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opamps THD+N/IMD/SNR measurements don't mean jack IRL, so let it go humm'kay? - Page 9  

post #121 of 134
Quote:
Originally Posted by Head Injury View Post

If it were an ABX test (which tests the ability to tell a difference, not the ability to identify the test products) I expect the pros would have succeeded. When people know what they're supposed to be comparing, they'll make up plenty of crap. And if they fail, it might just be because their assumptions about certain kinds of gear were false. It doesn't mean they didn't hear a difference that is clearly there, like between two completely different violins.

 

If you're attempting to use that as a defense against ABX and blind testing in general, your reasoning is flawed.

 

So many people try to cite that article and those similar as proof that blind testing is useless rolleyes.gif

Quote:
Originally Posted by Paul Clark View Post

You are projecting.


I think your context was a little unclear as well and you might have been misunderstood.  I couldn't tell WTF you were implying either so I just gave the most reasonable interpretation of the experimental results.  I have actually seen people make arguments as lame as, " DBT fails to identify the Stradivarius.  We know the Stradivarius sounds better.  Therefore DBT doesn't work." which is how your post got interpreted.  I've actually seen even lamer arguments than that here on Head-fi.

 

Quote:
Originally Posted by Paul Clark View Post

BINGO!  Congratulations - you go to, er, the back of the bus? evil_smiley.gif


I've been back here for nearly 2 years already...

post #122 of 134

FYI...just out today:

 

http://www.scientificamerican.com/podcast/episode.cfm?id=stradivarius-fails-sound-test-versu-12-01-04

 

 

post #123 of 134
post #124 of 134

amazingly lame "critique" from a non-expert in psychoacoutic testing  - only a "rally the base" article not a useful addition to "the debate" - the subject is treated much better by threads here even

 

 

 

post #125 of 134
Quote:
Originally Posted by Rdr. Seraphim View Post

Some more food for thought: http://www.avguide.com/forums/the-difference-between-medical-dbts-and-audio-dbts


Keith W. is strawmaning quite a bit I think, he is considering what audio objectivists already consider bad practice.

 

- Sample size and quality: he has a point here, no one has millions of dollars to recruit thousands of participants for audio DBT, Meyer & Moran did manage 500 though if my memory is right.

- Short periods of time on an unfamiliar system: but most audiophile objectivists would recommend to DBT on your own system at home on familiar material

- Not knowing what we are looking for: However most objectivists would consider that the steps to an audio ABX consist in first identifying what's different in sighted conditions, image width, more treble..., and once those have been identified, try to do the same blind.

- Power calculation: Sure, but considering that no serious DBT has ever had a positive result for (normal) cables, calculating how many positives one would need to have a relevant result is premature.

 

His conclusion somewhat makes sense though, we should organize more rigorous DBTs.

Quote:
I think that audio DBT's have their place, but only well designed ones. Most DBT's I read about are absolutely pathetic.

 

But audio objectivists are already aware of the limitations and requirements of DBT, I would almost tentatively say that a lot of half baked DBTs are done by subjectivists trying to score a point.

post #126 of 134

DBT is just a small part of experimental control and non-laughable testing standards, obviously.  It's not always necessary or feasible, though preferred when applicable, and experimental design certainly doesn't stop there...

post #127 of 134
Quote:
Originally Posted by maverickronin View Post

I think your context was a little unclear as well and you might have been misunderstood.  I couldn't tell WTF you were implying either so I just gave the most reasonable interpretation of the experimental results.  I have actually seen people make arguments as lame as, " DBT fails to identify the Stradivarius.  We know the Stradivarius sounds better.  Therefore DBT doesn't work." which is how your post got interpreted.  I've actually seen even lamer arguments than that here on Head-fi.

 


I've been back here for nearly 2 years already...


Have you considered a reading comprehension course?

 

Wow! 2 years?  In reading comprehension?

 

post #128 of 134

Before we all start mudslinging, let us focus on the real subject of this thread: leeperry's utterly fallacious reasoning. It's kinda fun, playing "Spot the Ludicrously Large Logical Hole," "Spot the Ad Hominem" "Spot the Biases At Work"...

 

His recent posts  provide an incredibly good example of confirmation bias, whereby the subject subconciously dismisses anything which disagrees with their current position and takes as gospel anything that doesn't, although I'll have to say the effect isn't meant to be quite this strong. Case in point: Ignores everybody and all links until someone agrees with him, then cites them as the "technical answer" which proves he is right... (Prediction: Will either not respond to my post or claim that I am biased LOL IRONY and spin it into reasonably well disguised personal attack)

 

I am reminded strongly of a quote from a creationist mentioned in the introduction of The God Delusion (note this is purely for purposes of demonstrating the absence of logic in what leeperry says rather than to start an inappropriate debate) - I shall paraphrase:

 

"Even if all the evidence in the world turned against my ideas, I would still believe them, as they are based on the irrefutable word of God."

