Count 1 more for all receivers sound the same - Page 16 - AVS Forum
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post #451 of 540 Old 02-13-2013, 08:28 AM
 
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Originally Posted by kbarnes701 View Post

...the Earth was not the centre of the universe.  Why?

You guys have some funny spellings in your odd English version of the American language. wink.gif
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post #452 of 540 Old 02-13-2013, 08:35 AM
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Originally Posted by arnyk View Post

That's because FR measurements are not omitted during the setup of an ABX test - we call it level matching. The point being that it isn't a problem if both devices have non flat frequency response as long as they have the same FR +/- 0.1 dB.

Your post show a strange attitude - you shouldn't be demanding this and that from me - it is all in the documents that I have cited. ABX is almost 40 years old, and it is well-documented. It is also common sense for most people.

I believe you have the attitude problem. I demanded nothing. I had two concerns. Apparently you are assuming the role of the educator on this thread. A good educator should be patient and share their knowledge rather than belittle others who have less knowledge.

1. You stated that you level match various frequencies, yet you do not call this eq. All my research on audio equalizing calls your method equalizing.
2. I asked about room measurements. All ABX testing shows that people can not discern any difference in the sound of two amps. I accept this, however it stimulates me to ask about measurements. We are constantly told that we should take measurements to validate what we assume is a different sound. If it is heard it can be measured is the rule of thumb. IMO, if it is not heard it should still be backed by measurements to verify if we did in fact miss something that we should have heard.
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post #453 of 540 Old 02-13-2013, 08:41 AM
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Originally Posted by MUDCAT45 View Post

d. A good educator should be patient and share their knowledge rather than belittle others who have less knowledge.

The University that I graduated from told us at freshman convocation that they were a lot more interested in teaching us how to find information for ourselves than teach us a lot of specifics.

Many of us students, myself included frustrated the professors by being intellectually lazy and paid the price in grades and ego-shattering comments.

In this case I provided you with links to the information that answered your question long before you repeatedly berated me for not providing it.
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post #454 of 540 Old 02-13-2013, 08:53 AM
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Originally Posted by MUDCAT45 View Post

1. You stated that you level match various frequencies, yet you do not call this eq. All my research on audio equalizing calls your method equalizing.

I've been wondering about this myself, though not from quite the same angle as you. I'm interested in the mechanics at this juncture.

In a perfect world, with two pieces of perfect equipment with perfectly flat and matched response curves, you'd select any arbitrary frequency and level match the two while playing the same sine wave at that frequency through each of them. When the output voltages match to within some small value, you have level matched the equipment to within that value across the spectrum.

However, if the frequency response were different between two pieces of equipment, say one had rolled off highs and a big dip around 400 Hertz, where does one level match?

That being said, my concept of equalizing in audio is more about shaping the frequency response curve (whether to a flat response or some desired house curve) for a single chain of equipment at the listening position.

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post #455 of 540 Old 02-13-2013, 08:53 AM
 
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Originally Posted by arnyk View Post

Yes. The DBT ensures that the opinons of the listeners don't matter. The only exception is when a listener doesn't play the game and just randomly colors in their answer sheets.

Short of mind reading and even with reasonable self-examination, the prejudices and opinions of the listener may be non obivous to him. More to the point, home and audio store comparisons of receivers usually include so many uncontrolled variables that the two products probably sound different for reasons that have nothing to do with the inherent sound quality of the products.
It always seems to. For example, we often do a sighted evaluation of the equipment before the DBT. People seem to have definite opinions about product sound quality, even if the subsequent DBT fails to find evidence of an audible difference.
I think the most important thing is that without a complete set of controls, there are biases both personal and technical that will strongly influence the outcome of the test. Controlling the biases will often result in an absence of evidence of an audible difference in sound quality. Bench testing will usually show that there is no technical reason to expect a difference.

Thanks!
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post #456 of 540 Old 02-13-2013, 08:55 AM
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Quote:
Originally Posted by MUDCAT45 View Post

Quote:
Originally Posted by arnyk View Post


1. You stated that you level match various frequencies, yet you do not call this eq. All my research on audio equalizing calls your method equalizing.

