Amp DBT's - disagree with conclusions

[Tom Bombadil]

Some have said that DBTs between relatively inexpensive ($250) amps and relatively expensive (>$3000) amps have proven that there are no audible diferences. Might I ask whether the people who participated in those tests were:
a) having good auditory capacity
b) aware of sounds enough to tell the difference

Enough people have listenened to magnaplanars and said that if I was all that interested in music reproduction - should really get the bose acoustimass type speakers. !!
If such people were participating in DBTs - well - all would come to naught. The Audio industry suffers (IMNHSO) because people (at large) are not all that attuned to sounds. Many are well attuned to visual/TV. They (IMNHSO) may pay some attention to sharp transients but they are satisfied with a wide range of quality of transients (ringing of swords, arrows hitting targets etc). Who even knows what a real sword fight should sound like ? Who uses bows and arrows enough to know what they sound like ?

I recently heard ROTEL 1080, Musical Fidelity HT100, Myryad MA240 swapped in my system - not by DBT...they are all comparably priced amps (all in the $1000 range) and the differences were not small. Music was mostly Jazz - Chesky Discs.

So although a "proper" DBT may be the answer finally - question is - has a "proper" DBT ever been done on Amps ? What kind of participants/music/sounds would be chosen ? Dont get me wrong - I am not really against DBTs but if the perfect DBT is not done yet - why accept it's/their imperfect conclusions ?

[Pat D]

No one maintains that all amps sound the same, let alone sound the same under all conditions. However, many amplifiers do seem to sound the same if operated within their design limits if they have a flat frequency response, low noise, low distortion, high input impedance and low output impedance. Severe clipping is audible, for example. Magnepans typically provide a difficult load for an amplifier. Some amps have a high output impedance (most tube amps, but some SS ones) and this will affect the frequency response into most speaker loads.

You seemed to have compared the amps in a casual audition, sighted, so you knew which ones you were auditioning. Human beings tend to overdetect differences in sighted auditions. I doubt that you level matched them very closely; even channel balance differences can make a difference.

Improperly set up DBTs usually end up with false positives.

[E-Stat]

So although a "proper" DBT may be the answer finally - question is - has a "proper" DBT ever been done on Amps ?

You will find an amusing circular argument when it comes to answering your question. Plenty of tests have been done on mid-fi gear with predictable results. Aside from the lone story of the dealer in Florida who couldn't tell the difference between a Yamaha receiver and a Levinsion amp, none of the advocates here have been able to find any using high end gear. So, the conclusion is that because little or no differences have been detected using mid-fi gear, then there is no point to test high-end gear. Right.

I have also pointed out that there are a grand total of ZERO manufacturers of ANY audio product who, if they have conducted DBT tests, find them worthy enough to make a single mention of the tests or results in their advertising, product literature, or manuals. That sure is a glowing endorsement of their value, isn't it?

rw

[Woochifer]

I have also pointed out that there are a grand total of ZERO manufacturers of ANY audio product who, if they have conducted DBT tests, find them worthy enough to make a single mention of the tests or results in their advertising, product literature, or manuals. That sure is a glowing endorsement of their value, isn't it?

rw

Another circular argument though is that if the DBT tests show no significant differences, then what benefit would it be to the manufacturers to highlight tests that do not demonstrate that their products are preferable to others?

If DBTs not showing up in advertising or product literature is a "glowing endorsement of their value" then does that mean that all of the product features and claims that DO make their way into an ad or brochure are therefore more valuable than DBT testing? Ads and product brochures are places to make claims, not to show the proof.

[E-Stat]

...then does that mean that all of the product features and claims that DO make their way into an ad or brochure are therefore more valuable than DBT testing?

I merely observe the obvious. Perhaps each and every audio company on the planet can explain why it is they find no value in trumpeting their scientific tests, if in fact they conduct them.

Ads and product brochures are places to make claims, not to show the proof.

Showing the proof and mentioning the source of their proof are two different animals. If I had some incredible scientifically backed proof of some claim, I'd sure make the slightest mention of it.

rw

[Tom Bombadil]

Just to point out some contrast...I make incredilbly important decisions e.g. changing lanes in fast traffic without rigorous tests...individual judgement must count for something...

and I am saying in the absence of the "perfect test" which has hitherto never happenned.

Re:"Improperly set up DBTs usually end up with false positives." - okay then...why not just move on with our lives...

