Please Judge My A/B Methodology, Mtry Others

[magictooth]

Well, I convinced the wife to help me out one more time to do some A/B comparisons between CD players. She's not going to do 45 trials this time, so I can't say how many tests I'm going to do, but I hope it'll be at least 10-15.

Here's the methodology. Please critique and add any ideas that you might think would help.

I've got two identical CDs. One is going to be loaded into the Toshiba SD-1600, the other into the Classe DVD/CD-1. The prices are $200 (probably worth $20 now) and $3500 (worth $1300-1500 now) respectively. They're both hooked up to my Audiomat Integrated amp with exactly the same type of IC. One is going into line 4, the other line 5.

Both CDs will be playing at the same time, but the input selector will be changed (or maybe not), and I'll try to identify which DVD player is playing. In between the changing input, the mute switch is going to be clicked, and she's going to change the volume knob at random. This way there's no volume differences to be able to key off of. When she's changing the input, I'll have my eyes closed with my hands over my ears so I can't hear any click - although there's virtually no noise if she turns the properly anyways.

I'm going to cover the displays of each unit so I can't see if there's a discrepancy between the playing times of each CD.

Is there anything else you'd like to add to this method, mtry?

[996turbo]

The volume changes will make it kinda hard.
We usually try to level match that way you are not being confused by the volume changes. I am interested to hear what you think as some others think there will be no difference. Post your findings for us.

[magictooth]

The volume changes will make it kinda hard.
We usually try to level match that way you are not being confused by the volume changes. I am interested to hear what you think as some others think there will be no difference. Post your findings for us.
I'm trying to make it harder to A/B.

[996turbo]

I understand. You want to show that regardless of the volume you will be able to tell the players apart.
I personally do not think a test is even needed for that. I have challenged Mytrcraft and the others to a challenge but they are obviously afraid to respond.

Good luck with your test and please inform us of the results.

[jeskibuff]

I'm trying to make it harder to A/B.You actually want to make it EASIER to A/B. Throwing the volume level changes into the mix will just make it more confusing. Make sure you've got the input gains matched so the volumes are as close to each other as possible, as the players most certainly will have differing output levels. Forget the muting, too. Just have your wife cough when she makes the switch (or PRETENDS to make the switch).

The timing will be your toughest trick, but quick jabs at the pause button on the unit that's slightly ahead in time will help to get both units synchronized.

[magictooth]

You actually want to make it EASIER to A/B. Throwing the volume level changes into the mix will just make it more confusing. Make sure you've got the input gains matched so the volumes are as close to each other as possible, as the players most certainly will have differing output levels. Forget the muting, too. Just have your wife cough when she makes the switch (or PRETENDS to make the switch).

The timing will be your toughest trick, but quick jabs at the pause button on the unit that's slightly ahead in time will help to get both units synchronized.
I don't have any voltage adjustments available to me. We can't really match the volumes because the switch on the amp is just a knob - no numbers or graduation markers. I think there is about a 4-5 dB difference when you play a tone and measure with the SPL. I don't want to have any volume difference bias in this experiment hence, the variable volume.

About the mute switch, both discs are identical discs with a variety of music. They should be fairly easy to synchronize. Just hit play and then pause, and then play once we're set to go. The mute will allow us to have an interval to allow for the seamless switching or pretend switching to go off without a hitch.

[mtrycraft]

I don't have any voltage adjustments available to me. We can't really match the volumes because the switch on the amp is just a knob - no numbers or graduation markers. I think there is about a 4-5 dB difference when you play a tone and measure with the SPL. I don't want to have any volume difference bias in this experiment hence, the variable volume.


STOP right there.!!!!
If you cannot match levels to 0.1dB spl at several frequency bands, your test is flawed before strating.

If you cannot synchronize the two CD palers to withing a few milli seconds of time which you cannot, it is flawed.

Best if you play one song on one player and the same song on the next player as that is all you can do. But, without level matching, forget it.


About the mute switch, both discs are identical discs with a variety of music. They should be fairly easy to synchronize.

To a few milli seconds? If not, you can tell one from th eother just from the time delay.
Back to square one.

[996turbo]

Miliseconds?

.1 dB

What the hell

[FLZapped]

Miliseconds?

.1 dB

What the hell

Yep, those nasty JNDs again. . . . -Bruce

[magictooth]

STOP right there.!!!!
If you cannot match levels to 0.1dB spl at several frequency bands, your test is flawed before strating.

If you cannot synchronize the two CD palers to withing a few milli seconds of time which you cannot, it is flawed.

Best if you play one song on one player and the same song on the next player as that is all you can do. But, without level matching, forget it.

To a few milli seconds? If not, you can tell one from th eother just from the time delay.
Back to square one.

I want some help designing a good A/B test with the equipment that I've got. I think that I've got a good methodology. Please indicate to me why a random volume change would make it easy to identify each CDP. If the master volume changes by up to +/- 15dB after each sample how will that be a key? I stress that the volume change will be random or possibly none at all. I won't have any idea about it.

