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What parameters should be measured to quantify differences between cable acoustic properties. - Page 2

post #16 of 37
What I am saying is that when you cancel two analog recordings by substracting them, 99 % of the difference comes from erratic time drift. Extracting a useful information from the result is like extracting the cosmic background radiation from the static on the TV.

Imagine that between the two recordings, you have a lenght difference of 1/44100th of a second. That is still an accuracy better than 10^-7 over a 5 minutes recording.
In the worst case, a 0 dB 22.05 kHz sine, the amplitude error will reach the complete 65536 steps of the 16 bits recording, since you get the next sample instead of the good one !
In order to cancel two signals with an accuracy of 16 bits over a 5 minutes recording, you need a timing accuracy of 10^-12 !

Therefore signal cancellation is not a practical way to detect any analog difference.

I know minute differences can be detected by analysis. I even detected differences between the direction of interconnects with the RMAA software, with cables that have no direction ! The 50 Hz hum was just differently picked, because I did not exactly replace the cables in the exact same orientation between the two recordings.

It is perfectly possible to measure the differences between two interconnect. They are mainly frequency response at 20 kHz (differences of about 0.01 dB), and 50 Hz Hum. IMD and THD are null, or at least completely masked by the ones of the DAC and ADC.
Both are way, way below audible thresholds.

Face it, there are NO measurable parameters in interconnects that have any relationship with their "sound". The only way out is blind testing.

As soon as some people who can reliably hear differences between interconnects begin to investigate this way, we can learn new things. So far, most testers were people who usually don't hear differences, or very little ones.
Grand X, in France, recently did some blind testing with a good perception of differences between cables. The test failed. His conclusions so far is that he doesn't understand why the differences change or disappear during the test, and he wishes to go on until he understands why.
One of the most interesting part in this ABX was that differences were clearly heard, but not when the cables were changed, even when the listeners knew the cable was not changed !
For example, after the presentation of X in the 6th trial, one listener asked to listen to the reference, then to the same random cable X again. Several people had the very clear feeling that the sound was no the same at all ! They changed their ABX answer for this trial, but were completely puzzled, because they did not understand why this X cable sounded like A (or B) when first presented, and like B (or A) when presented again.

That's an example of phenomenon that a listener can investigate in order to qualify the sound of cables. There are things to learn here.
post #17 of 37
Very nice post Pio2001.
There are certainly things to learn here. There is much more we don't know than we are aware of. And there are too many people that think they know it all...
post #18 of 37
Thread Starter 
I'm sorry but are you guys saying that the differences picked up by the listeners don't actually exist the physical sense? eg they cannot be picked up by analysing a recording of the sound as they are not physically there?

No offence but if thats is the case I am wasting my time discussing this with you guys.

My apologies if I am misinterpreting what you are saying.
post #19 of 37
Quote:
Originally Posted by Shark_Jump View Post
I'm sorry but are you guys saying that the differences picked up by the listeners don't actually exist the physical sense? eg they cannot be picked up by analysing a recording of the sound as they are not physically there?

No offence but if thats is the case I am wasting my time discussing this with you guys.

My apologies if I am misinterpreting what you are saying.
Well, for some people it has not been proven with 100% reliability -nothing is 100% reliable-, but differences are made up by the listener.

As explained on the article in my signature, if the listener has been highly influenced by the advertising/opinions, because he is "willing" to hear changes, or because due to the money he spent on cables he thinks there MUST be a difference, his brain will make him really believe there IS an audible difference, when in reality no change in the audible frequency has happened.

Why do some people like some cables more than others, if they are both well built? Well that has not been proven, but it might be something to do with the mental state of the listener, how he is feeling at the moment of listening, what he is expecting, etc... EDIT: It is rare, and I have not looked for it, that two members of this site that have bought the exam same cable and have not read anything about them, think they change the sound in the same way, if they have the same equipment. There can be very different "sound signatures" for the same cable.

I recommend you read the article in my sig. It is not the absolute truth, nor you will find it in people's opinions, but it explains quite well some of the parameters that would make a change in SQ.
post #20 of 37
Thread Starter 
Sure but with reference to the previous posts I was getting the impression they thought expensive cable has been blessed with some sort of unmeasureable 'magical' properties.

It is a pointless exercise to discuss a rational scientific experiment with someone who is not from a science background who has this sort of belief system. (That is the nicest way I can express what I'm thinking).

The measurement bit was not was this thread is about as this IS a staightforward exercise, any differences in the physical domain can be measured. I was postulating that additional parameters or just certain small differences that the ear is particularly sensitive to are not being taken into account, {added: when the test signals are being analysed}. - hence this thread.
post #21 of 37
Parameters can be measured Pio, the next step is using what has been learned about the JNDs of the human hearing system to determine whether changes in those parameters are audible.

