The mobile charges are inside the material, and epoxy coating only helps to keep them inside (not that it matters much). Moisture would help to accelerate the process, but since they are coated that has no impact. I find them to be very stable as well.
Epoxy unfortunately isnt very stable, check out section 7 here: https://homepages.laas.fr/nolhier/ESREF2015/SESSION_C/PC_7.pdf , this also explains the underlying mechanism. And yes, the capacitors do not see 4kV but the layers are of course much thinner - the mechanism should be similar.
Partial discharge in foil capacitors is in research (https://ieeexplore.ieee.org/document/7726577) as they are used extensively in power electronics. Again, not a very subtle application, but similar mechanism.
So, could mobile charges in the dielectrica explain the issue? I think it is a likely candidate. What do you think about the mechanism that MennoVdV brought up - compression of the dielectric layer under influence of the electric field?
Epoxy unfortunately isnt very stable, check out section 7 here: https://homepages.laas.fr/nolhier/ESREF2015/SESSION_C/PC_7.pdf , this also explains the underlying mechanism. And yes, the capacitors do not see 4kV but the layers are of course much thinner - the mechanism should be similar.
Partial discharge in foil capacitors is in research (https://ieeexplore.ieee.org/document/7726577) as they are used extensively in power electronics. Again, not a very subtle application, but similar mechanism.
So, could mobile charges in the dielectrica explain the issue? I think it is a likely candidate. What do you think about the mechanism that MennoVdV brought up - compression of the dielectric layer under influence of the electric field?
Hardly. Changes in dielectric in a very stable capacitor such as silver mica would be so small that audibility is very questionable. Another thing is that such changes would not always improve sound.
What makes your claims not very believable is that these happen in a phono stage which by default has relatively high noise and distortion. So claiming to hear minute differences which cannot be measured and are always an improvement in a phono stage sounds just like another audiophile cliché.
I suggest you invest in a high-quality ADC (e.g. Cosmos ADC) which can measure far below the limits of your phono stage.
Thanks for the proposal, I do have similar measurement capabilities.
We are back to square one - you do not believe what I was telling about my and my co-listeners' experiences, to begin with, even while I was trying to come up with attempts to explain you would not move, as your last post clearly shows.
I'm outta here.
We are back to square one - you do not believe what I was telling about my and my co-listeners' experiences, to begin with, even while I was trying to come up with attempts to explain you would not move, as your last post clearly shows.
I'm outta here.
Besides the low credibility of this anecdotal "science" another I see another issue that makes me wonder:
Given you and your friends hear some audible improvements - how can you be sure these are caused be some tiny effects inside some caps?
Or even - how can you be sure that it#s the caps that make the improvement?
Given you and your friends hear some audible improvements - how can you be sure these are caused be some tiny effects inside some caps?
Or even - how can you be sure that it#s the caps that make the improvement?
If you and your friends hear something that is below the measuring capabilities of Cosmos ADC it would be truly remarkable. So why don't you show some measurements instead of just anecdotes? Or you could make recordings of new and well-aged devices and post them here.
If some believer of flat-earth theory attempts to explain his theory to you, do you change your view just because of his attempt?
I'm curious what other factor might be the cause of the issue. I haven't had any issues with the first ACA since that initial experience with low gain, and I did not experience the same thing with my second build.
Of course, I recognize that my measurement technique might be the culprit, but that was a one time opportunity that can't be replicated. I cannot swear that my measurement process or volume setting on the preamp were rigorously identical. I can't even tell you the total hours of operation between low and high measurements, but the differences were huge. I say that, not to disagree with you, but to establish context.
"Scientific" is not when is not done, what is claimed to be done:
In case of audio: audio:
listening, hearing;-)
In case of audio: audio:
listening, hearing;-)
No human is completely unbiased. Biological brains don't work that way. Your particular bias in this case appears to be to actively deny the existence of anything that does not meet your definition of "proven."
Aside: Proof only exists in mathematics. Physical science is more of a process, not a result. The process produces evidence (which is often noisy, but which often settles out over time).
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You already said that in Post #272. Nobody understood it then and I doubt that anyone will understand it now just by repeating it a second time.