About the synchronization to milliseconds, that is going a bit overboard. The mute switch will be clicked for between 5-10 seconds so any differences in synchronization of milliseconds, centiseconds, or deciseconds will be lost in the silent times. I'm going to have the displays covered so I can't see the times on the units either. For the start of the discs, I'm going to hit play, then back, then I'll pause both units, hopefully at right around the same time. I'm sure that I'll be able to get less than a 0.25 second discrepancy in the units. With the displays covered and a very long interval between samples, will that be sufficient to nullify any time discrepancy issues?

As an aside, I remember you writing that acoustic memory is just seconds at most. What exactly do you mean by that?

[996turbo]

The problem magictooth is that any test you devise if it comes out contrary to Mytrs beliefs will be criticized. The whole millisecond thing is proof. I have repetedly asked these people to participate in a test. They refuse because they have no experience with the gear I will be testing and do not know if their beliefs will stand up against a test. The only thing they can do is sit in their blind and shoot down things they are not willing to step up to the plate and participate in. They have proven that the only thing they can do is spit out things they have read. You are wasting your time asking him how to do the test. You could do it exactly as he states and he will find some unarguable bull to discredit your work.

[996turbo]

Mytr is somewhat correct in his length of Auditory memory as it is a subset of sensory memory. The problem is that things can and do move from sensory to short term (stm) to Long term memory (ltm).

[Resident Loser]

...you MUST remove all variables from the equation to even things out...

With re: to volume, the louder unit will always seem to sound better. This would skew the results of a one-on-one," which is better?" scenario...adding volume shifts for tests of your intent, which, if I read you correctly, is simply identifying units, it would seem to cloud the issue entirely...

As is true with "sync"ing, however, while one would think muting should mask the some potential identifiers, it has problems of it's own. Short term memory, especially regarding audio, is easily confused, thwarted, misled(I can't quite choose a simple term, so pardon me and I hope you get my drift)...long intervals between samples will only exacerbate this.

Everything should be seamless and strict protocols must be followed for any results to be meaningful...and of course, to stand up to the strictest of scrutinies, they should be repeatable.

jimHJJ(...BTW, ignore the noises you may hear from the duck-hunting, ball player...)

[magictooth]

...you MUST remove all variables from the equation to even things out...

With re: to volume, the louder unit will always seem to sound better. This would skew the results of a one-on-one," which is better?" scenario...adding volume shifts for tests of your intent, which, if I read you correctly, is simply identifying units, it would seem to cloud the issue entirely...

As is true with "sync"ing, however, while one would think muting should mask the some potential identifiers, it has problems of it's own. Short term memory, especially regarding audio, is easily confused, thwarted, misled(I can't quite choose a simple term, so pardon me and I hope you get my drift)...long intervals between samples will only exacerbate this.

Everything should be seamless and strict protocols must be followed for any results to be meaningful...and of course, to stand up to the strictest of scrutinies, they should be repeatable.

jimHJJ(...BTW, ignore the noises you may hear from the duck-hunting, ball player...)
I did an A/B where the difference between units was about 2dB. The louder unit being the the above mentioned Toshiba SD 1600. I scored 15/15 in telling which one I like better even though the cheapo one was louder. IMO, that debunks all the sayings that louder=better.

With regards to the sync issue, I can press the pause button at exactly the same time, and play once again at the same time, but there may be internal player issues such as how long the delay is for the commands to be executed, etc. That's why the delay in between.

Basically what I'm trying to do is to make it MORE DIFFICULT to tell the differences between players. If I'm reading you correctly, you are also saying that it will become more difficult to tell between players given my above listed protocols. Please correct me if I'm wrong.

Also let me clarify the hypothesis: Many people on this board believe that there are NO sonic differences AT ALL between any DVD player. I want to prove or disprove this idea with an A/B comparison with the equipment and manpower that I have available. I know that I can't accurately level match the 2 units, hence the possible variation of master volume. I realize that I may not be able to sync the units to a couple milliseconds (although I should get very close certainly less than .0.25 sec), hence the longer delay.

The music on both discs comes from a variety of sources. Thank goodness for CDRs. There are selections from 6 different discs, and the music from each disc plays at different volume levels so that even if I had a voltage attenuator, I wouldn't be able to match the output voltage in both machines so that the volume in dBs is exactly equal.

[Resident Loser]

"...Mytr is somewhat correct in his length of Auditory memory as it is a subset of sensory memory. The problem is that things can and do move from sensory to short term (stm) to Long term memory (ltm)..."

...that seem to lend credence to all the "ex-spurts" regardless of what they "spurt" about...

Whether iconic, echoic or hapatic, sensory memory IS passed to short term memory which then uses it for temporary recall of the information under process. However, short term memory decays in roughly 200ms. and has a finite capacity. Information is transferred to long term memory only by constant exposure to a stimulus or information. This is a process that happens over time and would seem render it incompatible, in fact being at odds, with the type of testing we are speaking of.

You may recall the words, the melody and possibly salient characteristics of a specific performance(perhaps a misplaced note or the "sound" of an instrumental solo) but these are memories we aquire via repetition, over time...

jimHJJ(...now please be quiet, the adults are engaged in civil conversation...)

