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post #1 of 98 Old 02-28-2008, 02:45 AM - Thread Starter
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Has anyone here conducted or attended a DBT that was designed specifically to measure differences in soundstage and imaging precision?

By soundstage I mean, depth, width and height, using a reference CDs specifically for this purpose (for example, Chesky).

By imaging precision, I mean the width of the image of the singer's mouth or an instrument. (i.e., it it a yard wide or just a mere 6 inches).

(IMHO, it is more difficult to differentiate between CDPs based other subjective criteria, for example, transparency, high frequency extension, midrange "liquidity" - especially if the listeners are not keenly familiar with the source material. I feel this may explain, at least in part, why traditional DBT's fail to pick differences between CDPs.)

Note that a DBT that is specifically designed for evaluating soundstage can not, by design, have more than one test subject listening at a time, since only one listener can be in the sweetspot of the listening room.

I have attemped such a test in my setup using three different sources:
a Panasonic DVD-F87 changer,
a Marantz CC4300 CD changer,
and an Onkyo DX7555 CDP.

They were connected through the analog out hooked up to my Tube Audio Design TAD-150 preamp. This was a sighted test and was it was not conducted under strict level matched conditions. Interconnects used were Audioquest Jaguar. The test required me to switch the interconnects between players, since I don't have enough pairs and I wanted to take the IC out of the equation.

Source material used:
1. FIM Audiophile Reference CD II (Track 1)
2. Patricia Barber, "A Fortnight in France" (Track 1)

My findings, after repeating the listening test several times:
(a) Once the output volume from my speakers was at a medium listening level or higher, the soundstage becomes stable for each player (i.e., the width, depth and height do not change when you slightly increase or decrease the volume within +/- 15%). Thus, IMO, SPL level matching specifically for soundstage has no real significance.

(b) All three players produced a soundstage which extended beyond the edges of my speakers.

(c) The sonic images produced by each player were stable and precise between tests. (I used a notepad to write the "location" of the "image" of the singer or instrument relative to positions in my listening room. The same track section(s) were used for all players and in repeat tests with the same player. I repeated the test a few times for each CDP and each time got the identical location of the image.)

(d) The is a slight improvement (5 - 10%) in soundstage width by the Marantz over the JVC. The depth seemed to be the same between the two, but the Marantz produced more focused images.

(e) There is also a slight improvement (5 - 10%) in soundstage width, but a significant improvement in depth (15%), by the Onkyo over the Marantz.

(f) The biggest improvment was in the Onkyo's ability to image precisely and realistically. (For example, with the Onkyo its is possible to pinpoint the vocalist's mouth to within 4" - 6". With the Marantz the singer's mouth is about a foot wide with the same recording). The realism is just uncanny. The Onkyo is the most "holographic" among the three. Another wierd thing is the difference in soundstage height. For example, the voice of the announcer in the Patricia Barber CD is comes from a couple of feet higher with the Onkyo (8' versus 6').

CONCLUSION:
It is actually quite easy to tell differences in CDPs by looking at soundstage alone. And, one does not need to be a golden eared audiophile.

CAVEAT:
IMHO, one's system should be at a certain level of transparency in order to produce a good soundstage with precise, holographic imaging. To get it there, at the minimum, one needs a pair of good phase-coherent speakers, quality components, and proper speaker placement. IME, one also need take care of the power side of things in order to bring the noise floor down and have a pitch black background. A hospital grade or better wall outlet and a good power conditioner are important. Things like decent cables and vibration damping also play an important role. (I found that vibration damping significantly helped my Marantz CC4300 changer's ability to image.)

C N Machani
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post #2 of 98 Old 02-28-2008, 05:26 AM
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You didn't match levels accurately. You didn't control bias. A bias controlled test is not only possible but it is reasonably simple. One person does the listening form any position desired, the other person handles the equipment substitutions and level matching so the listener doesn't know what he is hearing. The listener identifies product A or B and the equipment person scores it right or wrong. About 10 or 15 random substitutions should do it. I do appreciate the effort. However, you just provided another subjective biased opinion like all the others in high end audio and you used more words this time than the last. You need to understand that what you did is not a valid test for audibility.