Its only called equalizing if you change something to obtain the level match. I've already said that we generally had no need to change anything because the equipment was generally that good.
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2. I asked about room measurements. All ABX testing shows that people can not discern any difference in the sound of two amps. I accept this, however it stimulates me to ask about measurements. We are constantly told that we should take measurements to validate what we assume is a different sound. If it is heard it can be measured is the rule of thumb. IMO, if it is not heard it should still be backed by measurements to verify if we did in fact miss something that we should have heard.

You seem to think that good equipment with audible problems is easy to find. Please explain why that is so.

I now know that nothing that should have been heard was missed. A few of us expected that the equipment would turn out to be good enough in the day. Most did not. Were we surprised or what!

In general the equipment was bench checked before the ABX tests. The level matching procedures would have caught most problems that would show up in actual use but not bench testing.

Room measurements are the worst way I can imagine to evaluate the performance of anything but loudspeakers and rooms. Trying to evaluate good electronic equipment that way is futile.
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post #457 of 540 Old 02-13-2013, 09:02 AM
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Originally Posted by JD in NJ View Post

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Originally Posted by MUDCAT45 View Post

1. You stated that you level match various frequencies, yet you do not call this eq. All my research on audio equalizing calls your method equalizing.

I've been wondering about this myself, though not from quite the same angle as you. I'm interested in the mechanics at this juncture.

In a perfect world, with two pieces of perfect equipment with perfectly flat and matched response curves, you'd select any arbitrary frequency and level match the two while playing the same sine wave at that frequency through each of them. When the output voltages match to within some small value, you have level matched the equipment to within that value across the spectrum.

That is pretty well what happened. One source of frustration was coarse and hard to set level controls. We had some precision level setting equipment that we added to the systems which added only negligable changes other than easy level setting.
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However, if the frequency response were different between two pieces of equipment, say one had rolled off highs and a big dip around 400 Hertz, where does one level match?

We usually bailed on the test and said that the piece of equipment with the weird response was not worthy of the effort of a listening test.
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That being said, my concept of equalizing in audio is more about shaping the frequency response curve (whether to a flat response or some desired house curve) for a single chain of equipment at the listening position.

We used the best rooms we could, except when we had a advocate who demanded a certain room.

In those days the AES etc were trying to develop a standard high quality listening room that was called "The IEC Room". One of our members had such a room at his place of business and we made extensive use of it.

I think he was headed in the direction of ITU recommendation BS 1116-1 if he wasn't already there. 1116-1 came about a decade later.
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post #458 of 540 Old 02-13-2013, 09:03 AM
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Thanks!

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post #459 of 540 Old 02-13-2013, 09:48 AM
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Quote:
Originally Posted by cybrsage View Post

Quote:
Originally Posted by arnyk View Post

Trouble is that sighted evaluations are 0.0% accurate.

Would the test be accurate if the listeners did not care at all about which wins? For example, if I am demoing two amps in my home and I really do not care which one is better than the other, would seeing them make a difference? I realize it is not a study test then, just curious about real world application. I include complete ignorance of brands and also include money not being an object - that way those two biases are missing.

Not really (for the sighted test). The problem is that the biases we all suffer from are subconscious. It is impossible to remove them.

 

In the sighted test you propose, you would have the appearance of the two units - one might 'look' better than the other or be slightly bigger or heavier: that could colour your perceptions right from the get go.

 

One might be a 'respected' brand and the other might be a little known brand - again your perception would bias towards the respected brand.

 

One may cost much more than the other and it is reasonable (although incorrect) to assume that a $10,000 amp will outperform a $1,000 amp. And so on.

 

The only way to be sure to remove subconscious prejudicial biases is to not know which amp is playing at the time of your evaluation.

 

Also, if you are demoing the amps in your own home, how would you arrange for instantaneous switching between the two units?  How would you level match them to 0.1dB?

 

The only way to be sure that you are genuinely hearing a difference, if you perceive a difference, is to do a true blind test. Preferably double blind, where the circumstances are controlled. This seems to me to be so incredibly obvious I am a total loss to understand the fanatical resistance it generates amongst 'audiophiles (I am not referencing you in this). 