[Resident Loser]

...hypothesis is flawed at the outset...CDPs, DVDPs, wires and cables, in fact, any component you care to test, can sound "different". The trick(and the source of all the unrest)is to consistently identify the units being compared under DBT conditions and result in an outcome that is statistically relevant.

"...That's why the delay in between..."

Here's where the auditory memory comes in...see my response to Porsche-boy...

"...Basically what I'm trying to do is to make it MORE DIFFICULT to tell the differences between players..."

Beginning with sources of varying qualities(loudness, etc.) giving you no baseline reference whatsoever, "more difficult" seems an understatement...

jimHJJ(...I'm sorry, it just seems to make no sense...)

[996turbo]

I have attempted to engage in meaningful dialogue with you but you insist on making little snide comments. If you are the adult you are I would suggest that you stop being such an a$$hole. You people criticize people on spelling or navigating this site. That is childish. Here is a bit of psychology for you. Which defense mechanism is used when a person belittles another?

[Resident Loser]

..are you referring to?

jimHJJ(...if ya can't stand the heat...)

[996turbo]

jimHJJ(...now please be quiet, the adults are engaged in civil conversation...)

jimHJJ(...if ya can't stand the heat...)

I guess you stm is as good as your hearing

[Resident Loser]

...that your misuse of vocabulary is indicative of your perceptive abilities...

Where in those two statements was I:

False, deceptive, dishonest or insinuating?

Your entire demeanor and attempt at insult is sophomoric, hence the "adult" reference...merely stating the obvious...

The "heat" phrase is quite simple...you seem to have no problem with dishing it out, but when the shoe is on the other foot...? You think nothing of casting aspersions on myself, Skeptic, woodman and of course, Mtry...and further you applaud posts by those whose only claim to fame seems to have been the reading of "101 Ways To Use the Word @$$"...your support indicates tacit agreement and thus complimentary induction to the "Birds of a Feather" club with all of it's perks...

If anything I've been quite blatant and overt! I reserve snide and sarcastic remarks for those whom I think can appreciate such subtleties...

jimHJJ(...and that ain't you!...hmmm...is that snide?...nah! Just an insult...)

[WmAx]

I have attempted to engage in meaningful dialogue with you but you insist on making little snide comments. If you are the adult you are I would suggest that you stop being such an a$$hole. You people criticize people on spelling or navigating this site. That is childish. Here is a bit of psychology for you. Which defense mechanism is used when a person belittles another?
Is this the same 996turbo who started the 'mtrycrafts is an idiot thread', which has the sole purpose of belittling someone in a childish manner? Is the irony not apparent?

LMFAO

-Chris

[996turbo]

Is this the same 996turbo who started the 'mtrycrafts is an idiot thread', which has the sole purpose of belittling someone in a childish manner? Is the irony not apparent?

LMFAO

-Chris
The purpose was to point out that alot of us think there are differences in equipment. I suggest you read the post and not get cought up in the title. You will notice that in the meat of the thread I did say that I did not think he was an idiot I just disagreed with his position.

[WmAx]

The purpose was to point out that alot of us think there are differences in equipment. I suggest you read the post and not get cought up in the title. I suggest you take the time to think about what you doing. Your point is made very poorly.


You will notice that in the meat of the thread I did say that I did not think he was an idiot Hmmm. Ok.

996turbo, you know what you are? Let me give you a clue........

YOU STUPID MORON. You REALLLLLLLLY STUPID MORON. Your really a STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID STUPID MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON MORON.

STUPID MORON!

http://www.linaeum.com/images/meatpost.jpg

Oh, sorry. I did not mean anything at the beginning. Just look in the meat of the post. In case you can not see the picture I posted, in the center of the meat it says: "996turbo is NOT really a stupid moron, you just have to look in the meat of the post. :-P"

-Chris

[996turbo]

What did I do to you personally for you to be such an ass. It is it in your nature? If so I will understand. I do agree that this thread and others has gotten out of control. I think if you look at all the post yours are just as vitriolic as others.When you say that my demeanor is sophmoric I suggest you look at yourself and judge others only after you have looked inward.

I apolagize if I have offended anybody. It honestly was not my intention. I just completely disagree with Mtry and some of the others. He has opened himself to criticism as have others here (including myself) by openly displaying our opinions. We are all in the hobby called audio. I would think that we all have a common passion. There are so few of us that I would think this childish banter could end. I for one am ending it here. I will no longer respond to nor post any defamatory personal post.

I would think that if you are the adult that you portend to be that you can do the same.

[Resident Loser]

jimHJJ(...subtle it ain't...)

[996turbo]

I know I said I would not reply to openly antagonistic post but this one was done while I was writing mine.

LOL that is pretty good. I especially like the piece of meat.

Once again very funny stuff.

[WmAx]

What did I do to you personally for you to be such an ass. It is it in your nature? If so I will understand. I do agree that this thread and others has gotten out of control. I think if you look at all the post yours are just as vitriolic as others.When you say that my demeanor is sophmoric I suggest you look at yourself and judge others only after you have looked inward.This is called "Feeding you your own medicine.". Sure, it's an exaggeration, but it's exactly what you did. Don't like it, it seems......

Lesson learned?

-Chris

[996turbo]

Calm down Chris,


I really did think the meat thing was funny though.

