Sheilded/Unsheilded Power Cords

No technical reason to shield power cords or speaker cables. These are low-impedance output drivers, so crosstalk is not really a concern. The only advantage might be if you wnat to run power cords side-by-side with unshielded interconnects. Then the power cord may crosstalk to the interconnects. This is fairly easy to avoid with minimal spacing however. Shielding just adds unwanted capacitance.

Marty9876 wrote:

The field an unshielded pc gives off seems to be large, at least 12 inches.

The fields may be large depending on the construction of the power cord. Many cord designs are field-cancelling, and they are not shielded. I dont doubt the you measured larger fields with unshielded power cords, but what about the ROMEX in the wall? Did you shield that too? This ROMEX is usually substantially longer than the power cord.

Also, did you have more noise with the unshielded power cord than the shielded one?

The reason that I ask is because I have seen many audiophiles chase their tails trying to eliminate noise with shielding on IC's, power cords and even speaker cables when the problem turned-out to be a ground loop. Since your system is all single-ended, this is more likely. Using more than one circuit outlet to plug all of the components also increases the likelyhood of a ground-loop. Grounding and shielding is a non-trivial field of science. I have taken courses from industry "experts" in this field.

On the flip side the "dynamics" seemed improved with the shielded DIY's. The highs seem higher and the lows seem fuller. Interesting...

This may be true, but it is difficult to attribute this to the shielding. The new cables were likely lower capacitance or lower inductance as well.

Please explain what "unwanted capacitance" means. Is this the ability of the wire to store a charge?

Yes, but it also contributes to a low-pass filtering effect when installed in the system. Creates an impedance to high-frequency currents.

I hope I am not describing a long winded minor ground loop hum. This was not the purpose of the thread. This background noise is very minor.

It seems to quack and look like a duck....

Sean - No offense taken.

Why is it that most engineers / designers / manufacturers have such a hard time thinking of a power cord as being anything more than a "conduit for power delivery"

I can only speak for myself. A power cord is just one segment of a longer power transmission circuit, which can be described as series resistance and inductance and parallel capacitance. However, the catch is whether this is described as a lumped parasitic or a distributed set of parasitics, like a transmission-line. The former is used at low frequency and the latter at high-frequency. The debate goes on ...

Aren't the internals of a PLC made up of capacitors, inductors (which is nothing more than wire or wire on a former), resistors, diodes, impedance altering devices, etc.. ??? What would stop someone from applying filter technology and the associated componentry to a power cord design ?

Nothing. You can get filtering effects from different power cord constructions or just add filtering elements to the cord, such as inductors, ferrites, resistors and caps.. I do not happen to believe in filtering in PC's myself, except for the ground wire. This can be useful to minimize noise from ground-loops.

Stop thinking of a power cord as an extension cord and start thinking of it as a part of the power supply.

I agree. Certainly is a part of the power system. As is the transformer on the pole and the transmission lines that deliver to that. However, the further that you get from the component, the effects of the component load on the system become smaller and smaller because the impedance of the source gets increasingly lower. At some point, you ignore the effects because they are second-order. I have chosen this point to the be power panel in the house. This causes a small error in any calculations of power delivery.

Bwhite wrote:

I dare you to find a Power cord that measures well and lets put it up against an Elrod Signature cord, Electraglide FatMan K, or Shunyata Anaconda Vx. I'm sure all three of these cords measure differently and all worse than an "ideal" cord... yet, I guarantee they will absolutely blow the doors off anything which measures good.

Be careful what you ask for, you might get it. I have a very good cord, the Magnum2, which measures and sounds good (reviewed in BFS issue #140). However, my new reference cord, the "Grand Slam" will measure and sound even better. I believe it's going to be the one to beat.

If other manufacturers would publish measurements on their cords, at least a comparison could be made. However, it seems that none of them do. I don't believe there is another manufacturer that has a plausible theory of why one power cord sounds better than another. At least I have this.

Then.... YOU can publish the measurements on your website. Hey! That's a great idea!!! Then there would be no mystery, no pouting and wishing that other cable manufacturers published their own measurements.

I wish it were that easy. Besides the possible legal issues with naming other manufacturers on my website, there are actually laws in other caountries against this. Best not to do it.

If making a cable sound good was as SIMPLE as making it measure good, every single manufacturer out there would be publishing their measurements and people would buy the cable that measured best. It would be a simple world.

True. However, even if I prove that inductance or some other parameter accounts for most of the performance of a cord, there will always be second-order effects that are less audible that can be optimized with good recipes, such as dielectric absorption, magnetic distortion etc..... These are much more difficult to measure and there are no standards for measuring these either.

Sean - do you want to be in the cable business??

Here are the requirements:
1) be independently wealthy, because you will not make any money
2) be neurotic about audio and audio components
3) some engineering background
4) really good ears....