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post #460 of 540 Old 02-13-2013, 11:05 AM
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Quote:
Originally Posted by arnyk View Post

Most would look at actual performance and prefer your AVR.

Here are some measurements of the frequency response of your AVR:



and, here are some distortion measurements for it:



Just for reference, what to expect from an AVR.



and distortion measurements which are unforuntatly formatted differently:



Fig.10 Denon AVR-4800, one channel driven, distortion (%) vs 1kHz burst output power into 8 ohms (black trace), 4 ohms (red), 2 ohms (blue), and 1 ohm (green).

Please notice that the frequency response plots have vastly different vertical scales since the AVR had so much better frequency response. Also please note that the AVR was set for "small" speakers and the bass roll-off was due to the AVR's internal crossover.

To compare apples to apples use the following table:

Convert dB down to percent

dB % (per cent)
60 0.1
80 0.01
100 0.001

Bottom line is that the high end amp had so much distortion and such bad frequency response that it actually probably sounded different. When set for flat response, the AVR would probably pass a straight wire bypass test. Also please note that the AVR was capable of delivering immense amounts of power into 8 and 4 ohm loads. Something like 300 wpc into a 4 ohm load.

here are its specs:

http%3A%2F%2Fusa.denon.com%2Fus%2Fdownloads%2Fpages%2Finstructionmanual.aspx%3FFileName%3DDocumentMaster%2FUS%2Favr4800_ownersmanual.pdf&ei=Oq0bUZrFE8vv0QGW-YHQDg&usg=AFQjCNE6rigeh_EqSWJytiQS8n4YK4wL6g

Power amplifier
Rated output: Stereo (2ch driven)
(All properties shown are only 125 W + 125 W (8 Ω/ohms, 20 Hz ~ 20 kHz with 0.05% T.H.D.)
for the power amplifier stage.) 130 W + 130 W (8 Ω/ohms, 1 kHz with 0.7% T.H.D.)
Surround
125 W x 5 ch (8 Ω/ohms, 1 kHz with 0.7% T.H.D.)
Dynamic power: 170 W x 2 ch (8 Ω/ohms)
270 W x 2 ch (4 Ω/ohms)
350 W x 2 ch (2 Ω/ohms)
Output terminals: Front/Center: 6 ~ 16 Ω/

The Wavac was pretty much done by the time it reached 50 watts.

I guess I should of wrote your AVR and my power amps sound better than those $350,000 Wavac mono blocks?

What if ABX testing was conducted using the Wavac and that AVR and found the listeners preffered the Wavac?

I also have read that tube amps have mostly 2nd order distortion or something like that? Tube amp users claim that tube amp distortion is less offensive compared to SS amp distortion, any truth to that or is it some just think the colored sound "sounds" more enjoyable or closer to real music somehow?

Cheers!
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post #461 of 540 Old 02-13-2013, 11:07 AM
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Its only called equalizing if you change something to obtain the level match. I've already said that we generally had no need to change anything because the equipment was generally that good.

As in: Generally not, unless it would be identifiable enough to void the test


You seem to think that good equipment with audible problems is easy to find. Please explain why that is so.

I never said that. Perhaps you assume that because I have not tried to inflate your ego. BTW, I do think most equipment is very good to excellent.


I now know that nothing that should have been heard was missed. A few of us expected that the equipment would turn out to be good enough in the day. Most did not. Were we surprised or what!

In general the equipment was bench checked before the ABX tests. The level matching procedures would have caught most problems that would show up in actual use but not bench testing.

Room measurements are the worst way I can imagine to evaluate the performance of anything but loudspeakers and rooms. Trying to evaluate good electronic equipment that way is futile.

If all equipment sounds/performs the same then the room measurement should be the same with all equipment.


You also mentioned that amps with mismatching + or - FR was eliminated. So I now understand the procedure. Either sample equipment until it all matches or when possible tweak until it does and no one will know the difference.
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post #462 of 540 Old 02-13-2013, 12:13 PM
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Have there been any current product tests done that are available to read? Or are the posted tests from years ago?

