The fallacy of ac treatment

I challenge the fact that you can hear the difference in power cords. The job of a power chord is to supply the transformer inside your piece of gear with alternate current of sufficient quantity to allow your device to operate properly. Inside your component, the power supply converts the alternating current to direct current. The direct current is then sent to power your circuitry. The power supply is where the filtering of your power occurs. Manufacturers use large capacitors and/or voltage regulators in the power supply to filter any residual AC or noise. The power supply design of your equipment is much more critical than an expensive power cord. The cleaner you make the direct current voltage feeding the audio circuits in your equipment the better your equipment will perform. The only exception to this is if the power cord is not of sufficient gage to supply the current necessary for your piece of gear to operate or if the power cord does not provide a good enough ground path to avoid voltage drops which causes system noise due to ground loops, assuming your AC wall outlet is grounded properly.

You bring up some good points that I did not consider but I am still the skeptic. I whole heartedly agree that the larger the power cable you use, the better off you are! It is safe to say at our relatively low voltages of 110 vac or 220 vac the larger the conductor the less opposition to current flow or resistance (at much higher potentials you deal with the skin effect where current flows on the outside of the conductor only). If we look at Ohm's law, a current flowing through resistance will cause a voltage drop. The amount of voltage dropped is dependant on the electrical resistance (or impedance with alternating current) and the current flow. Any drop of voltage across the power cord is detremental to system performance and frankly dangerous due to heat generated in the power cord itself (remember Power(heat)= V (voltage drop in the cord)x I (the current flowing). The second point I agree with you is on EMI (Electro Magnetic Interference). There are 2 types of EMI we must deal with: Radiated and Induced. The sources of these type of interferences are common to our everyday life from vacuum cleaners to our television sets. Unfortunately the best power cord in the world will not help with induced EMI as the interference is induced on the power source itself. This is the case for a dedicated outlet for yours audio system. There are caveats with this also. If one chooses to use a dedicated outlet the ground at the outlet is the most important consideration. I propose that the ground wire that is enclosed in the piece of romex feeding your outlet may not suffient depending on how far the outlet is from your breaker panel (remember what I mentioned about wire size and resistance). This can be checked by by measureing the neutral to ground voltage under load at your outlet. It should be almost zero volts. If it is not there is a voltage drop and this could be a cause of noise in you system. Radiated EMI is quite another story though. This (in my opinion) has more to do with good design in your component than a very good power cord. Shielding, ground planes on circuit cards etc. have more effect on this than the power cord. The only rule of thumb here is to keep everything as short as possible. If the EMI is higher in frequency, shorter leads make a poor antenna to pick up this. Remember that if the interference is 1 MHz or less a sufficient antenna would have to be over 100 feet long. A power conditioner may help with some of these problems but I submit as an electrical engineer that fancy power cords and power conditioners are not a good substitute for good electrical design and a little thought. Thanks for the reply. Audio sometimes becomes an emotional issue, and it is my pleasure to correspond with someone who is willing to talk about some of the scientific principles behind these issues.

Gentlemen, I do not want to you to think that I think ill of anyone who would purchase that $400 power cord. I merely point these facts out to alert those who are considering the purchase of such an item as to the cause and effect some of the problems for which one may consider purchasing such an item. I merely wish to point out that before you spend your $400 please make sure that that $400 will remedy the problem. Some of the problems I have pointed out, can not not be solved by a power cord at any price. If it makes you happy to spend $400 on a power cord, God bless you. But would'nt it be sad, if one spent the money on the $400 power cord and the new power did nothing to solve the problem because it was a grounding or EMI problem. My point is simply this: try understand what you are trying to remedy and why. It could save alot of time and money and maybe buy you a better designed amplifier.

Redkiwi, thank you for your post. I quite agree that the only true test of whether something has improved your system or not, is your EARS. I have also have done some things with my system that some may consider excessive. I am lucky enough to have the room that I listen in, fairly close to my electric meter and circuit breaker box. I installed a dedicated outlet for my system and ran a pair of #10 wires to my breaker box (hot and neutral only) and a single, very large piece of wire braid directly to the ground rod that sits next to my electric meter. I did not want to depend on the ground system in my house. I float each piece in my system and tie all of the chassis grounds to the ground braid at a single point. I bought some Litz wire on Ebay and made my own power cord to float the equipment. While I really can't say I have improved the quality of sound in my system, I can tell you that I can't hear the ham radio operator next door talking through my system anymore. I was fortunate enough to get my grubby hands on some high quality #6 wire at work and use it between my Audio Research Classic 60 and Theil CS 3.6's, but I did purchase some MIT interconnects to go between my Oracle and preamp (Yeah, I am still a record fan). It all sounds great to me and I am happy :-)