 

Here God is sighted listening. Some people find it incredibly difficult to understand that their ears and other people's ears are not infallible, not on a logical level, but on a "But I heard it" level. Hence they construct elaborate arguments to justify their position to themselves, which are terrifying fascinating in a worrying sort of way - very few are able to admit what the above individual does - that their position is essentially irrational (I don't think he does completely: I think he might have been quoted out of context!).

 

Once they admit that, I'll leave them to itbiggrin.gif

 

@Maverickronin:

 

A member of the Stereophile team presented a paper at the AES some time in the 90s. His conclusion was that there are unmeasurable, completely unquantifiable things in audio which are impossible to verify as any attempt to verify them with blind testing and the like renders them inaudible. The mechanism by which this occurs is not important as the differences are clearly from the equipment, because.


Edited by Willakan - 1/5/12 at 9:14am
post #129 of 134
Quote:
Originally Posted by Willakan View Post

A member of the Stereophile team presented a paper at the AES some time in the 90s. His conclusion was that there are unmeasurable, completely unquantifiable things in audio which are impossible to verify as any attempt to verify them with blind testing and the like renders them inaudible. The mechanism by which this occurs is not important as the differences are clearly from the equipment, because.


In related unfalsifiable hypotheses I have the unfailing ability to predict winning lotto numbers as long as I never write them down, tell anyone else what they are, or buy a ticket myself...

post #130 of 134
Quote:
Originally Posted by SanjiWatsuki View Post

The basic conclusion is that massive amounts of negative feedback is the best and results in no higher level harmonics, feedback in moderation from 0dB to 70dB creates higher level harmonics which are reduced as feedback increases, and no feedback results in no higher level harmonics but more distortion at the more natural lower level harmonics (Fig 10). Furthermore, these higher level harmonics can combine when a complex combination of tones (the basic definition of music) is played to create a large amount of distortion. Feedback in general reduces the overall measured distortion. Very cool stuff.

l7ZGH.jpg

 

In this way, we're both right. If negative feedback is engineered incorrectly and in the wrong amounts, it will add higher level harmonics which can combine to very high amounts of distortion and make it sound worse, despite having better measurements. With properly implemented negative feedback, this effect can be entire mitigated, it's just a matter of engineering enough negative feedback or a circuit which mitigates the potential for more higher level harmonics. Still, feedback is not evil. 

 

It is worth noting that in the complex tone graphs we are dealing with much higher amounts of power and an 8 ohm speaker load. Op amps struggle with this and I agree 100% that op amps should not be used in that context and that discrete amplifiers have the advantage. The raw numbers suggested by the article will likely not be close to the actual numbers experienced by an amp based design for headphones. 


 

Note from the back of the bus to Mr. LeePerry,

 

Please tell us exactly what conclusions you drew from this? Cos I'm a little bit confused..............confused_face_2.gif

 

Warning: technical blablabla ahead!
Please note:

You do not properly design in an amount of feedback into an Op Amp circuit.

You design to meet a specific or desired amount of gain for your application, in our case typically 0-20 dB of gain in most headphone applications.

In an Op Amp circuit, it's not unusual to see 60-80 dB of feedback in the middle of the audio bandwidth.

 

Regards,

CJ

 

post #131 of 134

I mentioned confirmation bias earlier: Wikipedia notes how it causes people to misinterpret things that strongly criticise their position as supporting it - even if they are aware that it criticises them at the time, they are relatively likely to either forget it or incorrectly remember it as supporting their views (the former is rather more likely, admittedly).

 

I was mistaken in my statement that leeperry had found a statement which appeared to support him: I apologise unreservedly for any offense caused.


Edited by Willakan - 1/5/12 at 9:42am
post #132 of 134
Quote:
Originally Posted by Willakan View Post

A member of the Stereophile team presented a paper at the AES some time in the 90s. His conclusion was that there are unmeasurable, completely unquantifiable things in audio which are impossible to verify as any attempt to verify them with blind testing and the like renders them inaudible. The mechanism by which this occurs is not important as the differences are clearly from the equipment, because.

Quote:
Originally Posted by maverickronin View Post

In related unfalsifiable hypotheses I have the unfailing ability to predict winning lotto numbers as long as I never write them down, tell anyone else what they are, or buy a ticket myself...


It's gotta be quantum mechanics.

post #133 of 134
Quote:
Originally Posted by Head Injury View Post

It's gotta be quantum mechanics.

 

Actually my pet dragon tells me telepathically...

 

 

post #134 of 134

Now you've done it. Someone will promptly talk about how stupid we are for rejecting the audiophile hypothesis more than "tentatively" and some other people will insist that there isn't "enough evidence." to make a call either waybiggrin.gif*

 

 

*The above post contains elements of humour. Got to be careful on this sort of thread...

 

 

Normally I would now say "Back on topic:," but I'm not sure this thread has a topic other than how silly those are who think that the premise that opens it makes any sense.


Edited by Willakan - 1/5/12 at 10:57am
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Head-Fi.org › Forums › Equipment Forums › Sound Science › opamps THD+N/IMD/SNR measurements don't mean jack IRL, so let it go humm'kay?