I will certainly consider any DBTs that will be performed but will use that as input to my biased listening and check whether I hear what they say or not...because it seems that I am stuck with my biased hearing and there's no getting around that.

I will dig around for the post I read that said something to the effect - and I paraphrase here - "All reasonable Amps sound the same".

Here's more detail on my biased listening:
What really hit me was that I really **liked** the looks of the ROTEL-1080, the myryad amp is this dull grey blob looks pretty hideous - does not weigh much - and is generally un-impressive by any description, the Musical Fidelity HT100 is better looking and weighs a TON - very impressive - have had it for over 2 years and have been very happy with it. I had heard a smaller cousin of the Rotel playing and had liked it at the shop - so I was quite convinced it would be good.

All said and done the Rotel sucked big time - there were huge differences between what it played at lower volumes and what it did at medium/loud volume levels. The difference was much more obvious than the decision of **changing lanes on highway**. So sadly i had to reaturn the very good looking Rotel.

The Myryad and HT100 were both "Good" but again very different sounding. I am quite frankly not a believer that all amps sound the same - after this performance of similarly priced amps - which are all not cheap and would hope that they all qualify as "resonable design" and were played well-within their design parameters. I dont play loud.

- Tom

No one maintains that all amps sound the same, let alone sound the same under all conditions. However, many amplifiers do seem to sound the same if operated within their design limits if they have a flat frequency response, low noise, low distortion, high input impedance and low output impedance. Severe clipping is audible, for example. Magnepans typically provide a difficult load for an amplifier. Some amps have a high output impedance (most tube amps, but some SS ones) and this will affect the frequency response into most speaker loads.

You seemed to have compared the amps in a casual audition, sighted, so you knew which ones you were auditioning. Human beings tend to overdetect differences in sighted auditions. I doubt that you level matched them very closely; even channel balance differences can make a difference.

Improperly set up DBTs usually end up with false positives.

[Woochifer]

I merely observe the obvious. Perhaps each and every audio company on the planet can explain why it is they find no value in trumpeting their scientific tests, if in fact they conduct them.

But, if the tests are inconclusive and trumpet no audible differences, then what is there to claim? Speakers companies are always mentioning how they use DBT in how they voice their speakers. Then again, speakers have significant differences that are measureable and can be correlated to positive results. Differences between amps fall under a much narrower threshold.

Showing the proof and mentioning the source of their proof are two different animals. If I had some incredible scientifically backed proof of some claim, I'd sure make the slightest mention of it.

rw

But, again you're presuming that such positive trials exist. If the DBTs proved inconclusive, then what ad exec in their right mind would tout in an ad that their megabucked amp sounds no different than something that costs 10x less? The ad will tout how much build and capacity and features go into the amps, but if no DBT can verify that these additions make a conclusive difference to the sound quality, then no quotable material to insert into the ads, brochures, and owner's manuals is available. And so these debates spin on and on ...

[E-Stat]

But, if the tests are inconclusive and trumpet no audible differences, then what is there to claim?

If there truly are no audible differences, then the low end companies could claim that their $250 receiver sounds exactly like $30,000 monoblocks. I say if.

Speakers companies are always mentioning how they use DBT in how they voice their speakers.

Who might those be who are "always mentioning how they use DBT"?

If the DBTs proved inconclusive, then what ad exec in their right mind would tout in an ad that their megabucked amp sounds no different than something that costs 10x less?

As I mentioned above, turn that example around and explore the obvious benefits.

rw

[Woochifer]

If there truly are no audible differences, then the low end companies could claim that their $250 receiver sounds exactly like $30,000 monoblocks. I say if.

And that would be a complete misinterpretation of what the DBT "proves." A nonconclusive result is just that. Proves nothing, and supports no claims of any kind. A difference might exist, or it might not. Whether you believe such difference exists or not, the DBT in this case would not constitute the "proof" that you hang your beliefs on.

And the thing about low end companies is that even they will produce a full lineup of receivers and/or amps. If they start talking about how a nonconclusive DBT result "proves" that there are no audible differences between an entry level model and the megabuck amps, then it would ALSO tell the customer that such nonaudibility also applies between a company's entry level models and their top-of-the-line models. I doubt that even an entry level company would pursue that as a marketing strategy, since they could no longer try and sell their higher priced models on perceived sound quality improvements. Besides, it's a lot easier to try and persuade customers by quoting gaudy wattage specs.

Who might those be who are "always mentioning how they use DBT"?