I encourage you to go further. It's great that you are trying to get to the truth. Do you need detailed instructions on how to control bias in your listening test?
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post #3 of 98 Old 02-28-2008, 06:34 AM
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In addition to FMW's comments, you'd need the ability to lock your head in one position. Otherwise room anomalies may influence your perception.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #4 of 98 Old 02-28-2008, 06:51 AM
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Quote:


This was a sighted test and was it was not conducted under strict level matched conditions.

Well, then, here are two very plausible explanations for what you claim to have heard:
1) You imagined it.
2) It was caused by differences in output levels.

Now, go back and do the comparison blind and level-matched, and tell us what you find.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #5 of 98 Old 02-28-2008, 09:06 AM
 
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The only way to test for differences in soundstage/imaging only would be if our perception of this were not influenced by other factors. Unfortunately, it is.
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post #6 of 98 Old 02-28-2008, 10:29 AM
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This is just DUMB even as a DBT. It is completely a personal taste thing. Really you think it had a wide soundstage? I thought it sounded thin and harsh. What one person thinks is a wide stage may be someone elses worst sound.

And the test could never be repeatable. Why? Because the biggest variable, your ears, change daily and sometimes even by the hour. Based on your mood,the weather,stuffy head etc..

Just another buch of audiophile tomfoolery.
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post #7 of 98 Old 02-28-2008, 10:30 AM
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Also, the idea that a DBT would be designed to detect a specific type of sonic difference misunderstands the issue. Any difference in soundstage caused by CD players would have to be the result of changes in levels or frequency response in the two channels. So any DBT methodology that was sensitive to changes in levels and FR would be sensitive to changes in soundstage.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #8 of 98 Old 02-28-2008, 11:09 AM
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All we try to do in a bias controlled test is to determine whether or not there is an audible difference, regardless of what the cause of the audible difference is. If there is an audible difference then sorting out the cause is usually easier to do with measurements than with listening tests.

What Machani doesn't want to accept is that the audible differences he experiences are due to differences in perceptual hearing and not from an actual audible difference the products themselves. If he were to engage in a bias controlled test with these products he would almost certainly find that there is no audible difference of any kind between them whether it relates to soundstage or anything else.

We know this because that is what virtually all bias controlled listening tests of DA converters has shown. One unit could be defective or "voiced" and sound different but the products he is talking about aren't "voiced" and are probably functioning just fine. His ears and brain are functioning just fine as well. The flaw is in his willingness to understand it all.
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post #9 of 98 Old 02-28-2008, 10:37 PM - Thread Starter
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Quote:
Originally Posted by mcnarus View Post

Also, the idea that a DBT would be designed to detect a specific type of sonic difference misunderstands the issue. Any difference in soundstage caused by CD players would have to be the result of changes in levels or frequency response in the two channels. So any DBT methodology that was sensitive to changes in levels and FR would be sensitive to changes in soundstage.

Soundstage and imaging are most influenced by time and phase accuracy between the two channels, not so much by frequency response.

C N Machani
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post #10 of 98 Old 02-28-2008, 10:41 PM - Thread Starter
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Quote:
Originally Posted by speco2003 View Post

This is just DUMB even as a DBT. It is completely a personal taste thing. Really you think it had a wide soundstage? I thought it sounded thin and harsh. What one person thinks is a wide stage may be someone elses worst sound.

And the test could never be repeatable. Why? Because the biggest variable, your ears, change daily and sometimes even by the hour. Based on your mood,the weather,stuffy head etc..

Just another buch of audiophile tomfoolery.

Here we go again. I doubt you even bothered to read my entire post. I'm sure you believe that this high-end audio thing is all about "gullible" audiophiles who are mislead my "snake oil" salesment and who succomb to the "placebo" effect. I seriously doubt you have ever listened to a truly transparent system. The only thing dumb is your ignorance.

