what camp are you in?

[WmAx]

Your mistake here is that you still think this is all about power. It isn't. This is the typical mistake of novices who don't understand the technology, it's limits, and read only some of the papers that deal only with a part of the problem. It's a big world out there, and you can spend a lifetime investigating it.
Audio is an on going process.
d.b.

In fact, I have investigated the issue of amplifier performance in-depth, so far as the relevant parameters for human hearing are concerned.

Power factor is a very important consideration if one wants non-clipped music on dynamic passages of well-recorded/mastered music especially. But I guess that is really not the point here. The point is that I have failed to find credible published information showing a mystery factor X that some people imply exists, much as you appear to be doing in parts of this thread. Now, THD is not a mystery factor. So, please show the THD measurements for a typical audio amplifier(something like $300 Pioneer reciever, for example) into a typical reactive load that is nominally rated to match with the amplifier's rated nominal impedance load driving ability. Ensure that this amplifier is not clipping(even at maximum phase angle) at the amplitude used in the test. Now show that the THD increase that occurs at high phase angles is in fact audible according to known perceptual research on THD audibility. Of course it's not this simple to correlate, because even if the THD was a high enough level to be audible according to perceptual tests(which I highly doubt, since the ear is very tolerant of rather large amounts of THD), then you have to account for this effect is only across narrow band(s) where the high degree phase angle exists and for a momentary duration when it occurs in the particular music program. Perceptual research of THD has mainly concentrated on applying an equal level of added THD to the entire bandwidth, not narrow portions of it, so it could not be expected that the ear would be as sensitive to distortion occuring in a narrow band as compared to a broad band.

Or you could just do a properly set-up and planned DBT and show a positive difference where other known factors/measurements show that their should not be a positive difference.

I find the claims of unique amplifier properties among properly designed amplifiers to be lacking substance.

You should contact Richard Clark at a2000rich@aol.com. He has long run a $10,000 amplifier challenge. He has DBTed numerous audio professionals and audiophiles, comparing low price amplifiers to mega-dollar exotics. His test only requires that neither one is operated into clipping, that no audible noise(s) exist, and that the frequency response is comparable(he will apply E.Q. to the low-end amp to make it match the other unit if they are not comparable). The last time I checked(and many tests have already been done as of that point by Clark), no one had been able to identify a difference and win the $10,000 prize.

-Chris

 

[Dan Banquer]

What camp are you in

Should I apologize for clouding the issue with facts? Nah!
Have a nice day;
d.b.

 

[WmAx]

Should I apologize for clouding the issue with facts? Nah!
Have a nice day;
d.b.

If you have facts concerning audibility of amplifiers that are not already known, you should share them(along with the relevant citations).

-Chris

 

[Rip Van Woofer]

But they can't tell you how "it" sounds. Because "it" should be inaudible. If you want to hear about bass-string plucks and drum skins, you really want to hear about the CDs and Vinyl they're playing. $10,000 amps don't create these things out of thin air, they've always been there on the recording.

Hard to improve on such a succinct, non-technical statement of the facts! This thread could have stopped right there, IMHO.

Of course, it doesn't take a $10k amp to reveal what's on the recording. The speakers and room are what really do the job (or mess it up). That's where the money should go first...or at least after the money you spend on good recordings!

My many postings here should leave no doubt as to my "camp" choice.

 

[Dan Banquer]

What camp are you in

"If you have facts concerning audibility of amplifiers that are not already known, you should share them(along with the relevant citations), as opposed to hiding them behind claims of DBT being inadequate and other such distractions."

I have already stated enough engineering facts and principles to totally confuse you into claiming that I am not stating facts. If you understood what I was talking about you would stop a minute and think. While you're at it you keep referring to "well" designed speakers and amplifiers. Could you be a bit more specific as to what a well designed amplifier and speaker are? I'm looking for specifics here not just generalities
d.b.

 

[MDS]

Should I apologize for clouding the issue with facts? Nah!

What facts? All I see from your posts is 'Nobody understands all of the relevant issues the way I do'. But when challenged, you can't explain your facts.

I particularly like the way you twist the facts behind DBT in an attempt to refute its validity. DBT is supposed to be used to compare two devices where those two are the only variables, yet you throw in extraneous information like comparing amp a with speaker x vs amp b with speaker y. Hey why not use totally different cables and have the amps and speakers in different rooms too? Then you can say 'see, they are different'. Of course they are - you are comparing apples to oranges.

 

[WmAx]

I have already stated enough engineering facts and principles to totally confuse you into claiming that I am not stating facts.