For starters, Harman, Paradigm, PSB, and Energy, whether in their white papers, product brochures, or magazine interviews, at some point have all made mention of the testing that they do during the development process -- testing that includes DBT listenings to help determine the type of voicing that they should use in their products.

[Feanor]

...So although a "proper" DBT may be the answer finally - question is - has a "proper" DBT ever been done on Amps ? What kind of participants/music/sounds would be chosen ? Dont get me wrong - I am not really against DBTs but if the perfect DBT is not done yet - why accept it's/their imperfect conclusions ?

I think the answer is "yes": I bought my Phase Linear 400 amp many years ago after reading an article in a magazine that compared about a dozen high-power amps using DBT-type methods. Was that magazine called "Sound Advice" -- I can't remember but I still have a copy and will check. The method were explained in detail and, though I don't recall the details, is seem rigorous to me, a non-scientist.

Apparently the listening panel had no problem hearing differences among these medium and high-price amps. Of course, the PL 400 came out on top -- many people then and now would say that that in itself proved DBT doesn't work, (LOL)!

It wasn't scientific, but I'm totally sure I heard "huge" improvement going from my former, entry-level NAD C270 to my current, low-high-end Bel Canto eVo2i.

BTW, I guess your another JRRT fan?

[E-Stat]

For starters, Harman, Paradigm, PSB, and Energy, whether in their white papers, product brochures, or magazine interviews, at some point have all made mention of the testing that they do during the development process -- testing that includes DBT listenings to help determine the type of voicing that they should use in their products.

Apparently, it's a Canadian thing. Of the three you mentioned, only Paradigm makes mention of DBTs on their website for consumers to see. Regarding Harman, you may be referring to another NRC guy, Toole. The search engine on the Harman International website is mute to mention of "DBT" or "double blind test".

rw

[Pat D]

Apparently, it's a Canadian thing. Of the three you mentioned, only Paradigm makes mention of DBTs on their website for consumers to see. Regarding Harman, you may be referring to another NRC guy, Toole. The search engine on the Harman International website is mute to mention of "DBT" or "double blind test".

rw

PSB mentions DBTs as well on their site:

http://www.psbspeakers.com/NRC.html

Apparently, PSB still makes extensive use of the National Research Council facilities.

[E-Stat]

PSB mentions DBTs as well on their site: Apparently, PSB still makes extensive use of the National Research Council facilities.

I sit corrected. Two out of hundreds. OK.

rw

[Woochifer]

Apparently, it's a Canadian thing. Of the three you mentioned, only Paradigm makes mention of DBTs on their website for consumers to see. Regarding Harman, you may be referring to another NRC guy, Toole. The search engine on the Harman International website is mute to mention of "DBT" or "double blind test".

http://www.harman.com/wp/index.jsp?articleId=1018
http://www.harman.com/wp/index.jsp?articleId=64

And given that blind tests (preferably double blind) were written as part of the recommended subjective loudspeaker evaluation standard for the AES, I would guess that the companies I listed aren't alone in using blind tests as part of their internal evaluations. This paper states that these standards are put in place in order to reduce testing errors. Problems with sighted listenings are but one part of the potential errors to consider.

http://www.aes.org/standards/b_pub/aes20-1996.pdf

[Woochifer]

I sit corrected. Two out of hundreds. OK.

... that you are aware of. Unless you are privvy to what all audio companies do as part of their design and research process, your inneuendo about the DBT methodology doesn't say anything.

Are you implying that aside from the "Canadian thing", everybody else does their listening tests under sighted conditions? Or that everything everybody else designs is based on measurements alone with no listening involved?

[E-Stat]

... that you are aware of. Unless you are privvy to what all audio companies do as part of their design and research process, your inneuendo about the DBT methodology doesn't say anything.

I will repeat my original comments. Precious few audio companies of any sort make even the least mention of using DBTs in their products. I believe that absense makes a statement.

... Are you implying that aside from the "Canadian thing", everybody else does their listening tests under sighted conditions?

Yes. Talk to Wendell Diller. Talk to Carl Marchisotto. Talk to Roger West. Talk to any number of designers. DBTs are great only for detecting gross differences.

Or that everything everybody else designs is based on measurements alone with no listening involved?

Certainly not. Measurements alone are woefully inadequate to convey all aspects of musical reproduction.

rw

[Woochifer]

I will repeat my original comments. Precious few audio companies of any sort make even the least mention of using DBTs in their products. I believe that absense makes a statement.

Absence does not make any statement, other than leaving the window open for speculation and inneuendo.