[996turbo]

I see you Live in Virginia perhaps Mtry and the others would trust you to do the test with different equipment. I think it would be a very interesting experience for all involved. I live in NC which may be as little as an hour or two away from you.

[Resident Loser]

...like calling me an @$$ho!e in a previous post or...

"...What did I do to you personally for you to be such an ass..."

Clever question...it contains it's own answer...

"...I think if you look at all the post yours are just as vitriolic as others..."

"... When you say that my demeanor is sophmoric I suggest you look at yourself and judge others only after you have looked inward..."

As I recall, you have voiced your opinions as though they were facts...each one has been met with reasonable and factual responses in a civilized manner...instead of countering with logical, legitimate responses, you simply took the low road, I know you did, you know you did, as do all the witnesses to your posts.

"...I just completely disagree with Mtry and some of the others..."

As is your right, so far, so good...

"...He has opened himself to criticism as have others here (including myself) by openly displaying our opinions...."

When did that(displaying his opinion) occur? Again, you posted opinions as facts and it was pointed out that certain biases can skew subjective listening "tests", certain protocols MUST be followed for any results to be viable, that sort of thing. In fairly typical manner you responded, not with any sort of logical debate but rather with the "Sez you" attitude...trust me, we have seen this all before and know how the script reads...THAT'S experience.

"...I would think that if you are the adult that you portend to be that you can do the same..."

Sorry, can't resist, did you mean "pretend to be"? Portend is a whole 'nother animal...

jimHJJ(...have fun and enjoy the music...)

[Pat D]

I did an A/B where the difference between units was about 2dB. The louder unit being the the above mentioned Toshiba SD 1600. I scored 15/15 in telling which one I like better even though the cheapo one was louder. IMO, that debunks all the sayings that louder=better.

With regards to the sync issue, I can press the pause button at exactly the same time, and play once again at the same time, but there may be internal player issues such as how long the delay is for the commands to be executed, etc. That's why the delay in between.

Basically what I'm trying to do is to make it MORE DIFFICULT to tell the differences between players. If I'm reading you correctly, you are also saying that it will become more difficult to tell between players given my above listed protocols. Please correct me if I'm wrong.

Also let me clarify the hypothesis: Many people on this board believe that there are NO sonic differences AT ALL between any DVD player. I want to prove or disprove this idea with an A/B comparison with the equipment and manpower that I have available. I know that I can't accurately level match the 2 units, hence the possible variation of master volume. I realize that I may not be able to sync the units to a couple milliseconds (although I should get very close certainly less than .0.25 sec), hence the longer delay.

The music on both discs comes from a variety of sources. Thank goodness for CDRs. There are selections from 6 different discs, and the music from each disc plays at different volume levels so that even if I had a voltage attenuator, I wouldn't be able to match the output voltage in both machines so that the volume in dBs is exactly equal.
Well, I have to agree that sometimes a little softer sounds better, but it's a very minor point and does nothing to validate your test procedures.

The fact that proving that players sound different by using a listening test can be difficult and cumbersome, although those who have an ABX machine available can do so without assistance. The can level match the two inputs (preferably with a voltmeter), it switches quickly and silently, and it will randomly pick what "X" is and keep a record of it for you (if I understand it all correctly).

Anyway, with your method, the presumption would be that the differences heard are overwhelmingly likely to be due to level differences. Even if you did an enormous number of comparisons and came up with a statistically significant result, it is quite likely that there was some bias in setting the levels. So, sorry, level matching is the only way to go for such auditions. If you use two preamps, feeding one into the other, it is relatively easy to match the levels, but this may introduce other sources of error, such as perhaps a ground loop, which could affect the outcome.

Of course, you could simply measure the FR and see if both players are flat enough to be within the JNDs. If not, one could assume there is likely an audible difference, at least under some conditions (and listening to music might not be one of them!). Not every CDP has a flat FR (for example, some Walkman type players meant for use with small headphones have a significant bass boost! But then, that's designed not to sound the same). There are a number of other possibilities, but there is no reason to expect them to apply with decent equipment. No one holds any variety of "everything sounds the same," certainly no one around here.

[996turbo]

Enough is enough.

A liberal and a conservative could go on forever arguing their beliefs.

I know I have heard differences just as you know there is none to be heard.

I will leave this topic (not the site) as it well never be resolved in this forum.

I guess it is the old disagree to disagree.

Jason
Enjoy the music!

[mtrycraft]

Miliseconds?

.1 dB

What the hell


I told you need to do some outside research, didn't I? That is where you should spend your spare time on, real audio data that is out there, and human psychology.

[mtrycraft]

The problem magictooth is that any test you devise if it comes out contrary to Mytrs beliefs will be criticized. The whole millisecond thing is proof. I have repetedly asked these people to participate in a test. They refuse because they have no experience with the gear I will be testing and do not know if their beliefs will stand up against a test. The only thing they can do is sit in their blind and shoot down things they are not willing to step up to the plate and participate in. They have proven that the only thing they can do is spit out things they have read. You are wasting your time asking him how to do the test. You could do it exactly as he states and he will find some unarguable bull to discredit your work.