What you have me confused about, is what exactly you are claiming makes an audible difference. You have shown zero data supporting the implication that the typical amplifier will audibly distort under typical reactive loads when not operated into clipping.

If you understood what I was talking about you would stop a minute and think. While you're at it you keep referring to "well" designed speakers and amplifiers. Could you be a bit more specific as to what a well designed amplifier and speaker are? I'm looking for specifics here not just generalities
d.b.

You refuse to address or reply to most of the questions asked in this thread and I only continue to ask questions in hopes you providing clarification/data. As for a typical amplifier; a common modern entry level recievers(Yamaha, Pioneer, HK, etc.) would suffice. These are low cost and measure rather well as a general rule. A simple sample of 3 or 4 different random units would establish what I think is a fair preliminary baseline average of typical behaviour. As for speaker load, a standard load as presented by commonly available speakers such as Infinity, Polk, etc.; most of them show very similar impedance/phase angle tolerances when measured. Of course, you can not have an exact typical anything, but you can average it and account for some reasonable percent of tolerance for the exceptional circumstance.

-Chris

 

[mtrycrafts]

You really should get out and hit the library, there is a world of relevant information that is available to you. Yes Dr. Toole has made some contributions, but your close mindedness to the so many relelvant studies and your lack of knowledge about the basics of electroincs show me you have limited your scope down to few papers. It's big world out there, but hey, maybe you need those kind of limitations to make you feel more comfortable and secure.
BTW: There is still a pretty hefty debate on harmonic distortion and audibility, and what I have learned through design over the years is "kill the upper harmonic distortion".
Audio is an ongoing process.

d.b.

Since you seem to think you have all the answers and all the studies, CITE THEM. So far, your lack of citations to support your implications is telling. YOU HAVE NONE or you would have a page by now.

 

[mtrycrafts]

Still think DBT testing is the ultimate answer?
d.b.
P.S. Neither amp is clipping during any part of the test.

It is the only GOLD STANDARD that there is. Incontestable, period, no matter how you try to distort the issues. But, you could once again try to refute it with some cited research if you have any.

 

[mtrycrafts]

And BTW: DBX in the 80's found out more about this so it's nothing new either.
d.b.

Cite them.

Tom Nousaine, ' The Great Debate: Is Anyone Winning?' Proceedings of the AES, 8th International Conference, 1990.

This reviews about 22 published DBT articles on amps, many 1000s of trials, many 1000s of listeners. Interesting results that you will not like, of course.

 

[mtrycrafts]

. I suspect this is one of the reasons that the DBT for audio power amps is not generally accepted as the absolute definitive test. .
d.b.

It is rather simple. It's not accepted because these people don't like the answers it produces so they make up any and all excuses.

 

[Rip Van Woofer]

OK boys, play nice. This is getting a little too heated. I hadn't reviewed the whole thread before putting in my 0.02.

On review, I'll refrain for now from closing the thread as was suggested in a PM. This debate can go on forever. It can also be debated with civility.

I'll also consider moving it to The Steam Vent.

 

[MacManNM]

What facts? All I see from your posts is 'Nobody understands all of the relevant issues the way I do'. But when challenged, you can't explain your facts.

I particularly like the way you twist the facts behind DBT in an attempt to refute its validity. DBT is supposed to be used to compare two devices where those two are the only variables, yet you throw in extraneous information like comparing amp a with speaker x vs amp b with speaker y. Hey why not use totally different cables and have the amps and speakers in different rooms too? Then you can say 'see, they are different'. Of course they are - you are comparing apples to oranges.

I dont think Dan ever said the DBT wasnt valid. He is stating that it is a tool in choosing an amp. Different situations produce different results.

 

[MacManNM]

In fact, I have investigated the issue of amplifier performance in-depth, so far as the relevant parameters for human hearing are concerned.

Power factor is a very important consideration if one wants non-clipped music on dynamic passages of well-recorded/mastered music especially. But I guess that is really not the point here. The point is that I have failed to find credible published information showing a mystery factor X that some people imply exists, much as you appear to be doing in parts of this thread. Now, THD is not a mystery factor. So, please show the THD measurements for a typical audio amplifier(something like $300 Pioneer reciever, for example) into a typical reactive load that is nominally rated to match with the amplifier's rated nominal impedance load driving ability. Ensure that this amplifier is not clipping(even at maximum phase angle) at the amplitude used in the test. Now show that the THD increase that occurs at high phase angles is in fact audible according to known perceptual research on THD audibility. Of course it's not this simple to correlate, because even if the THD was a high enough level to be audible according to perceptual tests(which I highly doubt, since the ear is very tolerant of rather large amounts of THD), then you have to account for this effect is only across narrow band(s) where the high degree phase angle exists and for a momentary duration when it occurs in the particular music program. Perceptual research of THD has mainly concentrated on applying an equal level of added THD to the entire bandwidth, not narrow portions of it, so it could not be expected that the ear would be as sensitive to distortion occuring in a narrow band as compared to a broad band.