Just because they do not explicitly make mention of it in their marketing materials does not mean that they exclude blind tests from their development process altogether. You're presuming that a company outlines everything in their promotional materials about their product testing and research. Just because a company does not mention listening tests in their advertising, does not mean that they aren't a part of the development process. I mean, several restaurant chains and food manufacturers that I know of do blind taste comparisons of their products and menu items all the time to determine what customers prefer. So, if their advertising doesn't feature how they do their product testing, then it means that it doesn't exist and blind testing is therefore worthless? Interesting logic.

Yes. Talk to Wendell Diller. Talk to Carl Marchisotto. Talk to Roger West. Talk to any number of designers. DBTs are great only for detecting gross differences.

Three designers that you've talked to does not equate to "any number of designers." And what is your criteria for defining "gross differences"? Is that the same as MEASUREABLE differences? That's exactly what the DBTs used by those aforementioned companies are attempting to correlate -- how measureable differences correspond to subjective impressions and preferences.

Certainly not. Measurements alone are woefully inadequate to convey all aspects of musical reproduction.

And biased sighted listenings are inadequate for making consistent and reliable observations between different components.

[Mr Peabody]

As many audio issues such as; tube vs. solid state, digital vs. analog and DBT or not to DBT, there are 2 hardline camps. The late Julian Hirsch of Stereo Review fame held to the belief that good amps sound the same and attributed any differences heard to environment (room set up) or variations of components. I personally didn't buy that then and still do not. I have personally done listening where I switched one amp out of a system and put another in with no other changes and have heard big differences. I don't buy in to that psycho stuff where we influence ourselves to believe something sounds better. Who wants to buy a $2k amp when a $200. one sounds the same. I also believe that when people do DBT's that they feel pressure, hence the word TEST. I don't think DBT's are a relaxed thing. Not many people perform well under pressure. Tom also makes a good point about who is taking these DBT's I have ridden with people in their car where the balance was off or the tone controls messed up and they were oblivious to the fact. Something like that gets on my nerves and I have to ask to adjust it. My friend who has a nice Arcam integrated amp, cdp and Dynaudio speakers listens to the system with the bass maxed out most of the time. I hate it, yet cannot convince him it's not meant to do that. I have walked into peoples house and known their HT system was hooked up wrong as soon as it was turned on. They couldn't tell. My cousin was using analog from his DVD to receiver, which prevents 5.1, and had all 5 speakers playing at once somehow and thought he had surround sound. I took him out and bought a digital cable and hooked everything up properly, hell he liked it better the other way. He says, "da...... most of the sound is a commin from the one speaker". Another guy I know kept bragging about his HT system and how good the bass and sound was, I finally went to check it out, he had ALL the speakers on the entertainment center where the TV was and the sub on one of the shelves. I tried to explain how surround sound was to work and he should move is sub out into a corner, OR at least on the floor. He looked at me like I was from Mars. It's true some people just don't get it. And a very small percentage have ever listened to true high end gear long enough to form an opinion or educate their ear. I've been there. I told the story before about how I went into a high end shop for the first time with my Great White cd and had them through it into a Krell system driving some big $25k Dynaudio speakers and thought my system sounded better because it had more midbass. Well the truth was my cd was not that well recorded and I heard it more accurate for the first time. He through in the Paula Cole cd and that system sounded like it would bring the building down. I find that most people with an untrained ear tend to equate good sound to loudness. In DBT's the sound level is evenly matched, so hence, your results, all amps sound the same. I have a real hard time believing that someone familiar with sound equipment couldn't hear a tonal difference between some amps. There are some amps who have a similar sonic presentation that would make things more difficult. For instance, it would be more difficult to hear a difference between Krell, Bryston or Levinson than it would if you compared one of them to a McIntosh or maybe a Musical Fidelity.

[kexodusc]

I have a real hard time believing that someone familiar with sound equipment couldn't hear a tonal difference between some amps.

There have been numerous cash rewards for being able to "pass" double blind tests for differences in amplifier sounds...can't remember the exact name, but some guy's got an open invitation with $10 thousand on the line or so if anyone can get do this...so far, no one's been successful...only Audiophiles even hear of this type of thing. Ask around, search the threads here, someone will direct you to it I"m sure.

I'm not dumb enough to say that amps don't sound different, but I know ALL of us here are guilty of making very miniscule differences seem like fantastic cosmic anomalies.