My beliefs? Hardly. It is what the audio research dictates.

[mtrycraft]

I did an A/B where the difference between units was about 2dB. The louder unit being the the above mentioned Toshiba SD 1600. I scored 15/15 in telling which one I like better even though the cheapo one was louder. IMO, that debunks all the sayings that louder=better.

Of coursze you preferred one better. There was a 2dB level difference and were able to isolate it and know in fact which unit was louder. You think your bias is not at work? Oh, your bias is hidden from your consciousness so you have no control of it. Like gravity. It is.
Unfortunately in a proper protocol, it has to be level matched, 0period, end of story.

With regards to the sync issue, I can press the pause button at exactly the same time, and play once again at the same time, but there may be internal player issues such as how long the delay is for the commands to be executed, etc. That's why the delay in between.

Yep, all these giove clues which component is in play and easy to guess and make selections.

Basically what I'm trying to do is to make it MORE DIFFICULT to tell the differences between players. If I'm reading you correctly, you are also saying that it will become more difficult to tell between players given my above listed protocols. Please correct me if I'm wrong.

No, the idea is to be fair, eliminate clues to identify differences for known reasons, and do it without your knowledge of which player is playing and differentiate by sound alone.


Also let me clarify the hypothesis: Many people on this board believe that there are NO sonic differences AT ALL between any DVD player.


Any player? Where do you get that idea from? Please don't make things up. Bad enough when people imagine things.

I want to prove or disprove this idea with an A/B comparison with the equipment and manpower that I have available. I know that I can't accurately level match the 2 units, hence the possible variation of master volume. I realize that I may not be able to sync the units to a couple milliseconds (although I should get very close certainly less than .0.25 sec), hence the longer delay.

If you cannot level match, you cannot compare. Sync issue can be overcome. Just play a short segment on one player, then the same segement on another player but your memory will suffer.

so that even if I had a voltage attenuator, I wouldn't be able to match the output voltage in both machines so that the volume in dBs is exactly equal.

I think you are confused by now on this issue.
The two CD players have to play a test CD at the same level, to .1dB. The music on the two Cd must be identical in level, not that one track is louder but that both CD play each song equally loud.

[magictooth]

LOL - the inconsistencies that you get if you don't check the site for 5 days...

From Resident Loser:
With re: to volume, the louder unit will always seem to sound better.

PatD:
Well, I have to agree that sometimes a little softer sounds better

Who to believe?

[magictooth]

I did an A/B where the difference between units was about 2dB. The louder unit being the the above mentioned Toshiba SD 1600. I scored 15/15 in telling which one I like better even though the cheapo one was louder. IMO, that debunks all the sayings that louder=better.

Of coursze you preferred one better. There was a 2dB level difference and were able to isolate it and know in fact which unit was louder. You think your bias is not at work? Oh, your bias is hidden from your consciousness so you have no control of it. Like gravity. It is.
Unfortunately in a proper protocol, it has to be level matched, 0period, end of story.

With regards to the sync issue, I can press the pause button at exactly the same time, and play once again at the same time, but there may be internal player issues such as how long the delay is for the commands to be executed, etc. That's why the delay in between.

Yep, all these giove clues which component is in play and easy to guess and make selections.

Basically what I'm trying to do is to make it MORE DIFFICULT to tell the differences between players. If I'm reading you correctly, you are also saying that it will become more difficult to tell between players given my above listed protocols. Please correct me if I'm wrong.

No, the idea is to be fair, eliminate clues to identify differences for known reasons, and do it without your knowledge of which player is playing and differentiate by sound alone.


Also let me clarify the hypothesis: Many people on this board believe that there are NO sonic differences AT ALL between any DVD player.


Any player? Where do you get that idea from? Please don't make things up. Bad enough when people imagine things.

I want to prove or disprove this idea with an A/B comparison with the equipment and manpower that I have available. I know that I can't accurately level match the 2 units, hence the possible variation of master volume. I realize that I may not be able to sync the units to a couple milliseconds (although I should get very close certainly less than .0.25 sec), hence the longer delay.

If you cannot level match, you cannot compare. Sync issue can be overcome. Just play a short segment on one player, then the same segement on another player but your memory will suffer.

so that even if I had a voltage attenuator, I wouldn't be able to match the output voltage in both machines so that the volume in dBs is exactly equal.

I think you are confused by now on this issue.
The two CD players have to play a test CD at the same level, to .1dB. The music on the two Cd must be identical in level, not that one track is louder but that both CD play each song equally loud.

Wow, an in depth and interesting answer.

You say that the level differences are what I'm keying off of. I am trying to eliminate that bias with the equipment that I have available to me. I don't see how there could be any bias at all if the volume control gets changed unsighted (by my wife) and at random between tests.

As for the sync issue, you are most likely not a musician. I am proposing a 10-15 second delay between playing each segment. With no audible cues, how can a less than 0.25 difference in synchronization play any role identifying which one is playing first. To be able to count rests for a random interval of 10-15 seconds without any audible or visual cue is impossible. Not even improbable - impossible. Consider this: if you told the symphony to start the second movement 3 full bars of silence after the end of the first movement, but that nobody could direct and nobody could do any kind of head movement, etc., you'd have 100 musicians playing at slightly different times. I seriously don't believe that my method will lend any bias.

