how can a line cord affect frequency response ?

Metro04 - As an educated EE, I clearly do not have the experience today to begin a scientific or engineering investigation on the matter for which you so very much want definitive answers. But I am not sure we are there yet anyway.

As advanced as our semiconductor and software industries have become, they still fall very short of the ear/brain processing to analyze sounds and therefore music. How and where do we even start to develop processes and systems to identify those sonic attributes that the ear and brain immediately tell us what is the real piano, what is a close simulation or what does not come even close? It's not only frequency or phase response analysis. Music is not this simple to quantify. If Mrtennis or anybody else requires these answers to get confirmation that differences do/don't exist, I suspect he is going to be waiting a long time.

Some of the most brilliant engineers are working on the latest developments of digital systems. And the test equipment for these systems has to be even more precise. And yet, in the final analysis, when I hear digital music, as enjoyable as it can be, my brain immediately tells me something is very wrong. Do we have the ability today to measure and quantify this? And if not, how can we expect the industry to provide a solution sheet with all the answers to explain why I can hear that power cable A affects an amplifier differently than power cable B?

There are events when I can not hear differences between some cables in certain links of the chain; this is good news as it leaves money in my pocket. And when there are differences, the more expensive product is not always the one I prefer. Again, good news as it saved me the expense. But there are times when I discover a cable or any other component for that matter that brings on more abc or xyz; it gets me that much closer to the musical performance. It's a win situation in any of these cases.

If we go into the audition with a seeded mind that we will or will not hear a difference, we have to be prepared to accept that the outcome could be different. And this is independent of any survey, poll, testing, etc., done by any other person or group who have documented that cables in fact do or do not make a difference.

I am clearly no self-tauted audiophile. And I am not trying to provide unverified testimonials either. I simply shared my experience that this closed-minded enginner let his ears be the factor vs. a printed technical report to determine that such differences do or do not exist. If one person can hear that differences exist, then they do. And that person could very well be a third party.

As an engineer, I know how easy it is for data to be "presented" in a way that would cause anyone to initially come to any conclusion. And how many of us have access to the facilities to prove or disprove such claims? We rely on others to do this. So this too is all based on faith.

As Mrtennis reported, "hearing is believing, either i hear a difference or i don't hear a difference. at this point it's an anecdotal report which cannot be verified". But Mrtennis, as any of us who are just another citizen of the larger collective, reading a report is believing, and often neither you nor I can verify such. Thank you, but in the case of audio cable differences, I have more faith in my own ears.

John

if experience, then induction and opinion. if premises, then logic, deduction and knowledge.

regardless of what is said on this or any other discussion forum based upon experience, it can not be knowledge.

there is a probability that one does or does not hear a difference. the probability is unknown and there is no proof that a difference exists or does not exist.

if 2 people are in a room listening to some component comparison, one may hear a difference and the other not. this disagreemnet does not mean that there is or is not an intrinsic difference between the component. such a statement wwould have to be based upon knowledge and hence certainty.

however knowledge does not apply in that situation.

so, it all boils down to an opinion. a perception is also an opinion. people have different opinions. opinions are neither true nor false.

the purpose of this thread is become apprised of an explanation, more out of curiosity.

what i said about verification is true. there is no definitive verification of a perception. one perception does not confirm another. you can have 1000 perceptions and 1000 stereo systems. there is no way to know what is going on. it is all conjecture and speculation.

it is the exchange of these speculations and conjectures that makes for a lively discussion. it is enteraining and stimulating.

Better watch out guys and carps, Mr. Tennis's mechanical froggie is loose again in the audio pond with all its juicy and elegant sophistries. Before you know it he'll have you all wrapped around his magical pingponging fingers!

My Friends,
If any of my posts came across as arrogant or whatever, I am sorry. I am a music lover and audiophile, but alas, I have a degree in EE. That being said, having an EE degree does not automatically make someone an authority on power supplies and audio amplifiers. There are many paths one can take in this field but designing high performance audio amps, for instance, is a rare path indeed. My job involves digital designs with FPGAs for software radios, but my real passion is the analog stuff.

Although I am in the more objective camp, I have never stated that power cords can not make a difference. Rather, if you follow my previous posts, you can see I made a feeble attempt to describe how such a thing might be so.

One thing that I will never give up is my fundamental belief that if a real change is heard, however subtle, and repeatable, say between one power cord vice another, then there must be an underlying electrical change to manifest such sonic deltas.

If I did not believe this, then it really does boil down to faith in something else.

I do believe that there are material-electrical differences among pcs, and if in the right high resolution system with great acoustics, then these deltas may manifest. I think this can and does get out of hand and folks have to be somewhat realistic about expectations.

The longer I think about this, the more i'm inclined to believe that it's not simply reducible to the large amount of romex, nor the junction box, nor the long lengths from the step down xfrmr on the pole a bazillion feet away, nor the miles of 100 kV lines back to the distribution station. No. It must be the interface to this network. Why/ how I do not know yet but i have some ideas.

I listen to music alot, but I also love to measure things. I love to understand the physics behind something. In my view one reinforces the other.

A basic experiment to test currents on the ac-line:
A high power series resistor with the hot lead. The resistance will have to be low and this is not ideal, but it could work. A safe box of some sort will have to house the plugs and power resistor.
A basic ocsilloscope with a differential probe across the resistor (do not use the ground clip as you will be connecting the hot directly to ground via the scope cable--not good).
A test signal, like some continuous tones ala stereophile cd-2. Of course you need a trigger for the scope. Simply use the 60 hz ac line setting. This way you capture the events you want to see based on the power cycles of the ac.

You plug your amp pc into the thing you fabricated that houses the power resistor. Fire up the amp.

At this point, with the volume low, you might see some activity on the scope that relates to the charging of the filter caps, aka 120 hz (full wave rectifed).
If you can trigger the scope just right,and play with the time base, and vertical gain, sample rate, etc i bet if you crank up the input signal you will see, at the peaks, fluctuations that are directly correlated to the amplified signal.
Here is where i think power cords can make a difference.
The current is pulled sharply from the power amp at these peaks. We know that abrupt changes indicate high frequency. This is direct from theory and confirmation over hundreds of years.
(This IS not equal to whatever high frequency content in the signal to be amplified)

This is one fairly simple test that can be run. I currently do not have a working personal scope and probe of reasonable quality. I would love to do this however.

Of course this may be all wrong, but I like to offer possibilites to understanding our beloved hobby.

Later!

mr g, i will repeat what i said to others. stop taking yourself, the music, the sound so seriously. you resort to argumentum ad hominem instead of critiquing what i say.

your supercilious attitude is one reason why people think an audiophile needs a therapist.

if you lighten up your blood pressure may go down.

i must admit, i enjoy your british humor, it is so biting and civilized, but as a lawyer, i'd bury you in court.