Ignorance sure is blissful.

C N Machani
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post #11 of 98 Old 02-29-2008, 12:02 AM - Thread Starter
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Chu Gai, FMW,
I deliberately constructed my test to exclude the potential for perceptual bias and "placebo effect" as much as possible.

Now on the question of level matching, I have found that within a certain SPL band (medium to medium high) listening levels, the soundstage is "stable" for each CDP in that the dimensions or image positions do not change.

Let me elaborate further on my testing methodology:

1. I selected just two tracks of excellent CD recordings which have wide soundstage dimensions, instrument separation. I then performed a few test runs where I determined the specific "sonic cues" to listen for (for example, the image position of the announcer's voice in the Patricia Barber CD track, the sound of the "right most clapper" in the FIM Audiophile Reference CD track, and so on). I selected 12 of these "sonic cues" in total, the ones that had the most distinct and clear sonic images.

2. NOTE: In the test set-up runs itself, I found that the sonic images were very stable and varying the volume either up or down by around 15% did not change the position of the images. Thus it was clear to me that level matching was NOT necessary.

3. I made 12 copies of the test sheet, 4 for each player. In each run, I noted the position of the sonic images relative to my speakers, side and real walls. In the case where the image was of a voice or horn instrument, I noted the width.

4. Chu Gai, I am well aware that moving the listening position just a couple of inches left or right from the sweetspot changes the dimensions of the soundstage, so I used a marker to ensure that my head was in the sweetspot.

5. The listening tests were performed over two hours between 11pm - 1am in very quiet conditions. I observed that on repeat tests the soundstage dimensions and image positions in the soundstage were very consistent for each player.

While the differences in sounstage between the JVC and the Marantz were slight, the difference between the Marantz and the Onkyo were startling and, I repeat, consistent between runs.

Based on 2 and 5, I concluded that level matching has no bearing on soundstage when the speaker output volume is at medium to medium high levels. I believe I would most certainly get the same results if the volume pot was masked and someone else controlled the volume on the remote.

This is conclusive enough to me that CDPs can be differentiated by soundstage alone, especially if the CDPs are at different levels of quality. The Onkyo DX7555 is a considerable step up from the Marantz CC4300. Perceptual bias is not enough to explain the differences I am clearly hearing.

I suspect the reason the Onkyo stands apart is its ultra low clock jitter (+/- 1.5 ppm) and also, based on my understanding, its analog output stage uses a form of pulse width modulation (PWM) rather than traditional opamps. If it does indeed use PWM, it might explain its excellent time and phase accuracy and linear response.

C N Machani
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post #12 of 98 Old 02-29-2008, 12:41 AM
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Quote:
Originally Posted by machani View Post


Ignorance sure is blissful.



And you proved that be ignoring science and embrassing completely flase ideas.

Now if the "soundstage" is influenced by time and phase, (I have news for you phase is time so they are not seperate things. I suspect you confused phase and polarity) then it can be measured with SMAART very easy. I have listed to more "transparent" systems than you can count.


Thanks at least for taking the time to post the gear you used. It should be easy enough for me to test with some real science and post the results for you. I am out of town on a tour until 3-10 so I can get the gear then and test it.Should be fun to expose the hot air.
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post #13 of 98 Old 02-29-2008, 12:54 AM
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The Onkyo has a $4.79 DAC in it.

http://www.wolfsonmicro.com/products/price/WM8716/

Thats from the spec page on the Onkyo website.
http://www.onkyousa.com/model.cfm?m=...act%20Disc&p=f
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post #14 of 98 Old 02-29-2008, 07:09 AM
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Quote:
Originally Posted by machani View Post

Chu Gai, FMW,
I deliberately constructed my test to exclude the potential for perceptual bias and "placebo effect" as much as possible.