The question shouldn't be "does it sound different"...it should be "does it sound different enough to justify the cost"....

Just my $0.02 worth...

[Woochifer]

I'm not dumb enough to say that amps don't sound different, but I know ALL of us here are guilty of making very miniscule differences seem like fantastic cosmic anomalies.

The question shouldn't be "does it sound different"...it should be "does it sound different enough to justify the cost"....

Just my $0.02 worth...

Thank you kex for distilling it down to the essentials. I'm not a diehard objectivist by any stretch (my many past scrums with mtry and other measurebutdon'tlisten types attest to that), but at the same time I also think it's the height of naivety to presume that biased sighted listenings are more valid and reliable than any and all measurements.

That goes back to your point about how subtle differences somehow turn into "night and day" improvements. If these differences are so huge, then shouldn't they be obvious under blind conditions? Actually participating in blind listening sessions can be a very eye opening experience. When I did them, the differences that I thought I could perceive under sighted conditions were more subtle or even nonexistent under blind conditions.

I've been around the hobby long enough to have heard differences between amps, but are they big differences? Hardly (tubes are a different story), and the degree depends on the speakers connected to them and the load conditions. Are there audible differences between home theater separates and receivers? IMO, yes there are. Are they significant enough to justify a 4x price difference? Not the way that my budget is currently setup.

BTW, you're making WAY too much sense to be the "Next Woochifer"! When you get around to starting threads on woofer porn, then okay you might be on your way ... for better or for worse!

[kexodusc]

BTW, you're making WAY too much sense to be the "Next Woochifer"! When you get around to starting threads on woofer porn, then okay you might be on your way ... for better or for worse!

Pfff, just wait till you see my 3 part posting on room treatments, subwoofer setup, and parametric equalization.

By the way, Wooch's woofer porn post gave me an idea for an awesome HT tweak...For all of us with 12" and 15" woofers that find them just a bit too slow, or with smaller woofers that find them too tight - run down to your local drug store and pick up some KY-Jelly...have your partner apply it to your woofer and F-E-E-L the smooth, velvety bass....

[musicoverall]

[QUOTE=kexodusc].

The question shouldn't be "does it sound different"...it should be "does it sound different enough to justify the cost"....QUOTE]

Agreed. Then the question becomes "how much of an improvement is worth how much to you" - a most personal matter. Many people would be thousands of dollars for a, say, 2% improvement. I would if I had that kind of scratch to throw around on audio gear (i.e if there wasn't so much GREAT music out there waiting for my greedy fingers to stumble across it) and many people wouldn't.

I wouldn't describe amp differences, particularly SS amps, as "night and day". However, if I could choose, there is usually one of two SS amps I'm auditioning that I would prefer to have.

[kexodusc]

I get more ticked off at the subjectivists trying to tell people that there are huge night and day differences and that if you can't hear it, you must be a tone-deaf idiot, and the objectivists that refuse to respect people's opinions of what they hear.

Most flame-wars start out by someone insulting another person's gear, or choice to purchase something for whatever reason...these snobby elitist types have insecurity issues, I think.
Funny, you can insult an audiophile's mother and walk away, but insult their Lexicon, Denon, Krell or McIntosh or whatever and you have a blood feud on your hands.

Besides, everyone knows my gear is better than theirs. :P

[Woochifer]

Pfff, just wait till you see my 3 part posting on room treatments, subwoofer setup, and parametric equalization.

By the way, Wooch's woofer porn post gave me an idea for an awesome HT tweak...For all of us with 12" and 15" woofers that find them just a bit too slow, or with smaller woofers that find them too tight - run down to your local drug store and pick up some KY-Jelly...have your partner apply it to your woofer and F-E-E-L the smooth, velvety bass....

My young padawan, yours is the path to the dark side! Only with a fully extended and even sounding bass as your ally can you conquer the room induced effects. Taking the fast and easy way can only make you an agent of evil!

A 3 part posting?! But, incomplete is your training! Remember the lessons inside the cave .. errr ... Best Buy ... oh ... uh ... Circuit City ... uh...

[musicoverall]

I get more ticked off at the subjectivists trying to tell people that there are huge night and day differences and that if you can't hear it, you must be a tone-deaf idiot, and the objectivists that refuse to respect people's opinions of what they hear.

Yes... and the objectivists that refuse to listen and the subjectivists that refuse to even consider that measurements tell us "something" about what is audible. I believe that when there are two widely divergent sides to an issue, the truth usually lies somewhere in the middle.