Questions Regarding Power Cable ABX Test

DarqueKnight

An often quoted (by naysayers) article on power cable ABX testing is here: Secrets of Home Theater and High Fidelity Power Cable ABX Test

There are couple of things about the test that give me pause for reflection:

1. A valid test, or any evaluative procedure, must evaluate a thing under the conditions it is most likely to be used. Blind trials are appropriate for some things and inappropriate for other things. Blind trials are appropriate for the evaluation of medicine when the medicine is administered under conditions in which a patient would take the medicine on their own in a non-supervised environment.

2. Every audio ABX test I have read in audio publications uses a setup that in no way reflects the way a consumer would listen to their audio system in their home.

Question 1: Why do some people cling to a fallacious, inappropriate test? This would seem to undermine their credibility.

I'm all for test and evaluation, provided the test is appropriate to the thing being tested.

This widely accepted ABX test was administered in a way that demonstrates an ignorance of the way stereo works. The picture below shows the participants for the ABX test referenced above:

Figure 1. Secrets of Home Theater and High Fidelity PC ABX Test Participants. Are any of these people
audiophiles? Is this the way they listen to music on their audio systems in their homes? Really?

Notice that the listeners are positioned in three rows with two to three persons per row. It is my understanding that the critical evaluation of a high fidelity stereophonic audio system must be done from the "sweet spot", i.e. the spot directly between the speakers where the stereo image is optimum. Unfortunately, for critical listening, only one person can occupy the sweet spot at a time.

The gentleman in the blue shirt appears to be in the sweet spot. However, we can reasonably deduce that his stereophonic perception was negatively impacted by the gentlemen on either side of him. One can only wonder how much imaging, detail, clarity and whatnot was lost due to sound reflecting off the heads of the two men on either side of the first couch.

Do this test if you have a preamplifier that can be switched by remote control from stereo to mono: Listen to a music selection which has excellent stereo separation and then switch back and forth between stereo and mono. When I do this test I find that musical details that were vivid in the stereophonic rendering disappear in the monophonic rendering.

Look at the men in the second and third rows. What kind of stereophonic image, if any, do you think they were getting? Collapse of a stereophonic sound field can cause lose of detail (information). Doesn't your heart ache for the poor soul in the green shirt on the third row?

Question 2: Stereophonic playback is a fragile illusion. When an evaluator is sitting in a compromised, "squashed", and no longer truly stereophonic sound field, is it reasonable to expect that said evaluator would provide accurate data?

Question 3: Would not it have been better for each participant to sit in the optimal sweet spot in succession and then record their listening impressions? The way the test is rigged in Figure 1, each participant is hearing a very different rendering of the music based not only on their individual hearing biases, but also on their compromised, sub-optimal listening position.

I get a wide, deep, holographic sound stage from my two channel audio system when I am seated in the stereophonic sweet spot. However,

1. If I stand up at the "sweet spot" listening position, I lose some audio details.
2. If I stand or sit along the wall behind the "sweet spot" listening position, I lose some audio details.
3. If I sit or stand to the far left or far right of the "sweet spot" listening position, I lose A LOT of audio details.
4. Is someone is seated next to me while I am in the "sweet spot" listening position, I lose a little or a lot of details, depending on the size of the person. A person sitting next to me also diminishes the tactile sensations coming from the sound stage.

Figure 2. "Can We Hear Differences Between A/C Power Cords?" - No, I don't think you can.

The referenced ABX article is titled "Can We Hear Differences Between A/C Power Cords?". The first time I saw the article and the picture of the test participants, I thought it was a tongue-in-cheek parody because obviously, you cannot do a serious, valid evaluation of differences in stereophonic audio system gear with a compromised stereophonic sound field.

Figure 3. The wizard is hiding something behind the curtain! :eek:

Figure 3 shows that the audio system and the power cables under evaluation were hidden behind a thick fabric curtain, which extended into the speaker plane. Putting a thick sound absorptive panel (like a rug) on a hard floor in front of the speakers is usually a good thing. Putting a thick sound absorptive panel (like a curtain) between the speakers is usually a no-no and bad ju ju.

Question 4: How many of you do critical listening with a curtain along the front plane between your speakers? I've never tried this, but I do not think I would like it.

Figure 4. Some seriously nice high end gear was behind this curtain.

It was a pity the test participants heard a crippled and compromised rendition of what such high resolution gear is capable of. Curtains in the speaker plane and multi-row seating? For a critical audio review? Really?