Would be nice to have some test results for current product comparisons for those of us shopping now. I have been very interested in this thread but would like to be able to utilize accurate testing for assistance in selecting new products. That is, if there are any audible or measurable test variances in the products. Yes I totally understand that competitive products in a comparative price range should sound similar or even identical with features, functions, aesthetics being the determining factors for selection. Still, would love to read stuff that is up to date.
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post #463 of 540 Old 02-13-2013, 01:21 PM
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Originally Posted by arnyk View Post

We usually bailed on the test and said that the piece of equipment with the weird response was not worthy of the effort of a listening test.

So you intentionally excluded equipment that could have shown differences during the test. Seems just a tad bit biased... wink.gif

I think the blanket statement "All amps sound the same" should be amended to "All amps that measure the same sound the same."
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post #464 of 540 Old 02-13-2013, 01:24 PM
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So you intentionally excluded equipment that could have shown differences during the test. Seems just a tad bit biased... wink.gif

I think the blanket statement "All amps sound the same" should be amended to "All amps that measure the same sound the same."

Since the point of the test is to compare equipment in proper working order, it makes sense to exclude defective equipment.
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post #465 of 540 Old 02-13-2013, 01:26 PM
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I guess I should of wrote your AVR and my power amps sound better than those $350,000 Wavac mono blocks?

If fidelity to the original sound is your criteria for sound quality, then there are few if any modern SS amps or AVRs that don't sound better.
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What if ABX testing was conducted using the Wavac and that AVR and found the listeners preffered the Wavac?

ABX testing is not a relevant choice for preference testing. If I reinterpret your question to say:

"What if blind preference testing was conducted using the Wavac and that AVR and found the listeners preferred the Wavac?"

The sound quality of the Wavac is extraordinarily changed by the impedance curve of the speakers it drives, so the result obtained relates to only that loudspeaker and the Wavac should probably be penalized for that problem.
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I also have read that tube amps have mostly 2nd order distortion or something like that?

That is an audiophile myth. Tubed amps includes both push-pull tubed amps and SET tubed amps. Push-pull tubed amps have vanishingly small amounts of even order distortion simply because they are push-pull. SET amps have primarily even order distortion but do also have odd order. This is illustrated by the following spectal analysis:

http://www.stereophile.com/content/wavac-sh-833-monoblock-power-amplifier-measurements



You can see that this amp has both odd and even distortion as well as a goodly dollop of hum in the forms of harmonics of 60 Hz at 180, 240, 300 Hz, etc.

I think the rule mentioned above has been broken every which way but loose! Call it an audiophile myth. ;-)
Quote:
Tube amp users claim that tube amp distortion is less offensive compared to SS amp distortion, any truth to that or is it some just think the colored sound "sounds" more enjoyable or closer to real music somehow?

Two words: Sighted evaluations.

These people are tubed amp advocates who umm advocate tubed amps. Everybody who is surprised or thinks this has much of anything else but their personal preferences can grab a pointed cap and take a seat in the nearest corner! ;-) Call it an audiophile myth.
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post #466 of 540 Old 02-13-2013, 01:31 PM
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Originally Posted by tsaville View Post

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Originally Posted by arnyk View Post

We usually bailed on the test and said that the piece of equipment with the weird response was not worthy of the effort of a listening test.

So you intentionally excluded equipment that could have shown differences during the test. Seems just a tad bit biased... wink.gif

No, at that time we were investigating whether or not there were some unknown unmeasurable explanations for people's belief that these amps sounded different. If there was a measurable difference that was large enough to make us think that the amp pretty much had to sound different due to measurements, then the amp disqualified itself.
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I think the blanket statement "All amps sound the same" should be amended to "All amps that measure the same sound the same."

Thing is, no two amps, even the different channels of a stereo or multichannel amp actually measure the same. The amps in a 5.1 AVR measure enough different that you could probably name them by their measurements. Ditto for stereo amps.

So, since no two amps measure the same, your statement becomes moot.

You can try again.... ;-)
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post #467 of 540 Old 02-13-2013, 01:33 PM
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Originally Posted by Theresa View Post

Since the point of the test is to compare equipment in proper working order, it makes sense to exclude defective equipment.

