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.
The fallacy of ac treatment
I see a lot of threads related to managing and tweaking the ac powerout end of electronic systems. Much has been said about dedicated wiring, termination and even the right kind of extension cords to use. I work for an electric utility; and that's the extent of my credibilty here. The majority of you will no doubt be far more erudite wrt music hardware. Just a thought, though: domestic ac distribution goes thus: power station-step up-city-step down-subdivision-final step down. As far as the utility is concerned, you and all your neigbours are collectively the load for the step down tranformer. Any inductance/capacitance created by your neigbour running motors/tubelights, etc is felt by the lot of you. Additionally, the voltage frequency will almost always move around a tolerance from 50hz as the whole country turns on the air, off the lights - changes all the time as peaker plants ramp up etc. Nothing can change that- the frequency of the grid supplying your city is the frequency in the mains at your house. So what's my point? Well only that how much difference can the last 10 feet of cabling, etc make when the other hundreds of miles are outside of your control? And more importantly, frequency is one of the most imp parameters for measuring electricity quality (your expensive hand-coiled toroids are entirely subject to the f in the primaries) and nothing other than running an f generator can shield you from that. Methinks all the improvements you see from ac cord treatments are pyschosomatic. But that's cool.
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- 68 posts total
- 68 posts total