IF Power cables make a diffrence then why not? - Page 45

Originally Posted by mcnarus

Jesus H. Christ. Are you unfamiliar with the concept of level-matching?

Ahh, so you admit there would be a need to level match to get the system with two different cables sounding the same? Sounds like a detectable performance difference to me.

Originally Posted by Joe Skubinski

Most dynamic loudspeakers have a decent off axis response, and we're talking about being 6-8 ft apart, so long as you are in front of them they will image. You of course do not necessarily have to get as close as possible, but to me it helped to exclude the room and find the minimum.

Originally Posted by rnrn

Did you do blind testing with different cables and different people to make sure there's no bias?

Originally Posted by cavu

That should be DOUBLE BLIND testing so no-one involved in administering the test knows which item is active at any point in time.

Originally Posted by jpjibberjabber

It sounds like you might think there's a difference to be had. You just don't know what that difference-maker is, so instead of acknowledging that fact, you team up with your e-buddies and ridicule.

My advice if you don't know the answer to something is to not laugh at someone that is asking the question. They might not know either, but are at least trying to find some answer.



Hate to quote the entire post, but this is very good. I couldn't have said it better, although I do think one can improve response with better optical fiber materials. That can be a minor thing though, and it's nice to have another person with hands-on experience. Of course, you'll be labeled as a shill and, because you're in the industry and not toting the AVS party line, will be fired upon. Get ready.

Originally Posted by cavu

So you are saying that, if I use TOSlink IC (which has no return current), I could use ANY power cord without degrading my audio signal??

Originally Posted by bluesky636

Please. I am only a systems engineer who designs classified intelligence collection systems for an angency of the federal govenment. Please explain to me (to all of us) in easy to understand terms what the heck anything you just said has to do with "imaging."

Originally Posted by Joe Skubinski

Hi John,

You may have covered this but I don't recall... What cable topology are you using when making these measurements?

Originally Posted by rnrn

Seems like a very crude and subjective methodology. How do you decide how many times you repeat the experiment to get a baseline? Did you do blind testing with different cables and different people to make sure there's no bias? How do you choose source material for this?

Originally Posted by rnrn

Seems like a very crude and subjective methodology. How do you decide how many times you repeat the experiment to get a baseline? Did you do blind testing with different cables and different people to make sure there's no bias? How do you choose source material for this?

Originally Posted by jneutron

To what level would you like the explanation? From your description, I cannot glean specifically what you do. Low level RF, low noise analog, server based data aquisition... So I'm not sure where to begin.

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Please ask specific questions, and I will answer them as best as I can..

Cheers, John

Originally Posted by jneutron

The cable topology per se is unimportant to the discussion.

One source, two single ended outputs, one amp, two single ended inputs, two 3 prong line cords, two coaxial IC's. Source output Z zero (for clarity of discussion), amp input z 10K.

When the source pushes say, 1 volt at 20 hz in the right IC, 100 uAmp flows in the IC center conductor. Current always requires a return path, so how does the 100 uAmp get back to the source? By the path of least resistance.

Examine the paths that are available...you have two IC shields as return paths, and the safety grounds via the duplex outlet.

Without the safety ground, the 100 uA will split between the IC grounds, 50 uA in the right, 50 uA in the left. With a massive safety ground, the bulk of the return current will flow through the ground, NOT the IC shield.

As long as return current flows through the safety ground, the actual loop will be picking up any and all time varying magnetic fields. Faraday's law of induction will cause a voltage to be generated around that loop, and that voltage will appear across the 10k input resistance of the amp.

Let's recap the salient point:

The return current does NOT for the most part, flow back to the source via the outer shield of the coax that the signal came in on. For a shield to actually work, ALL the return current MUST flow back on the shield.

For a balanced pair to "shield", in this case by centroid proximity, all the current in one wire MUST return via the other wire.

This is the standard conceptual understanding within the EMC field.

Cheers, John

Originally Posted by Joe Skubinski

This was one of many experiments I created to determine what physical properties within the cable were causing sonic change. Since a scope was of no help and I really could not foresee what any available test equipment could tell me about what I was hearing in this context, I continued to use the only available test gear, my ears.

For example, I made a remote switch to be able to instantly and randomly change between 2 pairs of interconnect, and after using that for a month or so, I determined the results were being skewed by the emotional stress of having to make an instantaneous decision at the time of change. It was a useless method to compare, so shelved that box.

Source material was typically less complicated and clean CD music, at the time mostly female vocals such as Rickie Lee Jones. For me this was the 'sound' I was most familiar with, the sound of my mothers voice seemed to be ingrained in my brian since birth, so I concentrated on trying to recreate what was to me a 'known sonic signature' in playback.

As years went on I experimented with different conductor materials, dielectrics, shield materials, and cable topologies, listening to each configuration for as many months as it took to fully grasp it's 'signature' with the system, while attempting to mentally exclude variables learned from previous tests. In hindsight what was really happening over time was I was training my objective brain (I've always been quite technical) how to subjectively evaluate using my ears.

Originally Posted by bluesky636

What I do specificically has no bearing on your ability to provide a simple, straightforward answer to the question. I will now ask the question (again) as simply and straightforward as I possibly can:

How does a power cable affect imaging?

Originally Posted by Joe Skubinski

In a basic 2 channel system the source and the amplifier, and in video the source and display device, tend to significantly affected in overall performance by our AC cords.