Summary

An ABX test was conducted purportedly to evaluate audible differences in power cables.

An absorptive curtain was placed in the speaker plane between the speakers.

The evaluators were seated in a manner which is highly detrimental to the the realization of a stable, focused and detailed stereophonic sound stage.

The participants in this ABX test achieved results that were statistically similar to guessing, which indicated that there were no actual audible differences among the power cables tested.

Special Request

Please remain calm, civil and informative in your responses. This is a serious inquiry regarding one of the pillars of power cable naysayer science.

LuSh

In the time you took to write this thread you could have probably listened to a CD. Probably time better spent. Take a deep breathe and step away from the computer.

DarqueKnight

Actually, I wrote this on my laptop PC while sitting in the SDA sweet spot listening to an SACD.

I think I am best qualified regarding how to spend my recreational time...but thanks for the suggestion.

hearingimpared

Setting subscription to this thread as I'm too tired to read it now but am very interested in it.

jinjuku

Is it possible that with the seating distance that the participants were within the on axis listening field of the speakers? Just hazarding a guess.

Even with my system I can sit a seat cushion left or right and the imaging is still fine. Due to the distance I sit the deflection(?) isn't changed to much. Get too much off axis and for sure I have problems.

Even the guy/s in the sweet spot couldn't pick the cable out. Personally I would love for a $99-$150 device of any stripe make a clear, distinguishable, marked, audible improvement. Who wouldn't? Heck I am looking at an MIT outlet to try and strangle the almost in-audible hum from my sub due to the PJ being on a different circuit.

jinjuku

BlueFox wrote: »

For a few dollars more, MicroPoints and TriplePoints. Even a deaf person could tell there is an improvement.

http://shop.mapleshadestore.com/products.asp?dept=100

The server that hosts all the lossless music is in the basement. Should I put the feet there?

hearingimpared

The ABX test are flawed, always have been for audio testing. The points you make above Raife are all valid and increase the error rate of the participants.

The most important point for me against ABX testing is as you stated above they are not a replica of how one listens to music in their own environment.

I'll take it a step further. When I am A/Bing a component, cable, or music for that matter, I never switch back and forth between the two items being tested. Rather, I listen to each change for a period of time, that time can vary between one hour, one day, or one week, then I switch to the "other" being A/B'd. Then after the 'appropriate' amount of time i.e., the same amount of time given the previous piece I switch back to the original and then repeat. All the while, taking notes and comparing them.

It is beyond me, especially something as subtle as cable testing can be, how one could switch back and forth for a minute or two and get a an accurate feel is beyond me.

Unless there is a dramatic difference in the components being tested, a quick switch between the items being tested is useless.

For example, I had bi-amp'd my 1.2TLs when I had Adcom 565 mono blocks and a Parasound HCA 1000A stereo amplifier. Here's the link http://www.polkaudio.com/forums/showthread.php?t=50391. I had become so accustomed to the 565s only powering the 1.2TL that when I did the biamping there was such a dramatic improvement that I had no need to switch back to the original configuration. This was because I had spent so much time critically listening to the original configuration that the dramatic improvement was glaring because I was listening so long to the original configuration and took notes, that when the bi-amp'd configuration was in place and I immediately noticed a difference I went back to my notes afterwards and compared the two; the original configuration and bi-amp'd configuration and my notes substantiated what I was hearing. This was indeed a case of a dramatic change that would be evident in switching quickly (which in this case would be impossible) back and forth.

Another example of the positive influence of long listening sessions being a necessity as opposed to short switching back and forth, is when I purchased a Raysonic CD 168 tubed CDP. The original configuraton was an Oppo multi-format disc player used as a transport going through a $4000 dollar Timbre DAC. One would think that this configuration would hands down beat a $2500 CDP. Not so. After being familiar with the original configuration, I switched to the Raysonic. I immediately heard a dramatic improvement in almost every category of subjective stereo sound. I didn't need to switch back but I did. It was a glaring improvement. When I compared notes of the two configurations, my notes supported this finding.

I could have saved myself $2500 as the Raysonic was a loaner from a brick & mortar store which I could have returned if I didn't like it IN MY RIG. I also would have saved myself the pain in the **** of selling the Timbre DAC and OPPO at a loss. So I had no financial motivation to keep the Raysonic. My wife noticed the improvement right away of the Raysonic over the OPPO/Timbre DAC from the get go and stated, "get rid of the OPPO/Timbre DAC as the Raysonic sounds much more like your turntable." The turntable is what I use as a baseline to compare digital sources such as a CDP and an SACD.

