Yes, standard analogy witchcraft.
Like the belief that red food/wine/juice is good for the blood, voodoo dolls
transfer pain, or that pulverized rhino horns wake up the tired pecker.
OTOH they train police dogs on real pot or cocaine, so there might
be something true about it. 😕
Gerhard
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Thanks! I'm just going to back off feeding the monkeys for a while. It truly does get tiring and I have circuit layout to do.
Let's be fair, it is a pretty pointless discussion. There is obviously nothing wrong with op-amps when used wisely.
The fact that the 'there's nothing to see here' guys are here tells me there's more to it. Classic denial 😀
Yes, SY, I have studied personal magnetisim.
I could loan you the book (actually have one, quite old - it's about how to present oneself...)
But seriously, do you really think that what I know and/or see can effect what you hear??
I would be terribly hard to do a DBT if an opamp has to be plugged in... or should I hire a deaf mute who will stand behind a curtain and do the deed?
That will alter the results?
Has this been determined scientifically, with a DBT?
otherwise...
Short term AB and ABX tests are subject to a quantum level confounder that guarantees null results when discriminating fine changes.
Dan.
Dan.
LOL enjoyed the using dissing of blind testing, by the same camp of true believers... When I first did some I found it enlightening, those night and day differences when sighted diminished to zero in many cases. Interestingly some major changes were done to show we could discriminate differences under the tests.
On the side I will need some rhino horn very soon if anyone has any...
On the side I will need some rhino horn very soon if anyone has any...
Yes, absolutely. That's why double blind is the basic standard for any valid testing.
OK, I have an example as to how "design by T&M" can work out. A long time ago, I bought a few Symetrix SX202 preamps, and while they were generally well regarded, I found that some sounded good and some did not. I opened them up and found some differences among the various revisions, and tried to correlate their differences to my subjective observations.
While there were various output amps used, there were also different values for the three compensation caps used for the SSM2015 mike amp chip in the device, and it became clear after some simple part switching that this was an important determining factor of the preamp's performance.
After finding no useful explanations of what these three caps did from the chip doc or from any of the companies that used it, and no clear recommendation of their ideal values, I proceeded to do a "hill climbing algorithm" to incrementally optimize these three component values, using an AP2322 test set to determine whether my changes result in more or less distortion, measured using averaged FFTs of a conventional THD analyzer residual - the smaller the distortion spurs the better.
After a number of tests, changing the value of one cap, changing another, and also trying some altogether different sets of values and incrementally improving from each of those combinations, I settled on three values that seemed to work exceptionally well. Distortion remained low up to around 20-30kHz, and did not hit the wall at 3kHz like one version of the SX202. No other 2015 device ever used these compensation cap values, yet I could empirically prove that they would result in very good performance, better than any 2015 mike amp circuit I had seen.
At the end, I found the subjective performance to be very good, a large improvement from any stock SX202, and not just in the "you laid hands upon it, therefore it's better" sense.
Reliably detecting incremental improvement or degradation is needed to refine a circuit using the hill climbing algorithm. This might be really tough to distinguish with a pure listening test, but a test set can point to "better or worse or the same" a lot more reliably and quickly than a listener can. It's easy to get lost in the weeds, but I have shown myself that incremental improvements, many in a row, can result in a collectively significant audible improvement.
I'm pretty sure that most folks here would find that an amplifier whose distortion vs. frequency curve reaches a knee at 3kHz, above which distortion rises at 6dB per octave, will sound less clean than another amp, otherwise the same, that has the same knee at 20-30kHz. That is the improvement that I was able to accomplish using a test set and a simple empirical optimization procedure, with no listening tests at all. Yes, there was no "one step" that achieved this improvement - it was the sum of dozens of tests, guided by incremental improvements and degradations caused by trying different compensation caps and observing what happened at each step.
Further, no theory is required, or offered, as to why these values are ideal - they are ideal from a purely empirical standpoint. No other set of values can be show to produce better results.
From this, I can see the benefit of using relevant test and measurement tools, especially when they can facilitate honest, empirical optimizations. Sure, one has to decide which metrics are important, but that's not so difficult if your goal is transparency, since it's clear that less distortion is better, all else being equal.
If one's goal is not transparency, then your parameter space and your search mechanism is not deterministic. However, for the (what I'd like to think of as simple) goal of transparency, test and measurement is exactly what needs to be done, and it's not all that tough to use these tools to good effect.
Tilting at windmills. Why is THD only mentioned by people accusing other people of worshipping it?bear said:
Yes, we are deaf and stupid.john curl said:
That tells us a lot about the old guys, and not very much about the detectors. Same idea as silver cables giving sound extra brilliance, while copper cables make it sound dull. Mud cables dirty the sound, while interconnect bananas make it sound fruity.Max Headroom said:
i think it goes more like this: that guy actualy looking at data he got from blood samples to see was it placebo or there was some drug in blood.
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