But how do you know if it's defective or if the frequency response is the result of the design (whether intentional or not)? You would need to test multiple instances of the same model to verify, I would think.
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post #468 of 540 Old 02-13-2013, 02:06 PM
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Originally Posted by arnyk View Post

No, at that time we were investigating whether or not there were some unknown unmeasurable explanations for people's belief that these amps sounded different. If there was a measurable difference that was large enough to make us think that the amp pretty much had to sound different due to measurements, then the amp disqualified itself.

If the measurable difference is consistent with numerous samples of the identical brand/series and was an intentional design by the manufacturer it is not a flaw. Maybe inaccurate but not a flaw.


Thing is, no two amps, even the different channels of a stereo or multichannel amp actually measure the same. The amps in a 5.1 AVR measure enough different that you could probably name them by their measurements. Ditto for stereo amps.

So, since no two amps measure the same, your statement becomes moot.

ABX becomes moot if it only proves that all amps measuring = sound =.


You can try again.... ;-)

Is there validity to this extraction that I nave read about a particular ABX test?---

"Or perhaps you remember the ABX test that was likely the most damaging to these pseudo-scientists, comparing a known audibly defective amplifier to a perfectly working one? All listeners were able not only to hear the defect in the amplifier but able to describe it's distorted sound under normal listening conditions. However using ABX testing protocols none were able to identify the difference between the defective and the working amplifier with any statistical significance, thus proving beyond a shadow of a doubt that ABX testing does not work. In addition I am sure none of the participants would be willing to take home the defective amplifier, I am quite sure they would all want the perfect working one!"
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post #469 of 540 Old 02-13-2013, 02:07 PM
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Originally Posted by arnyk View Post

No, at that time we were investigating whether or not there were some unknown unmeasurable explanations for people's belief that these amps sounded different. If there was a measurable difference that was large enough to make us think that the amp pretty much had to sound different due to measurements, then the amp disqualified itself.
Thing is, no two amps, even the different channels of a stereo or multichannel amp actually measure the same. The amps in a 5.1 AVR measure enough different that you could probably name them by their measurements. Ditto for stereo amps.

So, since no two amps measure the same, your statement becomes moot.

You can try again.... ;-)

Ok, how about "All amps that measure close enough that there is no discernible difference to the human ear sound the same." biggrin.gif
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post #470 of 540 Old 02-13-2013, 03:36 PM
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Quote:
Originally Posted by tsaville View Post

Quote:
Originally Posted by arnyk View Post

No, at that time we were investigating whether or not there were some unknown unmeasurable explanations for people's belief that these amps sounded different. If there was a measurable difference that was large enough to make us think that the amp pretty much had to sound different due to measurements, then the amp disqualified itself.
Thing is, no two amps, even the different channels of a stereo or multichannel amp actually measure the same. The amps in a 5.1 AVR measure enough different that you could probably name them by their measurements. Ditto for stereo amps.

So, since no two amps measure the same, your statement becomes moot.

You can try again.... ;-)

Ok, how about "All amps that measure close enough that there is no discernible difference to the human ear sound the same." biggrin.gif

That is true, but I read your smiley as indicating that you know that its a truism. ;-)
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post #471 of 540 Old 02-13-2013, 03:46 PM
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Quote:
Originally Posted by MUDCAT45 View Post

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Originally Posted by arnyk View Post

No, at that time we were investigating whether or not there were some unknown unmeasurable explanations for people's belief that these amps sounded different. If there was a measurable difference that was large enough to make us think that the amp pretty much had to sound different due to measurements, then the amp disqualified itself.

If the measurable difference is consistent with numerous samples of the identical brand/series and was an intentional design by the manufacturer it is not a flaw. Maybe inaccurate but not a flaw.


Thing is, no two amps, even the different channels of a stereo or multichannel amp actually measure the same. The amps in a 5.1 AVR measure enough different that you could probably name them by their measurements. Ditto for stereo amps.

So, since no two amps measure the same, your statement becomes moot.

ABX becomes moot if it only proves that all amps measuring = sound =.


