Sheilded/Unsheilded Power Cords

I agree with audioengr, shielded power cords are unnecessary. The extra ground capacitance and dielectric distortion is undesirable.

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.

Honestly, when I was done braiding the wire and all the mess, the DIY were going to be better...No matter what :).

I had not a/b the cables, until just before this reply. "more noise" between the two- nope. Seems to be the same. I had meant this for another post, how much noise is too much? The old crank the volume and stick your ear up to the tweeter, I do here a little noise. Not heard from the listing position, but can hear with my ear on the tweeter. Not sure really how to put this into words. The tuner will bleed into the next/nearest analog input. $6000 bucks for bleeding inputs, huh.

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

The amp circuit to the wall is unshielded, all runs in the room are shielded. The source circuit is actually shielded all the way to the breaker panel. I use balanced ic where possible, from the processor to the amp. With HT, one seems to have a few more devices, which seem to add more possible problems.

No, the existing ROMEX are not shielded. That's the reason a normal person would buy the live lead finder pen(I gotta find out this thing is really called), to find these lines. My equipment is also not placed directly up against a wall, next to these lines.

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

Also the power conditioners in the system are a ps ultimate outlet ran into a Richard Gray 400. Really weird part with out the power conditioners, the buzz is 75% louder, plain as day. What I would call very bad. With the ps, same. With the "noisy" RGPS, very quiet. Funny, exactly the opposite of what I would have thought.

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.

Learning something new every day,

Thanks all
Marty

Audioengr: Sorry to step on your toes, but thanks for proving my point. Your line of questioning to Marty just goes to show that even those that i consider to be "worthy" and design / manufacture PC's think of them as nothing more than "an extension cord" ( hypothetically speaking ).

While you have a point about what happens upstream from the PC, you also have to take into account several other factors:

1) One can piss anywhere along the river that they want. So long as the contents of the river are highly filtered prior to delivery to the water fountain, i don't care what takes place. In effect, one could use unshielded wire for a few million miles. This would in no way reduce the effectiveness of a well designed filter at the end of the wire.

2) 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" ? 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 ?

3) The fields generated by the in-wall wiring are not anywhere near as close to the low level signal carrying cables and components as the power cords are. Therefore, EMI and radiation from the in-wall wiring is far less critical.

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

Sonic Genius: Your comments apply only to designs that are made by those "thinking within the box". If you were to step outside of the "box", you might begin to see how those factors could be reduced or even put to use as a positive aspect of the design. Certain design attributes are only "negative" when you can't control them or they are not taken into account for. When it comes to AC, signal manipulation is the name of the game. Sean
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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....