A third instance was when I purchased five sets of MIT Shotgun S3 ICs and replaced the original ICs which were Ben's Silver ICs which BTW I thoroughly was enjoying in my rig. The change and improvement in sound was dramatic AFTER burning in the MITs. I switched back and all the improvements were gone. However, note that I had been listening to Ben's cables for at least a year. My notes again, reflected the improvements. Now I could have easily saved myself $1500 and kept Ben's cables in place but there was such an improvement and I loved those improvements that I kept the MITs which I could have returned because they were still in the 30 trial period. I loved the sound of Ben's cables so much that I replaced all the ICs in my HT rig which brought a sparkle, imaging and soundstage improvement to the HT rig which I typically don't listen to critically.

To summarize; I don't see how it would be possible to do accurate ABX or simple A/B testing out of my element i.e., my own rig, in my own sweet spot (which is rather small and narrow) switching back and forth between components with only a one or two minute time limit on each item.

How one can make an accurate assessment of any piece of gear in an unfamiliar environment, using unfamiliar gear, with being out of the sweet spot and all the other elements present is said ABX test especially power cables where the differences (in most cases sublte) in cables can be simply as different as a lower noise floor, again, is beyond me.

This is why I believe the ABX test posted by many cable naysayers is invalid and is biased towards there not being a difference in ANY piece of gear let alone a cable.

treitz3

This widely accepted ABX test was administered in a way that demonstrates an ignorance of the way stereo works.

That's signature material right there, folks.

hearingimpared

This widely accepted ABX test was administered in a way that demonstrates an ignorance of the way stereo works.

treitz3 wrote: »

That's signature material right there, folks.

Can I get an AMEN!!!;)

tonyb

Personally,I don't understand why we still feel a need to verify the whole cable thing one way or another. Experience is the baseline.

DarqueKnight

I agree that experience is the baseline.

However, we must be mindful of the fact that some new people coming into the hobby will not see the value in personal experience and will make equipment decisions based solely on the massive amounts of information and mis-information freely available on the Internet. A lot of them won't stop to critically evaluate the information that is offered to the public and they will just accept it at face value because it appears to come from a credible source. The article which is the subject of this thread is a prime example.

NJPOLKER

DarqueKnight wrote: »

I agree that experience is the baseline.

However, we must be mindful of the fact that some new people coming into the hobby will not see the value in personal experience and will make equipment decisions based solely on the massive amounts of information and mis-information freely available on the Internet. A lot of them won't stop to critically evaluate the information that is offered to the public and they will just accept it at face value because it appears to come from a credible source. The article which is the subject of this thread is a prime example.

This is the reason I am so happy Ken Swauger put me on to this forum a few years ago. I was middle age and dumb now I am middle age and poor :mad:
Thanks Raife for being a great help to all of us.
Drew

DarqueKnight

Psychologists have done a lot of research into test development for the evaluation of sensory stimuli (sights, sounds, tastes, smells, tactile sensations).

It is interesting to note that the psychological literature does not seem to support the use of blind tests as a valid evaluative tool for sensory stimuli. Two widely respected texts on evaluation of sensory stimuli are

1. "Sensory Evaluation Techniques" by Morten Meilgaard, Gail Vance Civille, and B. Thomas Carr.

2. "Consumer Sensory Testing For Product Development" by Anna V. A. Resurreccion.

"Sensory Evaluation Techniques" describes every test (and there are many) used by psychologists to evaluate sensory stimuli. Blind testing is conspicuously absent. Indeed, only a cursory review of the psychological literature revealed that blind tests for sensory stimuli are not scientifically accepted by the professionals in the field. From what I have been able to gather, the prevailing thought among psychological professionals is that there is too much random variation (bias) in the way individuals perceive and process sensory stimuli. Therefore, tests to evaluate sensory stimuli must have a degree of rigid control which is unavailable in blind trials.

Now, we have an interesting situation: When we read naysayer literature, we find that the prevailing thought is that there are no differences in cables or, if there are, the differences are beyond the threshold of audibility. Furthermore, many of them state that if such differences really did exist, they would be validated by blind trials.

When we read the professional psychological literature, we find that blind trials for sensory stimuli (e.g. the sounds produced by an audio system) are not scientifically accepted evaluation methods.

