John Curl's Blowtorch preamplifier part III

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#21,742
mountainman bob said:
I usually expect disappointment......sometimes (not often) I’m pleasantly surprised.

I can’t be the only person in the world that has enough computational skill between the ears to separate results from expectations?
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This is confusing because of the psychoacoustic element, I wouldn't necessarily call expectation bias psychoacoustic, I'm not sure? Expectation bias you might be able to separate but I wouldn't bet on it.
 
#21,743
Markw4 said:
No. We have a problem in that we want to be able to measure performance of equipment designed for human perceptual use, but we don't have a sufficient understanding of human perception. What we have been doing for a long time is measuring what our technology makes it practical to measure, and telling ourselves it effectively works perfectly for its intended end use by all humans in existence.

The fact is, we don't know enough about human perception to make broad claims about all humans in existence.

We have heard from Earl Geddes in casual conversation that hearing research to date is applicable to roughly 95% of the population. If he is correct then we clearly don't know about all humans in existence.

When PMA states that an professional symphonic musician can hear things that PMA cannot hear, we accept that without debate.

When people claim they can hear distortion in an amp that has been measured at -120dB HD @1kHz, we somehow assume the person is claiming to hear HD at -120dB @1kHz, and we think that can't possibly be true. Actually, it is quite possible the person making the claim doesn't mean they hear what we tend to assume they mean. What they may be hearing is something we didn't measure for.

Below are a couple of FFTs of a dac output. Both were digitized at 24/192, the test tone was actually driven at -10dBFS, but the display readout is relative to 0dBFS of the A/D. The only difference between the two is that the the test sine wave frequency was changed by 3Hz, from 997Hz to 1KHz. When a spectrum changes that much with only a 3Hz change in test tone frequency, no wonder if it were to attract the attention of a listener. People tend to notice non-stationary effects more than stationary. Also, no wonder if some distortion effects in some devices might get missed depending on the test regimen used and nature of distortion production in the device. This dac may have also be subject to the ESS HD 'hump' that not everyone tests for.
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Is that not an FFT binning issue? On the QA401, it automatically adjusts the test signal frequency to ensure you don't generate spurious data.

Maybe I am wrong - Scott needs to weigh in here . . .
 
#21,744
Evenharmonics said:
You mean you think he was correct. Unless you consider yourself as the final arbiter of matters regarding tests.
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Regarding ABX, I think I know even better than MMerrill (and my opinions is even more extreme than his). Why? Setup an ABX test and I can show you that I will beat you (or anyone that you champion if you can't hear) at every turns. If I could show it to you, who do you think should be the final arbiter?

But he's not just talking about ABX! But I don't want to have too many topics to discuss either 🙂
 
#21,745
picowallspeaker said:
There's a huge ( infinite) difference from playing test tones on headphones to listening to some reproduced music by the stereo
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PMA said:
Yes, e.g. room reflections (different at every participant), not speaking about differences in speakers. That's one of the reasons why headphones are much more suitable to find details and subtle differences. And more generally similar, than speaker + room combination.
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With headphones you negate the travel in space of the sound waves.
e.g. when an instrument is recorded, the sound expands in space then it dies.
The same happens in re-production: the sound expands in space then it dies

The "speaker + room combination" doesn't work anymore, it has never worked
🙄
 
#21,746
scottjoplin said:
This is confusing because of the psychoacoustic element, I wouldn't necessarily call expectation bias psychoacoustic, I'm not sure? Expectation bias you might be able to separate but I wouldn't bet on it.
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PMA, are Psychoacoustic expectations when you imagine what your going to imagine?😀

And yes Scott I can go into testing new gear with no expectations....It’s not really that hard.
 
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#21,747
mmerrill99 said:
No, I'm not saying that - read what I posted with more care
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I've read it multiple times. Same result. You claim that there's no difference between sighted and blind tests, they all have to be validated by individual testing.

mmerrill99 said:
And herein lies the problem - both sighted listening & the types of blind listening tests we see on forums are equivalent in their level of subjectivity/objectivity - ask ScottJ - he now understands that both are just a bit of fun to be shared on fora.
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mmerrill99 said:
Any different to sighted listening - bit of fun? IMO, it is just the same as any reported listening impression (sighted or otherwise) i.e. to be verified by one's own experience/listening. They are - again to be verified (if one is bothered) by one's own experience/listening.

I'll say it again - trying to elevate simplistic forum ABX testing above the 'bit of fun' that it is, is just plain wrong but it will continue on here as I see already
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#21,748
Markw4 said:
No. We have a problem in that we want to be able to measure performance of equipment designed for human perceptual use, but we don't have a sufficient understanding of human perception. ...

When people claim they can hear distortion in an amp that has been measured at -120dB HD @1kHz, we somehow assume the person is claiming to hear HD at -120dB @1kHz, and we think that can't possibly be true.
Actually, it is quite possible the person making the claim doesn't mean they hear what we tend to assume they mean. What they may be hearing is something we didn't measure for. .
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VERY good input, on my point of view, Mark.
There is nothing we can explain, by an intellectual demarch, looking at measurements, about the difference in sharpness/details/micro-dynamic between various DACs that all measure low low under what one could reasonably tell as possible to hear.
As an example.
Or the change we all(?) have experienced, oversizing a PSU in an amp, that measure exactly the same at normal listening levels between the two PSUs.

Adding an instrument to a mix in studio tells-you, dayli, how high you have to push the fader to make-it discernible in the all landscape. We are far, far from the >-100dB of a modern DACs distortion level. And yet ?

We still have a lot to discover, and that's all the fun of this audio activity.

If everything was as simple as some people seem to believe, this forum would not exist ;-)
 
#21,751
Bonsai said:
Is that not an FFT binning issue?
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A number of factors may be involved. I did not try investigating since I decided to abandon that dac for other reasons. If binning issues, the spurs are probably best aligned with the bins when they are at a maximum level and the energy is not spread between adjacent bins. In that case the distortion is too high for me to consider acceptable, and there is also too much HF junk making its way out of the dac.
 
#21,754
syn08 said:
I've read it multiple times. Same result. You claim that there's no difference between sighted and blind tests, they all have to be validated by individual testing.
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Do you really think what I posted "the types of blind listening tests we see on forums" equates to what you claim I said "So you are essentially saying there are no listening tests (sighted or blind) that can be extrapolated to an entire population, therefore all tests need to be individual."

Really? You do need to pinch yourself (& hard) if you are still suffering from such a heavy bias/shortfall in comprehension
 
#21,757
#21,758
hhoyt said:
Who knew our perception was not solely air molecules moving...?😉

Howie
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Yea, who knew - revelations abound 😎

Note the use of the term "Psychoacoustic experiments" in the research paper - it doesn't mean that they are testing for imaginings/delusions.

It's often seen on audio forums this confused use of the term trying to equate it to delusions - it simply reveals their lack of knowledge of what they are talking about.
 
#21,760
Markw4 said:
You may have forgotten that I made a list of few minor changes that I though would make foobarABX much more user friendly. Attempts to find source code, the original author, or someone to write a new version were unfortunately unsuccessful (I did have one volunteer programmer, but he backed out after thinking through how much work writing a new ABX would take). I wouldn't have gone to that effort if I thought the program was properly designed for good usability in the first place.

<snip>
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Mark4, have you tried to post some proposals (or to contact the developers) in the Foobar-forums over at hydrogenaud.io ?
 
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