So Mtry, are you trying to say that you DON'T believe that all players sound the same? I realize that you have often said that all well designed players sound the same, but the difference between saying "well designed" and all players is a very obscure bit of minutiae. Please for the record state what you believe about DVD players playing RBCD. Unless I'm mistaken, I believe that you constantly denigrate spending over a very modest amount of money on a DVD player (or CDP). Please specify how much money is too much money for a well designed player.

With regards to the voltage attenuation, I was thinking of something else, namely the analog knob that I have which would increase the volume by differing amounts based ont he material you play. You are correct that I was making an incorrect statment.

[magictooth]

http://www.linaeum.com/images/meatpost.jpg

-Chris
ROFLMAO - I love it!!

[Resident Loser]

and circumstance...when comparing two units, and as a disinterested third party, I believe most people will gravitate towards a slightly louder signal as their preference...generally speaking...and you'll have to take distortion levels into account(even at lower levels some folks are quite sensitive to that), I'm not referring to a tremendous difference here, only a slight one...after all there are the old Fletcher-Munson curves and loudness compensation in general. Even tho' that is band-specific, I believe it tends to support my contention to some degree...Personal preference aside(and I do agree with Pat in my own listening habits)...but, if volume don't count to a part the general population, why the he!! am I constantly annoyed by them d@mned rolling boom-boxes?

jimHJJ(...and BTW "inconsistencies" would only apply if one of us had said both things...)

[magictooth]

and circumstance...when comparing two units, and as a disinterested third party, I believe most people will gravitate towards a slightly louder signal as their preference...generally speaking...and you'll have to take distortion levels into account(even at lower levels some folks are quite sensitive to that), I'm not referring to a tremendous difference here, only a slight one...after all there are the old Fletcher-Munson curves and loudness compensation in general. Even tho' that is band-specific, I believe it tends to support my contention to some degree...Personal preference aside(and I do agree with Pat in my own listening habits)...but, if volume don't count to a part the general population, why the he!! am I constantly annoyed by them d@mned rolling boom-boxes?

jimHJJ(...and BTW "inconsistencies" would only apply if one of us had said both things...)
No, the implication was inconsistencies between responses of various posters. It's funny like how some axioms are antithetical: "look before you leap" and "he who hesistates is lost" Same here for audio. I thought it was funny about inconsistent advice from the general AR populace regarding volume levels and liking unit.

[996turbo]

The inconsistencies he is refering to is two different opinions. Thatis the problem here.

[Resident Loser]

...Do we speak in one unified voice?

No. But, your use of the word without further qualification indicates that you think we are or should be..or at least THAT is what you infer...

The GCD(Great Cable Debate) is not a product of "inconsistency"(although some posters do, at times, seem to be talking out of both sides of their faces - in that case it would apply)...two different camps(as it were) with two very specific philosophies. Who to believe?

Would you use the word "inconsistency" with regard to public opinion re: Iraq? or the President? or Palestine? or any other issue that confronts us? I think not! Well perhaps some would, but they would be wrong to do so.

The public holds opinions that are diverse, differing, multifarious and manifold(to name a few)...

Same at this site, after all, it is somewhat of a microcosm...one might use the phrase "difference of" or "multitude of" or even "panoply of" opinions, as there are certainly any number of them...but they are not "inconsistent" with any one thing, by any measure; that is the key...it's one he!! of an indictment of this country's educational system if you can't see that not-so-subtle distinction...

jimHJJ(...now if the Dems nominated George Bush as THEIR candidate, THAT would be "inconsistent"...)

[Resident Loser]

...with anything...it is TWO DIFFERENT OPINIONS from TWO DIFFERENT PEOPLE...

jimHJJ(...Gott in Himmel...)

[996turbo]

You like to argue about everything.

How about this statement.

The opinions on this website are inconsistent.
The fact that we are talking about something outside of philosophy and within the realms of electronics makes it even more interesting.

Displaying or marked by a lack of consistency, especially:
Not regular or predictable; erratic: inconsistent behavior.
Lacking in correct logical relation; contradictory: inconsistent statements.
Not in agreement or harmony; incompatible: an intersection inconsistent with the road map.

I think the word perfectly describes this site.

[magictooth]

...with anything...it is TWO DIFFERENT OPINIONS from TWO DIFFERENT PEOPLE...

jimHJJ(...Gott in Himmel...)
C'mon, this is like making a mountain out of a molehill, but www.dictionary.com has inconsistency as
Displaying or marked by a lack of consistency, especially:
1.Not regular or predictable; erratic: inconsistent behavior.
2.Lacking in correct logical relation; contradictory: inconsistent statements.
3.Not in agreement or harmony; incompatible: an intersection inconsistent with the road map.

I wasn't saying that you were inconsistent, but rather that some of the information and statements made on this board by various members are inconsistent with each other. You would think that an axiomatic statement such as "louder always sounds better" would not have its corollary in "sometimes I find softer to sound better." I just thought that the differences were funny enough to make note of them.

[996turbo]

Little slow on your internet work there Magictooth. :)

I hope I do not fail the school system in this country when I say I knew what you meant immedietly.