Originally Posted by Joe Skubinski

The reason I had asked was that standard coaxial designs with a braided and/or foil shield never sounded good- no matter what I did they had resolution limitations particularly at higher frequencies, that could not be avoided.

Originally Posted by jneutron

Alas, your area of expertise does indeed determine how best I can explain.

The fact that you repeat a question that was answered speaks clearly on what you understood, and what you did not.

I note with interest that you cut out the explanation of how we image. Does this mean you understand that entirely and consider it a moot point, or are you neglecting it because you do not understand it? Understanding how we image is required to understand what to look for and measure with respect to any changes that can alter imaging.

If my explanation of localization was insufficient, I can elaborate.
If my explanation of loop topology was insufficient, I can elaborate.
If my explanation of Faraday's law of induction was insufficient...you get the gist.
The same applies to the EMC inferences, the pan pot, single ended, sweet spot, return current, etc...

The complexity of the issue requires some basic understanding of every topic I just mentioned. Reduction of the answer to some arbitrarily simplistic description will lose salient content.

As I said, please ask questions.

Cheers, John

Originally Posted by jneutron

Alas, your area of expertise does indeed determine how best I can explain.

The fact that you repeat a question that was answered speaks clearly on what you understood, and what you did not.

I note with interest that you cut out the explanation of how we image. Does this mean you understand that entirely and consider it a moot point, or are you neglecting it because you do not understand it? Understanding how we image is required to understand what to look for and measure with respect to any changes that can alter imaging.

If my explanation of localization was insufficient, I can elaborate.
If my explanation of loop topology was insufficient, I can elaborate.
If my explanation of Faraday's law of induction was insufficient...you get the gist.
The same applies to the EMC inferences, the pan pot, single ended, sweet spot, return current, etc...

The complexity of the issue requires some basic understanding of every topic I just mentioned. Reduction of the answer to some arbitrarily simplistic description will lose salient content.

As I said, please ask questions.

Cheers, John

Originally Posted by rnrn

Could you also explain what correlation measuring the minimum voltage required for imaging using different cables has to listening at normal volumes?

I'm having a hard time understanding what purpose this experiment serves.

Originally Posted by jneutron

You will of course understand my next question: What "proof" do you have to support this assertion of "significantly affected" performance.

...

I am also of the mindset that statements of absolute effect require absolute proof.

Originally Posted by jneutron

When I use the term "single ended system", I am referring to the normal RCA style jack input. The nature of that beast is that it does not control the ground currents when the two chassis are connected to a common safety ground.

To alleviate this, balanced systems are used, and as you mention, optical.

The direct answer is, optical will not suffer ground loop issues, therefore, the variation in ground parametrics such as inductance, resistance, and loop intercept area I speak of can have NO effect on a fiber based system.

If a line cord can affect a fiber based system, my first thought would be that there is a pathalogical problem with the equipment.

Balanced differential systems should be as impervious. However, the methods and geometries used in balanced design can still couple to ground loops, a la pin 1 problems, so caution in design is still warranted.

Cheers, John

Originally Posted by Joe Skubinski

This was an early experiment that came to mind when the discussion began about soundstage image, but the gist of it is that at some volume level of listening our brains ability to localize drops out, just as a digital device gives up once the data loss reaches a threshold.

You could also work toward concluding the opposite in that this low level information is what the brain is accustomed to using to create this mental image. A high volume level of information is not necessary and in fact can be detrimental as the increased gain would also include an increase in noise or other artifacts which the brain also attempts to process.

In other words, the greater the low level detail cues that can be extracted from the source, or the original event, the easier the brains job is in recreating the mental image.

Originally Posted by bluesky636

Alas, my area of expertise is classified and NOYB.

Originally Posted by bluesky636

I have no intention or interest in getting into a line-by-line (What's next? Word-by-word?) back and forth with you as you seem to so enjoy doing.

Originally Posted by bluesky636

Your answer above (or lack of an answer as the case may be.) clearly demonstrates that you are incapable of and/or unwilling to provide an answer to any question without resorting to "technical" mumbo jumbo and jargon designed solely to impress and intimidate (I am neither, by the way) the questioner with your "knowledge".

Originally Posted by bluesky636

IMHO, the mark of a truely knowledgable person is their ability to tailor their responses to their audience's knowledge and skill level.

Originally Posted by bluesky636

On that count, you fail miserably. Goodbye. So long. Sayanara.

Originally Posted by David James

He has asked a question, one which you can't seem to answer. You are great at throwing out words, lots of them, but there at least two of us who are beginning to wonder if you are simply attempting to baffle with ********. Please consider the possibility that it's you that are the weak link in the ability to convey your message.

Originally Posted by Chu Gai

John, would this also apply to devices that can be inserted in between two components where the RCA goes into something like the Ebtech Hum Eliminator?

In a basic 2 channel system the source and the amplifier, and in video the source and display device, tend to significantly affected in overall performance by our AC cords.
Joe Skubinski, JPS LAbs

Originally Posted by jneutron

You will of course understand my next question: What "proof" do you have to support this assertion of "significantly affected" performance.

While I have certainly supported an argument reflecting the system geometry and causal paths involving IC's and power cords, I am also of the mindset that statements of absolute effect require absolute proof.

Cheers, John

Originally Posted by jneutron

I always consider that.

Now what do you not understand?

Cheers, John

Originally Posted by bluesky636

How does a power cable affect imaging?

Originally Posted by David James

Here you go