That's a good thing but you didn't exclude perceptual bias at all. In order to exclude it you need to do the comparative listening tests without knowing which unit you are hearing at a given time and the levels need to be perfectly matched. It is knowledge of the products themselves that causes the bias to enter the results. From my experience, your results are completely caused by placebo effect and not caused by the CD players themselves at all. Competently designed modern CD players have been proven to have no audible difference between each other in bias controlled tests so that's why a say what I say. I assume the units you are testing are working properly so there should be no audible difference at all. Not even a hint of it.

You need two people. One person substitutes the products and does the level matching (critical, by the way) in a manner in which the listener has no idea which unit is which. That is the only way to eliminate bias. As soon as you know what you are hearing, your biases take control when audible differences are either subtle or non existent. It happens to all of us. None of us are immune from it. The only difference is that we objectivists accept the facts and the reality and subjective audiophiles do not. The facts and the science apply to all of us nevertheless.
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post #15 of 98 Old 02-29-2008, 07:10 AM
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Machani, as far as I can tell from your post, those are still sighted tests where you know the identity of the player. Further, your post suggests that level matching was done (the particulars were not noted such as were test tones used or pink noise or...) by by an SPL meter. Certainly one wants a comfortable volume but matching between units ought to be done with a multimeter and test tones. Not doing that confounds matters. Also, the +/- 1.5 ppm does not refer to jitter but the accuracy of the clock. Jitter is another matter entirely.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #16 of 98 Old 02-29-2008, 07:17 AM
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Quote:
I deliberately constructed my test to exclude the potential for perceptual bias and "placebo effect" as much as possible.

Hah! No, you didn't do anything to exclude that possibility. Without a blind test, perceptual bias is inevitable. Here's an example:

Quote:
I observed that on repeat tests the soundstage dimensions and image positions in the soundstage were very consistent for each player.

Well, of course they were. Once you've heard them once, and developed an initial impression, that impression colors your subsequent trials. That's why you need to do this blind.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #17 of 98 Old 03-01-2008, 02:04 PM - Thread Starter
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Quote:
Originally Posted by speco2003 View Post

And you proved that be ignoring science and embrassing completely flase ideas.

Now if the "soundstage" is influenced by time and phase, (I have news for you phase is time so they are not seperate things. I suspect you confused phase and polarity) then it can be measured with SMAART very easy. I have listed to more "transparent" systems than you can count.


By timing I am referring to differntial timing. The ear can detect extremely minute time difference (in the order of a few microseconds). That is why it is important for a listening subject to be seated at the "sweetspot" of a stereo system, in order to get the "intended" soundstage that is present in the recording.

Phase accuracy is also necessary to properly determine both distance and directional cues.

C N Machani
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post #18 of 98 Old 03-01-2008, 02:08 PM
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I guess that settles it.
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post #19 of 98 Old 03-01-2008, 02:09 PM - Thread Starter
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Quote:
Originally Posted by Chu Gai View Post

Machani, as far as I can tell from your post, those are still sighted tests where you know the identity of the player. Further, your post suggests that level matching was done (the particulars were not noted such as were test tones used or pink noise or...) by by an SPL meter. Certainly one wants a comfortable volume but matching between units ought to be done with a multimeter and test tones. Not doing that confounds matters. Also, the +/- 1.5 ppm does not refer to jitter but the accuracy of the clock. Jitter is another matter entirely.

ChuGai,
I explained that I did not perform level matching, and why accurate level matching is not necessary for testing soundstage or imaging.

May I suggest you try this for yourself. Sit in the sweetspot of your stereo listening room. Play a recording which has a good soundstage and solid images. With the remote, adjust the volume up or down (+/- 15%) from medium-high listening levels. See if the soundstage or distance/directional cues of the images change. They should not.

On the jitter, I stand corrected. +/- 1.5 ppm refers to clock accuracy, not jitter performance.

C N Machani
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post #20 of 98 Old 03-01-2008, 02:36 PM
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Quote:
Originally Posted by machani View Post

ChuGai,
I explained that I did not perform level matching, and why accurate level matching is not necessary for testing soundstage or imaging.


