Testing audiophile claims and myths - Page 7

Quote:

Originally Posted by Ham Sandwich 

That was very likely Bose.  I sat through one of their demos and that's exactly what they did.  But more than a demonstration of how sight can be misleading, it was more of a demonstration of how music you are unfamiliar with can be misleading.  Especially if those doing the demo intentionally make it misleading.  The music used for the demo wasn't really music, it was more like movie sound effects and movie soundtrack muzak.  Nothing that you could be familiar with and be able to translate how it should sound on a real stereo.  Sounds that could be EQed and carefully chosen to not demonstrate the hole or discontinuity the Bose system almost certainly has between the sub and the mains.  An interesting demo of how audio tricks can deceive you.

Yea its Bose. But even before they moved the covers I noticed cracks in the sounds which I thought it was werid. Then they removed the covers and I'm like that is why the sound cracks. Too loud/much power into drivers too small can often do that from my limited experience with speakers.

But I was impressed when they covered it with a box and it still sounded the safe due to their dynamic changing whatever. Maybe I dunno speakers enough but that was quite interesting in my opinion.

Undoubtedly, the frequency response is the dominant determinant of the subjective quality. However, the study's target precision was at the level of 85%. There are other factors influencing the subjective quality that can fill the remaining 15%.

For example, intermodular distortion, which can be quite high in full-size dynamic headphones, typically employing a flexible diaphragm that exhibits increased distortion in high frequency bands in the presence of strong bass. This is much less of an issue in rigid-cone loudspeakers. Apparently, AKG K7xx series fight the intermodular distortion with uneven-thickness, more rigid on average diaphragm, and I believe it helps. 

Regarding the "audiophile myths", I think they are so hard to resolve because of the individual variation of sensitivity to distortions. I, for example, can easily distinguish a flat-frequency-response amplifier with 0.1% THD from one with 0.01% THD. Apparently, many other people can't.

On the other hand, I don't have ability to tell the exact note which most closely corresponds to an arbitrary pure sine wave, while many musicians can do it with ease. Correspondingly, I can still listen with pleasure to a music slightly moved up or down the music scale (detuned), while I perceive any amplifier with over 0.03% THD as "harsh" or "dirty".

So, I fully believe that some people can hear differences brought about by different cables, if the capacitance/inductance/resistance of these cables differs sufficiently to cause audible changes in the frequency-specific amplitude and/or phase response of certain amplifiers, passive crossovers, and dynamic speakers.

Once long ago I owned an amplifier with improper shielding. The amp would drastically change its characteristics based on capacitance-to-ground of its surroundings - an unintended proximity sensor if you will. Not only a different cable, but sitting far away or close to the amp would change the sound - I kid you not!

I also know that for my specific active speakers setup I would need to extend the balanced and well-shielded cables to about half a mile to start hearing audible difference, so this is a no-issue for me now. Nether can I hear any difference between 4 feet and 12 feet headphone cables of the "good yet cheap" variety I'm using, so that's not an issue either. But that may well be because I only use properly constructed amps with beefy power supplies and decent high-end headphones. Other people's mileage may vary.

Quote:

Originally Posted by timar 

I'd like to add another empirical study (this time conducted on a scientifical level), which should be of greatest interest here, since it especially deals with headphones.

 

Part one is theory, part two is the empirical study:

http://www.cpt.univ-mrs.fr/~briolle/11thAESpart1.pdf

http://www.cpt.univ-mrs.fr/~briolle/11thAESpart2.pdf

 

The study was conducted for the international Audio Engineering Society and shows, in short, that if the frequency response of different headphones is accurately measured, one pair of headphones can be equalized to give the same subjective impression/quality like any other pair, just by simulating its frequency response.

 

Conclusion is, that the sound of headphones of some basic quality (e.g. THD well below 1%) is determined (almost) exclusively by their frequency response. All those fancy audiophile terms like soundstage, resolution, clarity et al are nothing but functions of the actual frequency response.

Quote:

Originally Posted by Krav 

Regarding the "audiophile myths", I think they are so hard to resolve because of the individual variation of sensitivity to distortions. I, for example, can easily distinguish a flat-frequency-response amplifier with 0.1% THD from one with 0.01% THD. Apparently, many other people can't.