Or you could just do a properly set-up and planned DBT and show a positive difference where other known factors/measurements show that their should not be a positive difference.

I find the claims of unique amplifier properties among properly designed amplifiers to be lacking substance.

You should contact Richard Clark at a2000rich@aol.com. He has long run a $10,000 amplifier challenge. He has DBTed numerous audio professionals and audiophiles, comparing low price amplifiers to mega-dollar exotics. His test only requires that neither one is operated into clipping, that no audible noise(s) exist, and that the frequency response is comparable(he will apply E.Q. to the low-end amp to make it match the other unit if they are not comparable). The last time I checked(and many tests have already been done as of that point by Clark), no one had been able to identify a difference and win the $10,000 prize.

-Chris

Hmmmmmm, lets see, EQ an amp so that it matches the one it's being compared to, run it well within it's limits and see if you can tell the difference. I can see why no one has won the 10k. That is a joke. The FR of an amp is one of the inherent characteristics of the unit, if you have to EQ one, how is that a fair test?

 

[WmAx]

Hmmmmmm, lets see, EQ an amp so that it matches the one it's being compared to, run it well within it's limits and see if you can tell the difference. I can see why no one has won the 10k. That is a joke. The FR of an amp is one of the inherent characteristics of the unit, if you have to EQ one, how is that a fair test?

It would not be fair if one wanted to see if the amplifiers sounded different due to the sum of differences(which can include purposely modified frequency response, etc.). The point of this type of test is to see if any factors that are not known by existing perceptual research influence the sound of an ampllifier. Clark's reason for the testing he does is in response to claims of mysterious parameters that supposedly affect amplifier sound.

-Chris

 

[MacManNM]

It would not be fair if one wanted to see if the amplifiers sounded different due to the sum of differences(which can include purposely modified frequency response, etc.). The point of this type of test is to see if any factors that are not known by existing perceptual research influence the sound of an ampllifier. Clark's reason for the testing he does is in response to claims of mysterious parameters that supposedly affect amplifier sound.

-Chris

If they sound different, then they sound different. Period. That is the whole point, to see if they sound the same, if the mfgr changed the FR by design then I would think that that is something worth noting. If you are buying an amp and it sounds better to a person, then that may well be the reason.

 

[rollinrocker]

Do we actually think we are going to change the beliefs of those in opposing camps? Both sides are adamant and passionate in their statements. We don't really expect the other to suddenly see our point of view do we? "By golly, you've got a point there, there IS merit to your argument!" NOT GONNA HAPPEN!

 

[mtrycrafts]

Do we actually think we are going to change the beliefs of those in opposing camps? Both sides are adamant and passionate in their statements. We don't really expect the other to suddenly see our point of view do we? "By golly, you've got a point there, there IS merit to your argument!" NOT GONNA HAPPEN!

Credible evidence rules and changes peoples minds on some sides, those who are after facts, not fiction

 

[PENG]

Do we actually think we are going to change the beliefs of those in opposing camps? Both sides are adamant and passionate in their statements. We don't really expect the other to suddenly see our point of view do we? "By golly, you've got a point there, there IS merit to your argument!" NOT GONNA HAPPEN!

You're right, this debate will never end. You started it, didn't you?

 

[mtrycrafts]

If they sound different, then they sound different. Period. That is the whole point, to see if they sound the same, if the mfgr changed the FR by design then I would think that that is something worth noting. If you are buying an amp and it sounds better to a person, then that may well be the reason.

Not all amp DBTs used EQ, yet the results are the same. Most amps are flat withing .25dB where it matters the most 100Hz to 16kHz. Below and above, the hearing is much less sensitive and need a whole bunch of level mismatch which is still not in modern amps.
But, you can always level match to .1dB at 1kHz and go for it. See if you can differentiate 15 of 20 guesses. The probability does not favor you.

This didn't and 3 people could not do it, but then, they were not certified 'golden ears.'

http://groups.google.com/group/rec.audio.opinion/browse_frm/thread/664b8681ab141263/3fd91bcb6a1522a0?hl=en&lr=&ie=UTF-8&oe=UTF-8&rnum=1&prev=/groups?q=sunshine+stereo+yamaha+abx+nousaine&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=501fl6%24ac3%40oxy.rust.net&rnum=1#3fd91bcb6a1522a0