How can power cords make a difference?


I am trying to understand why power cords can make a difference.

It makes sense to me that interconnects and speaker cables make a difference. They are dealing with a complex signal that contains numerous frequencies at various phases and amplitudes. Any change in these parameters should affect the sound.

A power cord is ideally dealing with only a single frequency. If the explanation is RF rejection, then an AC regeneration device like PS Audio’s should make these cords unnecessary. I suppose it could be the capacitance of these cables offering some power factor correction since the transformer is an inductive load.

The purpose of my post is not to start a war between the “I hear what I hear so it must be so” camp and the “you’re crazy and wasting your money,” advocates. I am looking for reasons. I am hoping that someone can offer some valid scientific explanations or point me toward sources of this information. Thanks.
bruce1483
Same here Elizabeth. A realist by nature (some might even say pessimist but I don't think the affliction is quit that advanced) I tried a "designer" cord on a whim. Fully expected to notice no difference. On the source (DAC or transport), where others claim the most benefit, there was no appreciable effect. Putting it on the preamp was another story. The sound was more "musical" and lively. On the amp the difference was VERY noticeable. Here it brought a considerable increase in the heft of the low end and at the same time the overall sound was less strained.

Bought another cord to put on the preamp. Ah, the best of both worlds. Eventually my anal retentive nature caught up and now everything has an upgraded cord. The source didn't really *need* it, but what the heck!

Ultimately it paid off that even as a doubting Thomas I was willing to try something new. If only that attitude could be bottled...
Albert - This isn't personal. I like talking about hifi related things. I don't get upset if someone says that their line cord makes a huge difference. I find it interesting. I don't judge people by whether they use expensive line cords or not. I have friends with whom I disagree about important things. Like you, I am just expressing my opinion. I don't like fighting and I take care not to write anything that sounds personal. I state an opinion and try to back it up with some information. I thought you might find the line cord voltage numbers interesting. It wasn't written with the intent to agravating you or with the expectation that you were going to read it and cry out "MY GOD, how could I have been so wrong!?"... And, I'm sure that if I had a chance to hear your system I would agree that it sounded damn good.
Dear All,
I've certainly read a number of interesting theories on why PCs make a difference. RF/EMI rejection, bigger guage "pipe" to supply electrical power, bandpass filter effects, various sound differences between metal types and purity, mechnical vibrational effects, soldering techniques, noise cancellation techniques and the dielectric content to name a few. Here's a thought. I've read about but never experienced the PS Audio PowerPlants. I've read that changing the output frequency can effect the sound. Sometimes better, sometimes worse. Perhaps the PC is merely removing certain frequencies from the incoming power or modifying the wavelength (or waveform) slightly.
I know that adding Uninteruptable Power Supplies (UPS) to complex laboratory medical equipment makes them run better. Repair costs go down, system failures go down, mechanical irregularities go away and precision improves. D/A and A/D convertors certainly work more consistently. There are power supplies inside the equipment that should protect and clean up the power. I've noted times when the power monitors showed no spikes or brown-outs but the UPS aided equipment ran better. So what's up? Personally, I don't know (I was a chemist not an EE). I can usually hear differences between PCs. Sometimes I like them, sometimes I don't. Hey, enjoy the music. It's not worth fighting over.
I'm going to take a whack at this and would first like to establish my credentials. My experience with the scientific aspect of electronics is limited to the DYNA ST-40 amp I built back in the 70's. When I was done and put the cover on the box, I was struck by the little yellow label that said, "caution, no user serviceable parts inside". Truer for me than, I suspect, for many kit builders.
However, I do know a few things about science and the philosophy of science. One of those is that there is something called "electron theory". No one, not any of us or any Nobel Laureate KNOWS what electrons do or if they even exist as the theory supposes. It is just that, a theory.
I regard audio equipment designers, for that reason, as wizards in the true sense. They manipulate forces beyond their understanding to perform miraculous feats. Stevemj and 70242, on the other hand, are like the 14th generation of high priests who keep the scrolls that they can't read but you'd better not look directly into the eyes of the idol or you'll be struck down.
Way back when, kids rolled paper into a cone, stuck a needle through the narrow end and held the needle to one of dad's 78's while it rotated on the Webcor. Sound ensued. How much difference is there between that and a Goldmund Reference? Only one of degree. One has a suspension based on theory, the cone doesn't. One has amplification of the vibrations based on theory, the cone doesn't. The child with the cone doesn't know why there is sound, but empirically, there is. The modern turntable designer likewise doesn't know, although he'll probably tell you he does. His work is the result of empirical observation and a "belief system" grounded in a theory, not in fact. We laugh at the notion of an 18th century Dutch scientist who believed a little person he called a "homonculous" bent the light through a prism. Everyone knows that Newton "proved" that the light was bent due to the refractive nature of the glass' shape. Yet, we don't know why that particular shape bends the light, only that it does.
Electromagnetic theory "supposes" invisible, "sub-atomic" particles that have cause and effect. We can only observe the gross consequences of the theory. Where a finer understanding is desired, such as what is going on inside a power cord or a transformer, with impossibly tiny amounts of a theoretical concept called "current", we rely once again on empiricism, not objective truth.
Ohm's Law is not a law. It is a mathematical formula that allows "theorists" to predict the behavior of current, which, once again, is part of a theoretical model. Heisenberg's "Uncertainty Principle", while elegant and brilliant, is more of an apology for the inability to observe energy than an attempt to explain it.
When the so-called "objectivists" deride the notion of our tweaks, condescending to admit that perhaps any audible differences stem from something "outside of the LAWS of science, as we know them", that is the worst sort of hypocrisy and a telltale that they have no understanding of the true Science that lies at the foundation of rational thought.They are simply acolytes who guard a temple of their own creation to defend themselves against forces they do not understand.