Maybe it's just the use of ordinary English, and it's hard to measure the numerical meaning of adjectives, but in your earlier post you say "they sound very different" and "How big is the difference? It is remarkable even to some untrained ears."
In the later post it's "And, the rest of the system needs to be up to the task, as the differences are subtle, not big."
I'm not arguing who hears what, I just want to show why many of us are so insistent on formal tests.
Probably people will give some variety of arguments about why formal tests should be required, at least that's been the case in the past.
One possible factor that may be involved is a feeling/intuition that any physical effect should easily measurable and easily correlated with human hearing. Part of the reason for that intuition/feeling may be that a sound card is pretty easy to use for measuring PSS HD/IMD. Also its pretty low cost, at least at the entry level. And there is powerful free software. Not only that, but audibility has been formally correlated with human hearing by university scientists.
The next step in reasoning is that if other things were likely to be audible then similar formal science would already have been performed on that as well. Of course, that's not necessarily correct logic. What if the reason HD/IMD has been correlated with human hearing by scientists already is because its the easiest possible thing to measure and correlate. Easy to do on a small-ish scientific budget and only needing a few researchers (who in those days were being paid by government grants and university salaries, and who had to find something to publish that would be doable within their limited resources).
Also perhaps consider that the quality of amplifiers, speakers, dacs, etc., used in research some decades ago were not as capable of high accuracy as the best we can do today. For one example, can we trust dac jitter audibility thresholds using test system amplifiers with .1% HD? Personally, I have my doubts (especially if using today's ultra low distortion electrostatic speakers).
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If you really believe that I suggest you never get on an airplane again.
Why? Commercial airplanes are statistically safer than cars even though airplanes sometimes crash. Boeing 737 variants are not without a history, for one well known example.
Aside: Billions of dollars are spent on making airplanes safe. How much is spent on hi-fi system audibility research?
Aside: Billions of dollars are spent on making airplanes safe. How much is spent on hi-fi system audibility research?
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But your statement suggests that physical science is nothing more than a process and the results cannot be trusted.
Those who do hear a difference will often respond "if you can't hear it, your ears just aren't good enough".
A major problem I see with the audiophile verbiage is that the terms used are vague and ill-defined, if defined at all. Take pace, rhythm, and timing (PRaT) for example. What does that even mean? What does it mean when a piece of equipment is "musical"? Some will describe a particular sound as "detailed" whereas others will describe the same sound as "harsh", even though they both listen to the same sound of speaker cone breakup. There's just so much noise in the subjective descriptions that I can't extract any data from it.
On the other hand, if I measure -130 dBc THD under some condition, make a change to the circuit, and measure -135 dBc THD under the same conditions, I can say with confidence that the THD has improved by 5 dB, assuming measuring a 5 dB difference at those levels is within the capabilities of the instrument used for the measurement.
I also know from experience that getting to the -130 dBc level takes real work and experience, so I see such numbers as an indicator of good circuit design, in particular if the circuit also performs well on many other parameters. Having the equipment to make the measurement also shows some commitment to quality. Anyone can claim something sounds good. Few can back it up with measurements.
I would love to see a more scientific approach to the subjective side of audio. There are just too many confounding variables in un-controlled tests for me to draw any conclusions from them.
Tom
Again, from your statement:
"Physical science is more of a process, not a result".
If that is true, then clearly we can't trust the results.
"Physical science is more of a process, not a result".
If that is true, then clearly we can't trust the results.
I said the process produces evidence (often the evidence is noisy too, but over time it should work out to be the best evidence we have). What's not to trust about strongly supported evidence? It's not a true/false thing. Its a statistical probability thing.
Not only that, but there is the mathematics of Fuzzy Logic, some of the concepts of which can be applied to fuzzy thinking. The idea that things/ideas/objects/etc., can have partial membership in multiple distinct logic sets. The degree of membership is expressed a probability distribution. But its not a probability of true or false. Its more like a probability of a particular degree of set membership.
Not only that, but there is the mathematics of Fuzzy Logic, some of the concepts of which can be applied to fuzzy thinking. The idea that things/ideas/objects/etc., can have partial membership in multiple distinct logic sets. The degree of membership is expressed a probability distribution. But its not a probability of true or false. Its more like a probability of a particular degree of set membership.
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