 

while I perceive any amplifier with over 0.03% THD as "harsh" or "dirty".

 

 

Once long ago I owned an amplifier with improper shielding. The amp would drastically change its characteristics based on capacitance-to-ground of its surroundings - an unintended proximity sensor if you will. Not only a different cable, but sitting far away or close to the amp would change the sound - I kid you not!

 

 

 

Are you able to verify these findings with level matched blind tests ?

The point of this thread is to examine decent evidence for and against such frequently made claims. Claiming the ability to detect differences when you know in advance that something is changed and you know the nature of the change is not very strong evidence. It does not mean you cannot detect these differences, but it does not constitute proof either.

As for cables, I have tested cables blind and with measurements , the differences are generally so small as to be inaudible, only when the design is pathological is it likely to make a difference, for instance even though the unshielded cables I tested have very high (relatively ) noise it was not practically audible. I have posted samples from my experiments elsewhere, to date nobody has been able to DBT the samples.

For the THD, I think the answer would be yes. 0.1% and 0.01% sound very differently to me personally, with the same decent transducers and quality source material of course. I never participated in a blind test between the two, yet on a number of occasions I listened to supposedly high-end solid-sate amplifiers, which I knew nothing about, didn't like them, only to find out later that they were over 0.03% THD. And wise versa, every once in a while I come across one that I don't know anything about, like it intensely, and find out later its THD is well below 0.03%.

Yet another data point is that once I owned an amp which I initially liked but gradually, over the course of 5 years, stopped liking and sold. Found out much later that this particular model was afflicted by serious "drying electrolytic capacitors" issue that would gradually shift at least one of its amplification stages from A/B regime to the B and beyond, resulting in increase of THD at low volumes.

I think I do understand the concept of blind testing, the amazing strength of placebo effect, and what statistical significance means. On the other hand, I also know how large the genetic variations between humans are and how intricate the proper design of an experiment is.

For instance, all blind audio equipment tests I heard about about so far used curtains to hide the equipment. The curtain may attenuate higher frequencies and thus bring down to below audible threshold the higher-order distortion harmonics that would be there in an un-covered speaker response.

In my home system, only subwoofer's speaker is behind cloth. The rest of transducers, all 16 of them, are directly coupled to air, and this makes huge difference in what I perceive as clarity of sound. Walk into a store that sells professional monitors and try to find a single high-end speaker with non-directly-coupled mid and hight frequency transducers. There is a good reason for that preference by people who judge the quality of mixes professionally all day long every working day.

Another factor not very well controlled in some of the blind studies I read about is the quality of source material. Most pop music CDs sound very similar to me on a mid-level-quality stereo system in my daughter's bedroom and the highly accurate system in our living room. Yet the difference between these systems when a decent SACD or Blu-Ray plays is nothing short of stunning.

Lots of recordings the general population listens to are already pre-distorted, so it is very difficult to discern the more subtle distortions introduced by the amplification tract or transducers against the backdrop of massive deliberate distortions aimed at increasing subjective loudness/punchiness/liveliness/whatever of the music on a lesser-quality equipment.

On the other hand, when I listen to a piece of classical music or, say, a Pink Floyd album, created by extremely gifted musicians and engineers with lots of experience using the best equipment in the world, I want to hear exactly what they wanted me to hear, without phantom sounds, veiling, fuzziness, and dirtiness due to the sound reproduction tract distortions.

I'm with you on the cables myth. I think 99.99% of it is due to the placebo effect, occasionally reinforced by people with really bizzarre setups that could be indeed tripped by a particularly bad cable. With proper systems, just buy a moderately thick copper cable with clean connectors, and you'll be just fine.    

Quote:

Originally Posted by nick_charles 

 

Are you able to verify these findings with level matched blind tests ?

 

The point of this thread is to examine decent evidence for and against such frequently made claims. Claiming the ability to detect differences when you know in advance that something is changed and you know the nature of the change is not very strong evidence. It does not mean you cannot detect these differences, but it does not constitute proof either.

