Hva gjør en strømkabel god utenom ledermateriale, tverrsnitt og skjerming?
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Power Cords
Q.) I've never tried changing the power cords and I'm pretty sceptical about it. Could you please try to explain in engineering terms how changing a power cord to a source component (CD player) which has an internally regulated power supply, running in a fully balanced system can change the sonic character of the system?
I could understand if there were circulating ground currents between the individual components in an unbalanced system, but in a balanced system ground currents shouldn't be an issue unless the system had insufficient common mode rejection or wasn't truely balanced in and out. Thanks and regards, Sam F.
A.) Sam, You are on the right track with the ground currents. Most cords and power conditioners choke the line current which is useless because the power supply almost always has a transformer on the input that limits bandwidth quite well. Further slowing of the current input is counter productive. Grounds on the other hand are a real issue. The house ground is well too far away to provide any real ground as related to RF or digital frequencies or sharp transients circulating in the system. The wave length of these frequencies is far to short to find a proper ground path so they find paths to circulate in the system as a whole, bypassing transformers because of their inherent asymmetry. This is a multi path condition that cannot be common modded because it is the interaction of multiple path lengths, like a ground loop, but at much higher frequency. This problem can be so bad in shops and studios where there is a lot of digital equipment, that the equipment actually malfunctions entirely. My chords have a substantial cancellation of trans audio frequencies in the ground plane, they are also effectively longer than the path to house ground and in most cases this essentially stops the components from talking to each other if they each have a cord.
I did substantial testing using microphones and microphone power supplies that are very sensitive to this problem. Replacing the power cords is not a total solution but short of battery isolation it beats most everything I have tried, short of lifting all the grounds, which can have side effects far worse. The amount that a power cord can help varies with prevaling conditions. Very simple, single point ground, tube analogue systems are a far better situation to begin with than a broadbanded solidstate digital system. Hope this helps. - George
mvh
