How does length affect power cable sound quality?


Wanted to bug y'all about a basic power cord question: How does the length of the cord affect sound quality? My gut says that shorter is better, but maybe there is some form a filtering required that makes length a necessity. For me, a standard 6 foot cable is estheticly 3 feet too long (at least--I could use some one and two foot cords).
Does an 8 footer sound better than a 6? is 10 better than 8? How much worse is 3 feet instead of 6?
In short, what is the optimum length, and how does sound quality suffer when that length is shortened or lenghened? Obviously, the exact type of cable used must be considered. Specificly I've ordered a "$200 msrp, $150 retail, cord for $50" for a Virtual Dynamics Power 3 Power cord, currently on AudiogoN, and available at that price for about 30 days, according to Rick.
brtritch
Since some cords use specific geometries to achieve desired impedance characteristics, it is possible that altering length could alter their overall performance. With that in mind, doubling the length of a cord could double the effective capacitance. In a reverse situation, using a cord that was half as long would cut the capacitance by 50%. Same can be said for inductance too. Whether or not this would come into play at all would vary from system to system and location to location.

Another factor that could come into play is susceptability to RFI. A longer cord makes for a better antenna. As such, if you're going to run long cords, make sure that they have adequate shielding or take advantage of geometries that offer "natural" shielding to RFI.

Also make sure that you're using a cable that is heavy enough for the device that it is connected to. Whereas an 18 gauge cord might be fine for a CD player, tuner, etc... it is not suitable for any reasonably sized power amplifier. Sean
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In systems like the power feed or amplifier feeds, the output impedance of the power source is very low. Because of this, the capacitance between the two conductors is not important. The series inductance is important because current transients that surge through the wires will meet with extra resistance due to the inductive reactance. This will create a transient voltage drop over the length of the cable. For instance 117VAC becomes 116ACV momentarily. The length of the cable is proportional to the inductance. Longer cable, more inductance.

In the case of the power cord to a power amplifier, anything that limits the current inrush that would normally recharge the amplifier power-supply capacitor bank after it is momentarily discharged, can cause a voltage droop at the power output transistors. Any significant momentary droop at the output transistors can cause audible distortion. You can think of the capacitor bank as both a filter to eliminate 60 Hz (to create DC) AND a battery of sorts that stores DC power potential to be expended when the power transistors demand it during high-power transients. When high-power is demanded, the capacitor-bank (battery) actually depletes, the voltage at the transistors eventually dropping as a result. To counteract this, the rectified AC power directly recharges the caps every half-cycle when the recitifiers are conducting. If the power-cord is inductive (as most rubber cords are), then this recharging action can be limited. If there is no high-current demand from the music, the caps just get charged initially and then very little additional current is drawn from the AC power cord.
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I use and enjoy 5 meter powercords, have several, and some 4 meter ones too. I also have the same brand 1 meter cords, 2 meter cords.. I DO move them around ,and have swapped longer shorter, fatter, thinner... Sometimes the sound changes a little. Sometimes not. I used to need to use 4 meter pC, and I thought they helped. Now with the same brand in two meter or even one, no change.I am using a power conditioner also. However using larger gauge even on source or preamp may change the sound a bit.

Wow how do you have time to write here with all that power cord experimentation going on?