John Curl's Blowtorch preamplifier part II

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PMA

PMA

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Joined 2002
pmacura.cz/audiopage.html
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I like the Howard's post as well.

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To me, these DBT - ABX supporters are responsible for current catastrophic quality of recordings (except for classical music).

'Scientifically proven' inaudibility of differences, hey? mp3 is fine, AAC is fine, everything is inaudible, who cares. 99.99% of population do not care, so it is statistically scientifically perfect, isn't it?
 
ThorstenL

ThorstenL

Previously: Kuei Yang Wang
Joined 2002
linkedin.com/in/thorsten-loesch-studio-raumklangg/
Hi,

simon7000 said:
The source is nothing more than an extension cord with a power transformer wired right across the outlet. The transformer steps 120 volts down to about 15 volts where it feeds a 2 amp bridge rectifier. The rectifier feeds a small relay that has the normally closed contact wired in series with the coil to form a small buzzer. The arc noise has to go back through the rectifier and transformer to make it into the AC line.
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Very smart set-up. A VERY long time ago in that country behind the seven seas and the seven mountains and the great wall of Berlin I had a doorbell that worked on the buzzer principle.

It made any radio reception impossible when rung and pumped enough rubbish into the mains to make through into my (all pro-studio stuff, balanced to boot) audio system, so even if I played music so loud I could not hear the doorbell itself, I sure as heck could hear the electrical noise it made in the speakers...

I never tried to fix it, as it was kind of useful...

Ciao T
 
SY

SY

Ex-Moderator
Joined 2002
SYclotron.com
john curl said:
SY would just LOVE to get me into a similar test, and then 2 decades later, my 'failure' could be broadcast far and wide, as well. It would serve me right.
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Not really, no. You've been explicit in that you cannot hear most of the differences you claim by ears alone. Why would I want to waste time proving that? I have less than zero interest in hurting or humiliating you; my interest is getting data and understanding reality. I assume that you're using "ABX" as an inaccurate shorthand for any sort of double-blind test-if you think that there's another controlled format that won't cause your ears to close up, then I'd be much more interested in helping you set it up. See my recent Linear Audio article for examples of other formats.

3 decades, BTW, but who's counting? We're getting old, John. :D
 
ThorstenL

ThorstenL

Previously: Kuei Yang Wang
Joined 2002
linkedin.com/in/thorsten-loesch-studio-raumklangg/
Hi,

janneman said:
No. The ONLY thing needed for any controlled listening test is trust in your ears.
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Most here probably have a healthy dose of self doubt. I know one person who has "aced" at least two, possibly three (my memory gets hazy for anything in the last milennium) ABX/DBT tests (all of which would be a great illustration of how not to do it BTW), where I struck out so badly, it was unfunny.

Of course, the difference between the two of us is the size of our ego. While some may think mine is so huge that they wonder how I ever get through any doors, it is in fact quite small and cute, easy to carry, a lot like a Pokemon...

Now this dude has an Ego that make s the "big heart" of the Girl in the ROger Sanchez Video "Another Chance" look way small.

So one may say that you have to be megalomaniac to "beat" ABX, as it magnifies any doubts you have and any sane person SHOULD have them...

Ciao T

PS, for those that do not visit "Clubland" on occasion (I still regularly hang out at clubs and occasionally consult on sound/light) here is the Video...

Roger Sanchez - Another Chance

"Do you need help? Who doesn't?"
 
J

Jakob2

Member
Joined 2004
hhoyt said:
Most everyone has a personal DBT comparison experience to relate, here is the most significant of mine: <snip>
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Very interesting post. :)

Afaik everybody who did some DBTs himself and conducted DBTs with other people will tell a similar story.

All in all, an interesting mish-mash of experiences. Conclusions:
1) A properly made cassette can be vanishingly close to a 16-bit well recorded digital source. Only four or so of the hundreds who took the DBT scored in a statistically significant way. Interestingly enough they were ALL in the cassette industry, particularly Dolby engineer Dennis Staats and our mastering engineer Ellen Threatt repeatedly scored perfectly. This proved that there were indeed audible differences. The test set-up was NOT obscuring the differences.
2) When the effects that these few people were detecting were pointed out to others, the other's scores improved markedly. This shows to me that familarity with the effects being listened for enhances the ability to detect the effect (duh).
3) DBTs are psychologically problematic.
4) Many people in the music industry have enormous egoes (duh), and some do not like exposing themselves to scrutiny, no matter how even the playing field. This makes them rely on their own criteria for claiming sonic superiority instead of agreed-upon criteria which can be mutually discerned and experimented with.
5) Different people can become accustomed to different listening environments (just as with dietary choices) and will not in the short-run like the sound in a different one.
6) My overall conclusion is that the variability of the test conditions when compared to a person's usual listening situation often outweigh the differences which may exist. However if open minds and critical discussions ensue in conjunction with the DBT, many people learn something and gain new insights.
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Every test is a difficult task and unfortunately an experimenter has to control it´s own bias mechanism to get useful results. Expecially difficult, i guess, because ever so often the main goal seems to be to "prove" an (or all) audiophile(s) wrong.

Despite the impossibility (due to theoretical reasons) it is not the best start point for good science.

It is common sense that tests include a lot of confounding parameters that have to be controlled and the biggest imponderability is the listeners himself.

But although a perfect test is not possible, most of the confounders are controllable.

The most important factors are: training of the participants (see for example ITU-R BS.1116; training sessions the whole mid-morning, tests in the afternoon) and positive/negative controls .

JJ can post in length (and quite funny) why training and positive/negative controls are mandatory and he normally emphasizes that listeners can reach incredible sensitivity levels in DBTs if these were done right.

And of course you are right, one can learn a lot about perception during the participation in controlled listening tests.
 
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