 

As for cables, I have tested cables blind and with measurements , the differences are generally so small as to be inaudible, only when the design is pathological is it likely to make a difference, for instance even though the unshielded cables I tested have very high (relatively ) noise it was not practically audible. I have posted samples from my experiments elsewhere, to date nobody has been able to DBT the samples.

Note that I am not making any assumption about your ability to distinguish between 0.1% and 0.01% THD in an amp.

But the way your data point was gathered would not make the placebo effect irrelevant. You friends or the seller who introduced you to those amps may not have told you the THD measures but they could have said something about "the incredible accuracy of the amp"or the look of the amp may have influenced your judgment. I have found that the product's look often match how it was designed, well engineered products with excellent measurements tend to look somewhat professional, or have a luxury/high tech feeling. New products that look vintage tend to have been designed more by ear than by computer simulation. The philosophy of the design match the customer's expectations. Simply by looking at a amp, I can often tell if it will measure well (considering the product category). That's why I would say one is not immune to placebo in non blind conditions, you would expect a level of THD based upon looks alone.

Secondly, logically speaking, THD is not that important in an amp, less THD means better design of course, but speakers (or headphones) usually have a THD an order of magnitude superior to amps, thereby drowning the THD of the amp. That's not saying an amp with a bad THD will sound good, but the bad THD may be the one fault that have no sonic impact among many others.

Your second "data point" with your personal amp tells us nothing, just that one of the reason it sounds bad MAY have been worsening THD.

What I wrote is about the unscientific approach of data gathering, your data should be considered feelings and opinions, not proofs.

Quote:

Originally Posted by Krav 

For the THD, I think the answer would be yes. 0.1% and 0.01% sound very differently to me personally, with the same decent transducers and quality source material of course. I never participated in a blind test between the two, yet on a number of occasions I listened to supposedly high-end solid-sate amplifiers, which I knew nothing about, didn't like them, only to find out later that they were over 0.03% THD. And wise versa, every once in a while I come across one that I don't know anything about, like it intensely, and find out later its THD is well below 0.03%.

 

Yet another data point is that once I owned an amp which I initially liked but gradually, over the course of 5 years, stopped liking and sold. Found out much later that this particular model was afflicted by serious "drying electrolytic capacitors" issue that would gradually shift at least one of its amplification stages from A/B regime to the B and beyond, resulting in increase of THD at low volumes.

I think this is a misconception, sorry. While it is true that the THD of even the best transducers is typically in the order of 0.25% to 1%, the distortions of commonly used transducers mostly simply add harmonics, otherwise known as overtones, or multiples of main frequency, that do change the timbre/coloration of sound, yet are perceived as natural by the human hearing system.

The solid state amps introduce unnatural intermodulation distortions resulting in appearance of phantom sounds at frequencies (f1-f2) and (f1+f2), and these formulas are only that simple when only two major frequencies are present. With several major frequencies present at any given time in a typical recording (usually 3 to 12), the picture gets a lot more complicated.

Numerous phantom signals at effectively random and constantly shifting frequencies, appearing due to the intermodulation distortion, greatly confuse the human hearing system and make any music sound, well, unmusical. The sound processing neural circuitry tries to filter those frequencies out, thus consuming more neurotransmitters, depletion of which manifests itself as listening fatigue.

The solid state amp's THD is typically correlated with its level of intermodulation distortion. There are good theoretical reasons for that, but it can be also understood on a general level - the more linear and uniform over the frequency range the transmission function of the amp is, the less THD and less intermodulation distortions it will have.

Basically, the most significant source for both harmonic and intermodulation distortions is the same - amp's non-linearity - and it has to be reduced to "unheard of" levels (pun intended :-) for a solid state amp to sound right. This is an oversimplification, only correct as a first approximation, yet it does indeed depict accurately the dominant factor.

The high linearity is typically achieved with the negative feedback loop in combination with highly symmetrical amp design and very high open-loop amplification coefficient. Achieving this is expensive, as more stages of amplification are required and those stages have to consist of precisely matched components.

This task is much simpler if the amp power requirements are low, as designers can use operational amplifier chips, which achieve high symmetry and ridiculously high open-loop amplification coefficients by the virtue of their on-one-chip design.

That's one of the fundamental reasons why modern professional monitor speakers sound so good - they use multiple transducers, each powered either by a separate high-quality op-amp or a simple circuit incorporating one. 