In summary, we have a group screaming for "scientific" proof, but they want such proof to be based on results from a test that is scientifically unaccepted and proven to be ineffective for the stimuli to be evaluated.

Such good science.

concealer404

The one biggest flaw in this test?

I don't listen to my system blindfolded, or with anything covering up the components. So why would i test like that?

Game. Set. Match.

Placebo Effect be damned. If the placebo gives me more enjoyment, then so be it. Who even cares?

Huck344

Great write up! I agree with others as well. Actual experience is most important. I had no clue whether power cords would make a difference. But, I probably leaned to the side of they wouldn't make a difference. After trying different cords, I felt (heard) a difference. So, in my book, they make a difference. Those who base their decision on written materials (flawed test or not) are robbing themselves of actual true life experience, which is a true shame because this hobby is all about "the experience."

hearingimpared

Very interesting Ray that they don't do any blind testing in sensory tests.

Having diminished hearing in my right ear I've been through dozens and dozens of hearing tests throughout my life. In each test I was able to see the tester moving his hands and adjusting controls but that didn't seem to make any difference, as far as the tester was concerned, as to the outcome of the test.

I wonder if I was blind folded or couldn't see the tester and associated equipment if that would in any way affect the outcome of the tests even though the tester was behind the gear and I really couldn't see him changing any frequency dials or hitting a button that just sent the signal. IMHO I don't believe it would. I either heard the signal frequency or I didn't.

hearingimpared

Huck344 wrote: »

Great write up! I agree with others as well. Actual experience is most important. I had no clue whether power cords would make a difference. But, I probably leaned to the side of they wouldn't make a difference. After trying different cords, I felt (heard) a difference. So, in my book, they make a difference. Those who base their decision on written materials (flawed test or not) are robbing themselves of actual true life experience, which is a true shame because this hobby is all about "the experience."

BINGO! AND that's not to mention the training your ears get as to learn finer attention to detail with your ears over time.

treitz3

Out of all of the hundreds of threads that go 6,7, 8 or more pages deep because the "nay-sayers" come out of the wood works....

I really wonder where they are and what they have to say about this thread. So far, all I've heard is crickets from them. What's up with that?

hearingimpared

Hard to argue with sound reasoning and real science!!!

steveinaz

I think the biggest flaw in the test is lack of system familiarity. There are times when changes take me days to really appreciate the overall impact.

hearingimpared

steveinaz wrote: »

I think the biggest flaw in the test is lack of system familiarity. There are times when changes take me days to really appreciate the overall impact.

nail, head, hammer!!!!

treitz3

steveinaz wrote: »

I think the biggest flaw in the test is lack of system familiarity. There are times when changes take me days to really appreciate the overall impact.

All due respect gentlemen but I can not really see that as an excuse or flaw. I'm not by any stretch of the imagination saying I have a golden ear but I hear the most subtle of changes in a system I have never heard before.

Perfect example would be down at Ted's pad for one of the PF's. Joe, you might have been there for this, I can not remember. Anyhoo, we were upstairs listening to the Manley Stingray, a pair of SDA's [both of which I had not heard before] while A/Bing the Rega Apollo to Jesse's hot rod Jolida. After hearing the Rega, I could tell within a few seconds that I preferred the Jolida. We went back and forth a couple of times with the two CD players.

When someone had asked what differences I heard in the two players, I spoke for a good two to three minutes explaining around 20 different aspects of the playback reproduction and the differences between the two players. There were about 23 or so people in the room when all this went down and most of them heard me.

Point is, I had never heard any of that system before with the exception of a PC I brought along with the Rega Apollo I had had for about a month or two at that time. It was the first time I heard MIT's as well.

hearingimpared

treitz3 wrote: »

All due respect gentlemen but I can not really see that as an excuse or flaw. I'm not by any stretch of the imagination saying I have a golden ear but I hear the most subtle of changes in a system I have never heard before.

Perfect example would be down at Ted's pad for one of the PF's. Joe, you might have been there for this, I can not remember. Anyhoo, we were upstairs listening to the Manley Stingray, a pair of SDA's [both of which I had not heard before] while A/Bing the Rega Apollo to Jesse's hot rod Jolida. After hearing the Rega, I could tell within a few seconds that I preferred the Jolida. We went back and forth a couple of times with the two CD players.