You can try again.... ;-)

Is there validity to this extraction that I nave read about a particular ABX test?---

"Or perhaps you remember the ABX test that was likely the most damaging to these pseudo-scientists, comparing a known audibly defective amplifier to a perfectly working one? All listeners were able not only to hear the defect in the amplifier but able to describe it's distorted sound under normal listening conditions. However using ABX testing protocols none were able to identify the difference between the defective and the working amplifier with any statistical significance, thus proving beyond a shadow of a doubt that ABX testing does not work. In addition I am sure none of the participants would be willing to take home the defective amplifier, I am quite sure they would all want the perfect working one!"

I believe that the above text originated here: http://www.positive-feedback.com/Issue56/abx.htm

I don't recognize what he is talking about.

It was discussed here:

http://www.hydrogenaudio.org/forums//lofiversion/index.php/t90547.html

I don't think that they recognized it, either.

One of the posters at the Hydrogen Audio forum who commented is actually James Johnson, the Bell Labs researcher who was one of the inventors of MP3 and recently retired as head scientist of DBX. http://home.comcast.net/~retired_old_jj He's a walking encyclopedia of these things and if he didn't recognize it, I don't know who would. Court of last resort: Ethan Winer who posts around here frequently.

No matter, the anecdote refers to an alleged test that is riddled with logical flaws.
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post #472 of 540 Old 02-13-2013, 04:10 PM
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^^^ I'm not aware of that test either.

--Ethan

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post #473 of 540 Old 02-13-2013, 04:12 PM
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The problem with quotes on the Internet is that they are difficult to verify.

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post #474 of 540 Old 02-13-2013, 04:25 PM
 
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Court of last resort: Ethan Winer who posts around here frequently.

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^^^ I'm not aware of that test either.

--Ethan

eek.gif He mentioned your name and POOF!!! You appear! I am slightly frightened by that...
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post #475 of 540 Old 02-13-2013, 04:30 PM
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Originally Posted by cybrsage View Post

Quote:
Originally Posted by arnyk View Post

Court of last resort: Ethan Winer who posts around here frequently.

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Originally Posted by Ethan Winer View Post

^^^ I'm not aware of that test either.

--Ethan

eek.gif He mentioned your name and POOF!!! You appear! I am slightly frightened by that...

No magic, just a PM.
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post #476 of 540 Old 02-13-2013, 05:24 PM
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So you intentionally excluded equipment that could have shown differences during the test. Seems just a tad bit biased... wink.gif

I think the blanket statement "All amps sound the same" should be amended to "All amps that measure the same sound the same."

there was a sloo of british amps in the early digital era that rolled off the highs. people could hear the rolled off highs. not a surprise. no real sense reproducing via test what everybody would agree on - if two amps' output is measurably different at levels known to be audible they will sound different. if you happen to have a denon audyssey equipped receiver, you should find it easy to hear the difference between the audyssey curve and "audyssey flat," because there is an audibly significant measurable high end roll off in the audyssey curve.

you can still find the stereophile test where bob carver took one of his amps and made it sound like a high end tube amp (maybe a C-J) essentially bu adding a resistor at the output to recreate the tube amp's higher output impedance which skewed frequency response

and if you want to purchase an amp that skews the frequency range, that's dandy, and we'd all be astounded if you could not hear the difference between it and a flat amp.
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post #477 of 540 Old 02-13-2013, 05:42 PM
 
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Originally Posted by Abraham Lincoln
The problem with quotes on the Internet is that they are difficult to verify.

I would add to that. The more pushy and condescending a person on the internet is, the less value their posts have.
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post #478 of 540 Old 02-13-2013, 09:50 PM
 
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No magic, just a PM.

You take all the mystery out of it. frown.gif
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post #479 of 540 Old 02-14-2013, 05:01 AM
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Originally Posted by cybrsage View Post

Quote:
Originally Posted by arnyk View Post

No magic, just a PM.

You take all the mystery out of it. frown.gif

Even I was a little surprised by the speed of reply. Coincidence, I guess.
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post #480 of 540 Old 02-14-2013, 08:53 AM
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i would have been even more surprised if he had answered your question before you asked...rolleyes.gifbiggrin.gif
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