The splitting of original signal onto frequency bands happens before that professional monitor op-amp, using active crossover, so that the op-amp doesn't have to work as hard as the amplification cascades of a typical discrete amp that has to drive multiple transducers through highly lossy passive crossover.

Corollary - a couple of professional monitors that cost slightly over $1,000 may sound as good and as loud as a combination of traditional audiophile-grade discrete amp and elite loudspeakers costing upward of $5,000. 

Yes, of course, those were my opinions. Yet by now you may have noticed that I have some background in electrical engineering and neuro-acoustics as well, so my opinions may have some merit after all :-)

In general, applying scientific approach to data gathering and especially data analysis is sometimes much trickier than it may seem at first. Blind testing using speakers that are behind a heavy cloth is a good example of an experiment where the systematic error is not well-controlled. Thus I don't have much trust in some pieces of what passes as "research" these days.

This isn't completely relevant but I was researching different sounding amps and came over this article (and a few others that are similar). This one doesn't have the most scientific layout but many other websites had similar posts if you want to google it. Can you tell the difference between Bud, Miller, and Coors? 

http://www.strandbrewers.org/reviews/blind98.htm

Sorry if it is a bit off topic but it shows how much sight plays into our perception.

Blind testing beer... I like the sound of that!

I get the feeling that after a few it's not really going to matter...   

Quote:

Originally Posted by DDVX 

This isn't completely relevant but I was researching different sounding amps and came over this article (and a few others that are similar). This one doesn't have the most scientific layout but many other websites had similar posts if you want to google it. Can you tell the difference between Bud, Miller, and Coors? 

 

http://www.strandbrewers.org/reviews/blind98.htm

 

Sorry if it is a bit off topic but it shows how much sight plays into our perception.

Correct me if I'm wrong, but they should have done it ABX instead. If there isn't an obvious and famous flavor to one of the brands, the testers may not have known what each brand was supposed to taste like, leading them to choose a favorite but not being able to pick what brand it is. To see if a difference was clear rather than to see if they knew what brands tasted like, they should have had 4 samples, one marked A and the others marked 1-3 or whatever, and they choose which number tastes most like A.

How did Harman International determine that their screen is acoustically neutral?

You can find all kinds of (mis?)information about all kinds of subjects, in print, and online.  You can find counterpoint opinions debunking the same.  Ultimately, as with this stuff, you need to make your own decision.  Just because you find it online and or in print does not make it fact.  As far as these "myths" are concerned, I'd suggest you compare yourself, using your own ears, your own music, your own room, and no outside influences.  If you can't hear differences you will have saved a whole lot of money that you can put towards actual music, or towards some other priority.  Kingstyles makes a good point - there's an entire industry that's been thriving for a long time based on the presumed findings by millions of people that there are actual differences that they are willing to pay for.  Based on fact or fiction many of those people have found their investments to be rewarding on some level. 

Quote:

Originally Posted by Prog Rock Man 

 

I agree, totally, which is why I wish anyone who wants to criticise blind testing should try it themselves. I have no issue with, as you say people finding rewards with their investments, so long as they realise they are buying into a brand/style/image and not any real improvement in sound.

I don't think we agree totally - I think it is absolutely, entirely irrelevant whether they realize what you suggest or not.  What is important is if they enjoy what they ultimately choose.  Why they choose it and enjoy it may not be something you nor I could grasp, but we can certainly empathize with the concept of "enjoyment". 

I would similarly think it entirely irrelevant for someone of faith to have knowledge that their God is not a scientifically provable fact.  If their faith makes their life fuller and more enjoyable and enhances their connection with people and with the world around them I'd say live and let live - who am I to judge or decree that science is the standard by which we all should live our lives?  I'd guess the majority of the people on the planet would have some cause to disagree on some level of reflection.  I'm not trying to drag this thread in that direction, God forbid (pun intended), but using it to illustrate a point.  Though hearts and minds may all be connected in some way, we are all quite different in the way we perceive the world, the choices we make, the paths we take.  As different as our fingerprints. 

It comes down to the age old subjective / objective argument for which there will never be any winner or right answer.