The reason level matching and blind testing is critical is because it will show that there is no audible difference between the three CD players. I've tested scores of them. That's just the way it is. CD players do not and cannot generate or change a sound stage. The laws of physics prevent it. So continuing on with subjective tests and then explaining why you think they are valid isn't valid.
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post #21 of 98 Old 03-01-2008, 02:39 PM
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I explained that I did not perform level matching, and why accurate level matching is not necessary for testing soundstage or imaging.

Level-matching is absolutely required for any listening test. This is so basic as to be beyond debate in the field.

Quote:
May I suggest you try this for yourself. Sit in the sweetspot of your stereo listening room. Play a recording which has a good soundstage and solid images. With the remote, adjust the volume up or down (+/- 15%) from medium-high listening levels. See if the soundstage or distance/directional cues of the images change. They should not.

They may well not (much), but when you do a listening test, you can't just listen to soundstage, without being influenced by other aspects of the sound. That's why your little "experiment" doesn't demonstrate anything--you haven't controlled for the relevant variables.

Try it again our way: Match levels, and compare the players without seeing them. Listen to two at a time, and decide which one has the better soundstage. If you guess the same one every time, then you've demonstrated something. But I doubt you will.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #22 of 98 Old 03-01-2008, 02:43 PM
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Quote:
Originally Posted by machani View Post

By timing I am referring to differntial timing. The ear can detect extremely minute time difference (in the order of a few microseconds). That is why it is important for a listening subject to be seated at the "sweetspot" of a stereo system, in order to get the "intended" soundstage that is present in the recording.

Phase accuracy is also necessary to properly determine both distance and directional cues.

Uhhh wrong again. The ear detects changes atabout 20 miliseconds. 1 MS equals about a foot. Its called the HAAS effect,

http://www.rane.com/par-h.html

Please stop talking about things you have no clue about. The thread wass about DBT and you have not done that in the least.
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post #23 of 98 Old 03-02-2008, 01:13 AM
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Quote:
Originally Posted by machani View Post

ChuGai,
I explained that I did not perform level matching, and why accurate level matching is not necessary for testing soundstage or imaging.


Not correct. Why don't you listen?

Sound and video is not magic, it is pure physics. Physics that can be magical
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post #24 of 98 Old 03-02-2008, 08:24 AM
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If you insist it's not necessary then why not just do it? Shouldn't hurt right?

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #25 of 98 Old 03-02-2008, 02:08 PM
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Quote:
Originally Posted by machani View Post

... The ear can detect extremely minute time difference (in the order of a few microseconds). That is why it is important for a listening subject to be seated at the "sweetspot" of a stereo system, in order to get the "intended" soundstage that is present in the recording.
.

Yes, it can under very special circumstances, like headphones, and special signals. It has not been tested with music and speakers. And, based on other tests, such as JND threshold, distortion, etc testing. The more complex the signal, like music, the higher the thresholds become, way higher. So, your microseconds may increase to 10s or 100s.
But, in any event, the reliability of your protocol is very poor.
Besides what was pointed out by others, level matching and DBT, you need to involve statistics for a significant outcome. Also, how do you know your head was in the exact same location in space? 4" can be moved almost without you realizing it, especially after you leave your sitting position to change components, etc.
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post #26 of 98 Old 03-02-2008, 10:35 PM - Thread Starter
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Quote:
Originally Posted by speco2003 View Post

Uhhh wrong again. The ear detects changes atabout 20 miliseconds. 1 MS equals about a foot. Its called the HAAS effect,

http://www.rane.com/par-h.html

Please stop talking about things you have no clue about. The thread wass about DBT and you have not done that in the least.