When someone had asked what differences I heard in the two players, I spoke for a good two to three minutes explaining around 20 different aspects of the playback reproduction and the differences between the two players. There were about 23 or so people in the room when all this went down and most of them heard me.

Point is, I had never heard any of that system before with the exception of a PC I brought along with the Rega Apollo I had had for about a month or two at that time. It was the first time I heard MIT's as well.

Yes Tom, I remember, and that just proves one of my points I posted above about dramatic changes. The more subtle changes still requires time to identify however.

Face

hearingimpared wrote: »

Yes Tom, I remember, and that just proves one of my points I posted above about dramatic changes. The more subtle changes still requires time to identify however.

I agree.

treitz3

hearingimpared wrote: »

The more subtle changes still requires time to identify however.

That, I can agree with.

Many of the things I had mentioned were subtle changes though. There were some people in the room that swore the two sounded the same. I will say this though, out of all of the folks in the room, I was one of the few that was relatively close to the sweet spot behind the couch.

Conradicles

I know it has much to do with the gear being used as well. In my system, no audible differences were heard by me when trying an upgraded power cord on a tube buffer, and on my old Processor.

But when changing interconnect and speaker cables, my system is decent enough for me to hear sonic differences.

In my mind (just in my tiny mind), here is the "audio food chain" of pieces that make the biggest differences in audio reproduction top to bottom (top being most substantial):

speakers
DAC/Source
Pre
Power Amp
Interconnects
Speaker wires/cables
Power cords

Nice write up DK as always. Peace.

hearingimpared

treitz3 wrote: »

That, I can agree with.

Many of the things I had mentioned were subtle changes though. There were some people in the room that swore the two sounded the same. I will say this though, out of all of the folks in the room, I was one of the few that was relatively close to the sweet spot behind the couch.

I was kneeling behind the couch in back of you. Was that when your eyes started to go in two different directions or were you still within the plane of reality?:D;)

hearingimpared

Conradicles wrote: »

I know it has much to do with the gear being used as well. In my system, no audible differences were heard by me when trying an upgraded power cord on a tube buffer, and on my old Processor.

But when changing interconnect and speaker cables, my system is decent enough for me to hear sonic differences.

In my mind (just in my tiny mind), here is the "audio food chain" of pieces that make the biggest differences in audio reproduction top to bottom (top being most substantial):

speakers
DAC/Source
Pre
Power Amp
Interconnects
Speaker wires/cables
Power cords

Nice write up DK as always. Peace.

Right on the money pal IMHO! Although ICs and Speaker order can be switched depending on the quality.

steveinaz

Exactly, bravo. IME, cable changes are extremely subtle--albeit noticable in most cases.

DarqueKnight

treitz3 wrote: »

Out of all of the hundreds of threads that go 6,7, 8 or more pages deep because the "nay-sayers" come out of the wood works....

I really wonder where they are and what they have to say about this thread. So far, all I've heard is crickets from them. What's up with that?

Tom,

Please be patient. You know it takes time to search Google, Roger Russel and the Audioholics archives for the appropriate response.

Thank you for waiting.

DarqueKnight

hearingimpared wrote: »

Very interesting Ray that they don't do any blind testing in sensory tests.

Having diminished hearing in my right ear I've been through dozens and dozens of hearing tests throughout my life. In each test I was able to see the tester moving his hands and adjusting controls but that didn't seem to make any difference, as far as the tester was concerned, as to the outcome of the test.

I wonder if I was blind folded or couldn't see the tester and associated equipment if that would in any way affect the outcome of the tests even though the tester was behind the gear and I really couldn't see him changing any frequency dials or hitting a button that just sent the signal. IMHO I don't believe it would. I either heard the signal frequency or I didn't.

Medical scientists do use blind and double blind tests to measure sensory response as it pertains to the actual electrical response of nerves, just as blind trials are used in the evaluation of the effects of drugs on the body. In the case of hearing tests, it is well understood how humans might react to a particular test sound. Other things, such as the limits of audibility for a particular test sound are also well understood. With medical trials, a particular stimulus either is or isn't there and medical scientists can measure accordingly and make accurate evaluations.

When you move from the realm of measuring actual nerve response to measuring how the mind interprets sensory stimuli, blind tests present some problems and other types of tests are more appropriate. This is particularly true with illusory stimuli such as a stereophonic sound field. Different people react to illusions in different ways and it is difficult to quantify the wide variation in individual response to illusory stimuli.