[Resident Loser]

"...You like to argue about everything..."

Only when I'm right...

"...The opinions on this website are inconsistent..."

Inconsistent with what? Ethics? Religious dogma? The teachings of Chairman Mao? The Joy Of Cooking? There is no goal, no uniformity, no direction, no specific philosophy to kowtow to...no party line...

"...The fact that we are talking about something outside of philosophy and within the realms of electronics makes it even more interesting..."

Electronics!!! It's friggin' vocabulary and usage...LOOK, quick...over by the trees...It's a forest!!!

"...Displaying or marked by a lack of consistency, especially:
Not regular or predictable; erratic: inconsistent behavior.
Lacking in correct logical relation; contradictory: inconsistent statements.
Not in agreement or harmony; incompatible: an intersection inconsistent with the road map...I think the word perfectly describes this site..."

My choice would be: democratic with a soupcon of anarchy....did you read my reply to the toothsome one?

If "consistency"(or at least YOUR definition of it) is what you want, why not head on over to AA they'll tell ya' just what you want to hear...

jimHJJ(...anybody seen that big, brown bag of "IT"...)

[Resident Loser]

...you opted to conveniently ignore the body of my post and take issue with my comments on your word usage...

"...C'mon, this is like making a mountain out of a molehill, but www.dictionary.com has inconsistency as
Displaying or marked by a lack of consistency, especially:
1.Not regular or predictable; erratic: inconsistent behavior.
2.Lacking in correct logical relation; contradictory: inconsistent statements.
3.Not in agreement or harmony; incompatible: an intersection inconsistent with the road map..."

Foist, the above definition is for "inconsistent"...the word you incorrectly used was "inconsistencies"...the former an adjective, the latter a noun. At that very same site:

in-con-sis-ten-cy

American Heritage

1. The state or quality of being inconsistent.
2. Something inconsistent: many inconsistencies in your proposal.

...note the singularity of the word "your"...further,

Webster

1. The quality or state of being inconsistent; discordance in respect to sentiment or action; such contrariety between two things that can not exist or be true together; disagreement; incompatibility.

There is perfect inconsistency between that which is of debt and that which is of free gift.--South

2. Absurdity in argument or narration; incoherence or irreconcilability in the parts of a statement, argument, or narration; that which is inconsistent.

If a man would register all his opinions upon love, politics, religion and learning, what a bundle of inconsistencies and contrdictions would appear at last!--Swift

3. want of stbility or uniformity; unsteadiness; changeableness; variableness.

Mutability of temper, inconsistency with ourselves, is the greatest weakness of human nature--Addison

Again, make note of the definite singularity of the quotes. One person can have inconsistencies, two only if speaking as an entity...

WordNet, Princeton U.

1. The relation between propositions that cannot be true at the same time[syn: incompatability, mutual exclusiveness]
2.The quality of being inconsistent and lacking a harmonious uniformity among things or parts[ant: consistency]

Again, this applies to an individual or group of individuals speaking as a single entity...not what AR is, it is a diverse community...

"...I wasn't saying that you were inconsistent, but rather that some of the information and statements made on this board by various members are inconsistent with each other..."

And why wouldn't they be, it is a microcosm...BTW now you have qualified it by adding "with each other"...

jimHJJ(...which is what I said in the first place...)

[996turbo]

I genuinly feel sorrow for you Mr. Loser.

Anybody with the pent anger that you have shown must be in agony.
I am sincere when I say this I do not understand why you must put so much anger in to your post. Life is realy too short to go around with this anger.

Magictooth made a simple comment and you proceded to bash him for it as you do with a propensity of your post. Is it too hard for you to give a positive post. You seem to always look at the negatives in a post.

Life goes on much better when the negatives are realized but the positives are acted upon.

One should not have to worry about the proper usage or speling of a word in a silly post on a meaningless site. You however hone in on those negatives in search of something to be right on.

[Resident Loser]

"...I genuinly feel sorrow for you Mr. Loser....
Anybody with the pent anger that you have shown must be in agony.
I am sincere when I say this I do not understand why you must put so much anger in to your post. Life is realy too short to go around with this anger..."

You actually think I give a rat's rump about this $h!t...if so I feel sorry for you...it's a diversion...a pleasntry...

"...Magictooth made a simple comment and you proceded to bash him for it as you do with a propensity of your post..."

No, toothy ignored the body of my post and decided to carry on in error re: his misuse of a word...

"...Is it too hard for you to give a positive post. You seem to always look at the negatives in a post..."

Not looked much further than your nose have you? I answer a plethora of questions and direct folks to reliable sources of information on a regular basis. I also provide my opinion based on experience in sound production, sound reproduction and related fields...I always look for blatant stupidity in posts and address issues as I see fit.

"...Life goes on much better when the negatives are realized but the positives are acted upon..."

Teach me more Mahatma!

"...One should not have to worry about the proper usage or speling of a word in a silly post on a meaningless site..."

I usually take issue on said items with those who brag about their strict attention to details...oxymoronic? is that a word?

"...You however hone in on those negatives in search of something to be right on..."

