Why Expensive power Cables when Romex behind Wall?

"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."

Sorry, but this is technically nonsense. Ask an engineer friend whether this makes any sense. You are mixing shielding from EM fields and mechanical resonances. Shielding eliminates susceptability to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance.

"It may be a long wait before technology is developed that "proves" how some power cords work in our systems. Having heard significant improvements with several power cables, I don't intend to wait for a piece of paper telling me what I already know is true."

What is wrong with the analysis I just did above? It proves conclusively that lower inductance power cables reduce impedance to current flow by 22% or more in a typical home scenerio. Do you not understand the analysis?

"I intend to purchase a couple of plates next time I visit Home Depot. Worse case I return them a few weeks later."

I cannot believe that you guys are inventing your own "snake-oil". Best of luck.

I have tried my best to actually do the science to prove which effects are significant with all types of cables. This is significantly more than 99% of the cable manufacturers do. I even publish the experiments and the results. Evidently the public is hard-pressed to read this and understand the significance.

Audioengr - One thing I have learned in Audio is that measurements aren't necessarily worth the paper they're printed on. What measures good usually - in most cases -doesn't sound good. Measurements don't tell the whole story.

I trust my ears and not fancy-schmancy SPICE simulations.

Here is an Audioengr blooper:

Audioengr wrote:Shielding eliminates susceptability to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance.

Duh! Anytime you increase the mass of an object you potentially change the frequencies at which the object resonantes. Adding shielding to a cable will change the mechanical resonance of everything it touches.

Read a thread in Audiogon's Tech Talk Forum Entitled:Tweaks & How My System Disappeared by Jadem6 - a well respected Audiogon member who has been very diligent in tweaking his system.

Most of the changes he's made have been in regard to the Mechanical Resonance of his system. But I am sure that's placebo too right?

Regarding Audioengr's comments on Audiogon vs. what is stated on his website as it pertains to his discounting of the effects of Mechanical Resonance in this thread, Audioengr wrote:

No contradiction. If you take the time to read the paper, you will see that I am talking about ELECTRICAL resonance, not mechanical resonance.

Hmmm.. well given that the second sentence in your "FAQ on resonance" reads:

Resonance can be excited by many phenomena. If you pluck a guitar string or strike a bell, they will ring at their natural resonant frequency and then decay over time due to losses in the systems.

This doesn't imply that you are speaking of electrical resonance. Unless you have an electric bell. So I read further.

ANYHOW get this!! I cut and pasted the text from his Resonance FAQ into a text editor, did a search and find on the text - and bingo! It doesn't even have the word *Electrical* contained in that FAQ. It doesn't say electric, electronic, or even electricity. Whatever Audioengr! What are you hiding?

Audioengr wrote:
As for your metal outlet covers, I beleive that you are experiencing the placebo effect. There is no scientific explanation as to why this should make any difference whatsoever. Resonance requires a high-Q system, which this is not. Even if the outlet cover resonated, what electrical effect could this possibly have?

Guess it depends on what science you subscribe to.
So get this, DUDE!!! there is no electrical effect. This is what I keep saying to you.

When you plug in your power cord and it snugly presses against the metal outlet cover, the mechanical properties of your power cord (and system) change. Maybe you will understand this:

plastic plate + powercord + system = X
metal plate + powercord + system = Y

X sounds different than Y

Nice math huh?

When power flows through the power cord pressed against a plastic cover plate they resonate together. When power flows through the power cord with a metal cover - they resonate together (but differently). The cover plate has an effect on the power-cord and hence the rest of the system.

Plastic is a bit dull sounding and metal is a bright sounding. The thicker the metal the less bright.. wood is odd sounding and not what *I* hoped it would be... the best is to just remove the plate all together.

Audioengr, since you singled out the following quote that I gave credit as POSSIBLY being part of the explanation of why cables sound different.

"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."

YOUR RESPONSE WAS:
Sorry, but this is technically nonsense. Ask an engineer friend whether this makes any sense. You are mixing shielding from EM fields and mechanical resonances. Shielding eliminates susceptibility to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance.

MY EXPERIENCE IS:
I have Soundlab Ultimate One speakers, and the brands of AC cables connected to them and to my ( home theatre use only ) sub woofers make a huge difference in sound. Crazier still, disconnect the sub woofers from the wall and the performance of the Soundlab is improved.

The amplifier and resulting magnetic field of the sub woofer ARE interacting with my Soundlab. This may also be proven by placing a large shield between the sub woofer and the power supply of the Soundlab. I had Purist Audio build such a shield and among a group of six listeners the change of inserting and removing was obvious to every member, every time.

I still contend that there are many things going on in an audio system all at the same time. Any number of changes in equipment and cables can effect RF, magnetic and electrical interference. I've tested TI shield, Purist's shields, Audio Prisms wall filters, dozens of audio grade power cables and ferrite blocks purchased from Ferishield in New York.

Bottom line is they all change the sound. Some can reduce one problem while messing up something else. Ferrite for instance, is not to my liking even though it can reduce or eliminate some radio signals.

As for the wall plate that Bwhite is discussing, I never said that it was effective, only that I am open minded enough to experiment.

I don't know if you are familiar with Marigo dots. They are varying size stick on dots that are manufactured from lead and other materials.

Placing a single dot the size of a pencil eraser on the end of an electrical plug DOES change the sound. The dots work on interconnect cables, equipment faceplates and even on amps beside the speaker posts.

Since these cannot possible have any electrical properties, they are effecting the mechanical properties of the component, regardless if electrical or mechanical in nature.

Seems logical then that electrical plates could contribute to the systems performance.

Anyway, the cost of such a test is miniscule. I have many failed experiments in attempt to improve my music system, but I have also found a number of things that helped.

I think it's important to keep an open mind and experiment with a eye toward learning. Closed minds seldom learn anything new.

In my own experiments, the introduction of 2 feet of stranded 16/3 extention cord onto the end of my preamp, turntable or power amp was enough to influence the sound negatively. Keep in mind, the typical 18 awg cord supplied on equipment, has a up to 7 amp capacity. Resistance played no part in the additional 2 feet. If your speakers have at least the resolving power of an LS3/5A, anyone with an open mind should be able to hear the effects.
A simple tool called an Elfix, can eaisily demonstrate the incredible amount of stray currents surrounding A/C wire.
Shielding almost always results in degredation. The ultimate dielectric is AIR, followed by glass. Since these are all near impossible to achieve in a wire, we are stuck with compromises like teflon.
As usual, everything Albert states is true. I tend to agree with BWhite as well. My guess is the wallplates will most definitely hurt the sound if they are metal.......Frank