At this point for most of the issues being discussed there's no objective, measured and scientifically rigorous data on the matter that I know of that proves cables can or do make a difference. In fact most would show that the differences that do exist in certain cases are well below any human's hearing capabilities that they are not issues, also suggesting the cables don't make a difference.

Another way to test it is the DBT instead of measuring various parameters about the cables. While inferring audibility from measurements is one thing, a DBT can prove or disprove whether the people available can hear the difference. That doesn't mean everyone hears the same although there are certain things I'm sure an audiologist would say are outside of reason and if you sample enough people with a DBT you can get a pretty clear picture.

What is known and proven is how easily human perception is affected by various influences like price or suggestions or opinions of others.

While I will say nothing shows that cables making a difference is objective fact, the subjective truth for many is that they do. Regardless of what causes that - real, measurable quantities (which do not support the idea of audible cable differences) or suggestion (psychological response affecting our perception) the thing that matters most to the end user is what they say they are hearing. Even if it is all in your head, it's still reality to you.
post #22 of 37
Thread Starter 
Quote:
Originally Posted by Pio2001 View Post
What I am saying is that when you cancel two analog recordings by substracting them, 99 % of the difference comes from erratic time drift. Extracting a useful information from the result is like extracting the cosmic background radiation from the static on the TV.

Imagine that between the two recordings, you have a lenght difference of 1/44100th of a second. That is still an accuracy better than 10^-7 over a 5 minutes recording.
In the worst case, a 0 dB 22.05 kHz sine, the amplitude error will reach the complete 65536 steps of the 16 bits recording, since you get the next sample instead of the good one !
In order to cancel two signals with an accuracy of 16 bits over a 5 minutes recording, you need a timing accuracy of 10^-12 !
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If you think the human ear can hear better than 1/44100th second and 16 bits (Which I don't) why dont you record analogue and just use an analyser with a sampling rate of 200 million samples/s? Would that be accurate enough for you?
post #23 of 37
Thread Starter 
Quote:
Originally Posted by csroc View Post
Parameters can be measured Pio, the next step is using what has been learned about the JNDs of the human hearing system to determine whether changes in those parameters are audible.

At this point for most of the issues being discussed there's no objective, measured and scientifically rigorous data on the matter that I know of that proves cables can or do make a difference.
I'm so glad you said that I thought I was going nuts.

Yes, the difficult bit determining which differences are relevent, where relevent means what can be determined by our superhuman listeners as 'making a difference to the sound'.

That is why I believe it is important to catagorise these differences so they can be turned into specific descreet listening tests, again using rigorous lab conditions.
post #24 of 37
Quote:
Originally Posted by Shark_Jump View Post
If you think the human ear can hear better than 1/44100th second and 16 bits (Which I don't) why dont you record analogue and just use an analyser with a sampling rate of 200 million samples/s? Would that be accurate enough for you?
I was not talking about sample rate, but about Uncle Erik's idea to overlay the two recordings in order to "see the difference". This is not possible in practice because of time drift. When you sample-align the beginnings of your recordings, the ends are out of synch, and conversely.

Actually, it just occured to me that it might work if the DAC used for playback and the ADC used to record are slaved to the same clock.
post #25 of 37
Quote:
Originally Posted by JaZZ View Post
That's a question nobody can answer. There's a cable-measuring test going on in the «cables» forum, with no significant result so far -- and I haven't seen a comparison which would show any kind of (universally accepted) significance. So the verdict is easy: Cables make no audible differences. At least to those who haven't heard them.

This thread could just as well be closed -- the question has been asked multiple times before, logically with no definitive answer, but a lot of personal attacks instead.

As much as I'm interested to see any data on the subject, I have more or less given up on it. It's not that cables don't show measuring differences, but they are tiny and don't provide a hint which of them could cause which audible characteristic. Nevertheless to me cables are a reliable tool for fine-tuning my system. I could just decide they don't do anything, the differences are imagined -- but what would I gain by doing so? The effects are absolutely persistent, so it's as good as if they were real.

Of course I'm joking a bit, because I still think they are real. No failed DBT would convince me of the opposite (I've passed a blind headphone-cable test). During my speaker-builder «career» I've done a lot of non-blinded comparisons between different crossover-network tuning variants. The measuring differences with the components were minuscule (some of them within less than 1‰ -- let's say 4.782 vs. 4.778 μF). It wouldn't have been practicable to do them blinded, let alone DBT -- imagine 20 or more different tunings within 1 hour. Anyway, according to the hegemonic objectivist philosophy they have been useless. Personally I don't think so. And I suppose that most speaker builders use the same tuning method -- with success.
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The only reason, or better, maybe one of them, this section of the forum exists, is to ask these kind of questions and try to get the answers, otherwise we are facing anecdotical experiences and voodoo...