I might hone a knife or chisel, but I home-in on things set before me on a silver platter...and only from the chosen ones...

jimHJJ(...good night now...)

[magictooth]

LOL - the inconsistencies that you get if you don't check the site for 5 days...

From Resident Loser:
With re: to volume, the louder unit will always seem to sound better.

PatD:
Well, I have to agree that sometimes a little softer sounds better

Who to believe?
Here is the original post. You are making mountains out of molehills when you are nitpicking a very small detail such as the one you identified. I didn't think that it was necessary in any way to further clarify or elucidate my point. I was implying that 2 posters here have diametrically opposite view points with regards to volume. It should have been clear when I cut and pasted verbatim what was posted before. I gave proper attribution to the authors, and it should have been quite clear what I was trying to get at.

Do you feel that every post here should have some legal disclaimers attached? Maybe I need you to read and acknowledge some type of end user agreement before you read my posts? In any case, I believe that enough bandwidth has been wasted on this subject. If you feel that you must have the last word on it, by all means proceed. I won't be wasting any more time on this thread.

On another more serious note, please check out my naysayers post. I would certainly appreciate any constructive feedback that you have.

[996turbo]

That is precisely what I would have expected out of you loser.

A post tearing apart what I have said and then teling me how I misused a word. I must commend you on your ability to focus in on the positives in a post.

Bravo

[mtrycraft]

Wow, an in depth and interesting answer.

You say that the level differences are what I'm keying off of. I am trying to eliminate that bias with the equipment that I have available to me. I don't see how there could be any bias at all if the volume control gets changed unsighted (by my wife) and at random between tests.

As for the sync issue, you are most likely not a musician. I am proposing a 10-15 second delay between playing each segment. With no audible cues, how can a less than 0.25 difference in synchronization play any role identifying which one is playing first. To be able to count rests for a random interval of 10-15 seconds without any audible or visual cue is impossible. Not even improbable - impossible. Consider this: if you told the symphony to start the second movement 3 full bars of silence after the end of the first movement, but that nobody could direct and nobody could do any kind of head movement, etc., you'd have 100 musicians playing at slightly different times. I seriously don't believe that my method will lend any bias.

So Mtry, are you trying to say that you DON'T believe that all players sound the same? I realize that you have often said that all well designed players sound the same, but the difference between saying "well designed" and all players is a very obscure bit of minutiae. Please for the record state what you believe about DVD players playing RBCD. Unless I'm mistaken, I believe that you constantly denigrate spending over a very modest amount of money on a DVD player (or CDP). Please specify how much money is too much money for a well designed player.

With regards to the voltage attenuation, I was thinking of something else, namely the analog knob that I have which would increase the volume by differing amounts based ont he material you play. You are correct that I was making an incorrect statment.


Now I am understanding your level difference issues. You change volumes randomly between the two. This needs to be tested as well. While I don't see anything with this, there may be something. That is not how comparisons are performed at all though.

Same for the sync issues. If you have that much delay, you will not know but your memory will suffer a lot.

If you can still identify 100% as I think you indicated, either you are getting some subconscious clue from your wife, your method is still flawed, or there is something wrong with one of the players that can only be identified by bench testing. Your protocol is not standard, so it needs to be validated.

No, not ALL players are the same. Some are designed bad in the first place, some may be too cheap.

As to cost, that is hard to tell what is too much as one can enjoy other qualities of a player besides it sonic quality. If so, then there is no answer. If only sonic quality matter, nothing else, no flexibility issue, then the $80 RCA that T$$ tested a few years ago is all you need.

[Thomas_A]

Magictooth,

have you done the test yet?

T

[magictooth]

Magictooth,

have you done the test yet?

T
Not yet. The weather's been too nice so I've been outside a lot. I will post a new post after the testing.

[Beckman]

"A good experiment design gets you the answer you need at a price that you can afford to pay. A better experiment design gets you the answer you want for less than you were willing to pay. The best experiment design gets you the best answer at the least possible cost." <http://www.strategy4doe.com/FAQ/doe.htm>

I think when experimenting with CD players a DOE or design of experiments would be more appropriate than an OFAT or one factor at a time approach. The problem with OFAT is that it is extremely difficult to use just one factor at a time, or impossible.

What I would suggest is using several experiments (DOE), and not having the listener be the one who set up the experiments. Find someone that has a good ear, not grampa who can't tell if the fire alarm is going off or the door bell is ringing. Maybe someone who has listened to a lot of different stereo equipment, but don't mention how you are conducting the experiment, just have them come in, sit down, and fill out a form that says:

better/worse/same

Test every variable seperatly.

1. First I would suggest pausing one cd player, see if the person thinks a different player is being used after each pause, don't change the volume or mention the volume difference between the two players. ONE THING AT A TIME!

2. If the person doesn't think a different player is being used between pauses add volume changes during the pauses.

3. If they still can't hear any differnce besides volume, try the described method.

Retry the experiment with several different people.

This is just an example of how one might go about doing a DOE or design of experiments to experimentaly determine something. You want to examine every variable seperatly in a systematic way. DOE is used extensively in research, particulary research that involves extremly complex systems (biology) that would be very time consuming or impossible to do using just math or physics.