'TAA' very early on. Did anything really 'improve'? Not much.
It is better like to go outside of the room on BAF, smoke a sigarete on the porch, and try to imagine if there is a real orchestra behind open windows... Then decide if the result worth all that efforts to build such complex system or not...
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Old 24th April 2012, 07:13 PM   #22678
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Originally Posted by Wavebourn View Post
It is better like to go outside of the room on BAF, smoke a sigarete on the porch, and try to imagine if there is a real orchestra behind open windows... Then decide if the result worth all that efforts to build such complex system or not...
It is even better if you don't smoke, that is best left to experimental electronics, and not really even then.
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Old 24th April 2012, 08:42 PM   #22679
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Originally Posted by vacuphile View Post
Are you moving towards the subjectivist camp?
No, I am not moving in any direction. Tests on the bench do not reflect actual performance in the field. Test equipment is designed to reduce it's contribution to specific measurements, whereas one's listening room, ac outlets, source components, and speaker load will.

Even balanced equipment has it's issues.

As an example, If anyone wishes to check an amp properly, run it on the bench while pushing 100 mA pink noise current from the input ground to the IEC safety ground such that the current flows through the path of the chassis that the designer created.. Do not have a speaker connected, btw..you might blow a tweeter.

Quote:
Originally Posted by Jakob2 View Post
What jneutron most probably meant (maybe among other aspects) is, that testing under idealized conditions (i.e. not really reflecting the true field conditions) with idealized (for example steady state sinewave excursion) test signals and without considering the psychophysical processing of music by listeners, does most likely not tell about relevant effects that occur under real life conditions.
It's all about the changes in environment between the bench and the field. What the human response to image parameter changes is a whol nuther story.

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Which means that any DUT should measure well under these idealized conditions, but that is just the beginning.....
Yup.

cheers, j
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Old 24th April 2012, 10:54 PM   #22680
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Originally Posted by jneutron View Post
As an example, If anyone wishes to check an amp properly, run it on the bench while pushing 100 mA pink noise current from the input ground to the IEC safety ground such that the current flows through the path of the chassis that the designer created.. Do not have a speaker connected, btw..you might blow a tweeter.


cheers, j
Elliot has this setup on his site where he uses a bridge rectifier connected to safety ground in order to reduce ground loops. That would cause mayhem in this test!@# Still good for sound.

At the same time, I think it is primitive to mix up signal earth with safety earth. Signal earth should be treated with the same care as the signal itself. Safety earth is good for shielding. What this come down to is that an unbalanced XLR with 1 pin acting as signal earth i.m.o. is the preferable setup.
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