The problem is that nobody till now had tried to be objective and try prove what actually make or not those differences, ones because they are convinced of the differences and do not need to prove any further, the others for the same reason but in the opposite way...But what about the ones who are in the fence, trying to see if they can see the light, or amybe to see to what extend ones or the others have the reason or not...

There was a cable comparator that a cable manufacturer did some time ago, WIREWORLD, they actually recorded using different cables in the same exact setup, same track, just exachangin the IC's, and they used a huge spectrum, from Monster, Blue Jeans, to Valhallas, and let me tell you that if the differences exist, they should be there at least, I have the CD and honestly to my rusty ears if there is any diference is so minimal that is almost none (to the ears) so I opted to save myself a few bucks in cables, order BJC and invest in other parts of the system that will make a more noticeable difference...
post #26 of 37
Thread Starter 
'Actually, it just occured to me that it might work if the DAC used for playback and the ADC used to record are slaved to the same clock. '


Yes, good idea. Another method is to move the phase of signals till you get a reasonable match. For example you can add a high frequency pulse (say 100Khz timing signal pulse) and phase shift one of the two signals on the scope till they match each other.

Remember that test measurment and playback instrumentation can have resolutions many times higher than Hi Fi equipment that you appear to be using as a reference. I once worked testing frequency response of small gas turbine compressor blades, we were were recording and measuring responses much higher than human hearing - in the 40Khz-50Khz range. (If yr interested google Kistler or Kulite probes on the net)
post #27 of 37
Thread Starter 
Quote:
Originally Posted by csroc View Post

While I will say nothing shows that cables making a difference is objective fact, the subjective truth for many is that they do. Regardless of what causes that - real, measurable quantities (which do not support the idea of audible cable differences) or suggestion (psychological response affecting our perception) the thing that matters most to the end user is what they say they are hearing. Even if it is all in your head, it's still reality to you.
I have to disagree with this statement.

I have read on this website of someone with a $250 system raising the subject of spending an equivalent sum on his power cable. (apologise as I cannot recall the thread, however I am sure most can recall similar discussions).

To me this example has less to do with 'perceptions' as to do with somebody being mislead, possibly by people with less interest in his listening pleasure and more interest in their own hip pocket.

I think what I am proposing here is worthy even if just that one guy can make a more educated decision about his purchase
post #28 of 37
Quote:
Originally Posted by csroc View Post
the thing that matters most to the end user is what they say they are hearing. Even if it is all in your head, it's still reality to you.
I think that this is a very limited point of view.

What would you say if you improve your stereo until you are satisfied with the sound, and someone secretely degrades your work by removing tweaks, cables, etc, replacing them with standard devices instead of the ones that your bought in order to improve sound. If the difference is not in the device, then you shall still hear the right sound in your head.
Would you say then that it has really no importance if your cables, stands, capacitors etc, are gone, as long as you hear what you like, BUT that it was nonetheless necessary to buy them in order to improve the sound ?

This point of view also justifies the work of some brands that rebadge low end CD players or amplifiers into fancy-looking cases, and sells them 10 or 50 times the initial price. If all that matters is what we hear in our heads, then this practice should be considered as honest.
post #29 of 37
Quote:
Originally Posted by Shark_Jump View Post
I'm sorry but are you guys saying that the differences picked up by the listeners don't actually exist the physical sense? eg they cannot be picked up by analysing a recording of the sound as they are not physically there?

No offence but if thats is the case I am wasting my time discussing this with you guys.

My apologies if I am misinterpreting what you are saying.
If you think that's weird, Bell's Theorem is really gonna bake your noodle
post #30 of 37
Copied from a parallel thread:

Some years ago a friend and I made some listening tests with the GaborLinks (a review in Portuguese here).

These elements are meant to simulate the skin effect in a cable -- in different intensity and shape. At the same time it's said to be able to compensate for phase distortion and group delay caused by cables and the entire signal path, hence to recreate a coherent phase response throughout the frequency spectrum. So far the theory.

We listened to my friend's setup with homemade speakers using (no-name) dual-cone fullrange drivers with paper membranes -- nothing spectacular in terms of sound quality or resolving capability, but also not heavily coloring. None of us was placed in the sweet spot between the speakers, and we had different listening angles.

Even with these unfavorable conditions we both could hear significant differences with the different GaborLink elements in the signal path. And astonishingly we agreed to 99% in our judgements about which of them were favorable to the sound and which weren't, to which degree and in which respect. The differences indeed reminded me of cable sound.

So I'd recommend to give the skin effect/phase distortions a try when it comes to measurings. Not in the form of phase measurings, but rather in the form of complex waveforms -- such as a cymbal crash or an excerpt of it, resp. --, if possible analogue or in high-resolution digital (96 or 192 kHz sampling rate) for better signal-shape discrimination/identification due to the avoiding of transient corruption by the antialiasing filter.
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