It's you who's confused!
I quote from the same source:
"The Haas Effect tells us that humans localize a sound source based upon the first arriving sound, if the subsequent arrivals are within 25-35 milliseconds. If the later arrivals are longer than this, then two distinct sounds are heard. "

Note the keyword within. The brain can perceive differential timing (the scientific term is interaural time difference) as low as 10 microseconds. So the range is from about 10 microseconds to 30 milliseconds in order for the ear to localize the sound source.

Here are some references:
On sound localization:
http://en.wikipedia.org/wiki/Sound_localization

On Interaural Time Difference (ITD)
http://en.wikipedia.org/wiki/Interaural_time_difference
Quote: "The normal human threshold for detection of an ITD is up to a time difference of 10μs (microseconds). "

Here is an excellent thesis on the subject of spatial sound from the Helsinki University of Technology:
http://lib.tkk.fi/Diss/2007/isbn9789...9512290512.pdf
Quote: "This mechanism is in great demand, as the ITD processing requires far better resolution (10-20 μs) than any other neural process [57]."

I suggest you stop pretending to be an authority when you are just a plain BS'er!

C N Machani
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post #27 of 98 Old 03-02-2008, 10:40 PM - Thread Starter
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Chu Gai, FMW, PULLIAMM, et al,
A couple of questions for you all:

1. Have you ever conducted a test, DBT or sighted, specifically to check for soundstage?

2. Is your two channel system capable of producing a 3D holographic soundstage, where your speakers completely "disappear", and does it have enough instrument separation that all you hear a are the sounds of the vocalists and instruments coming from distinct parts of the soundstage?

If your answer is "No" to either of these questions, then I can only conclude that you have insufficient experience to respond in any constructive way.

If your answer is "Yes" then I would appreciate if you would elaborate on your findings.

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post #28 of 98 Old 03-03-2008, 04:44 AM
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1. I've done DBT's for the purposes of listening for differences. They were all level matched. I can't stress that importance enough.
2. I'm quite satisfied with my speakers and would've considered 'changing' them had I had the balls and the foresight to have bet $100 on the Giants during the entire playoffs based on what's known as the Money Line. That means, taking the winnings plus the investment and rebetting it on the total of the four playoff games. That would've netted me about 33K.

Your findings suggest you may be having room issues such as comb filtering which was described by Ethan Weiner, both here and I believe on his website. Referring to the articles which you listed would suggest that one must have their head locked firmly in a vice or between the thighs of a dominatrix in order not inadvertently introduce such ITD's. Do you hear the difference if a violin or clarinet player moves their instrument around when playing?

Regarding soundstage and all that, I have a link to a paper, actually a patent, by the late John Dunlavy on a method to optimize this using relatively available means. If you're interested, I'll dig up the link and post it. Otherwise, it's probably in the archives somewhere.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #29 of 98 Old 03-03-2008, 05:10 AM
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Quote:
Originally Posted by machani View Post

Chu Gai, FMW, PULLIAMM, et al,
A couple of questions for you all:

1. Have you ever conducted a test, DBT or sighted, specifically to check for soundstage?

2. Is your two channel system capable of producing a 3D holographic soundstage, where your speakers completely "disappear", and does it have enough instrument separation that all you hear a are the sounds of the vocalists and instruments coming from distinct parts of the soundstage?

If your answer is "No" to either of these questions, then I can only conclude that you have insufficient experience to respond in any constructive way.

If your answer is "Yes" then I would appreciate if you would elaborate on your findings.

No, these tests are conducted only to determine if there is an audible difference at all. The cause of the difference isn't the reason for the test. Have you ever conducted a bias controlled listening test of any kind? If not "then I can only conclude that you have insufficient experience to respond in a constructive way."

Go do the tests. Then criticize all you like.
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post #30 of 98 Old 03-03-2008, 05:53 AM
 
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Quote:
Originally Posted by machani View Post

2. Is your two channel system capable of producing a 3D holographic soundstage, where your speakers completely "disappear", and does it have enough instrument separation that all you hear a are the sounds of the vocalists and instruments coming from distinct parts of the soundstage?

Yes.
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