Climate change "science," that's a good one. Good luck isolating the real science from the political agendas.
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Rnm4, What I meant was that it is essentially beyond debate that power cords DO make a difference in the sound of an audio system, not that there is unanimity on WHY they make a difference. And I have no economic or vanity motive in saying that PC's make an audible difference. Just answering the question that begna this thread. So peace, bro (or sis). Neal |
Please do Ralph! Alright... With power cords its all about voltage drop across the cord. Some of that is at 60Hz, and some of that is much much higher- well above 30KHz-100KHz depending on the power supply in the unit with which it is being used. I've seen a 2 1/2 volt drop rob an amplifier of about 30% of its output power. The cord was rated for 10 amps, and the draw was about 6 amps. This measurement was done with a simple 3 1/2 digit Digital Voltmeter. The more insidious problem is high frequency bandwidth. The power supplies of most amplifiers have a power transformer, a set of rectifiers, and a set of filter capacitors. The rectifiers only conduct when the power transformer output is higher than that of the filter caps. So: When the caps are fully charged the amp is able to play. As it does so, the caps are discharged until the AC line voltage waveform gets high enough again that the rectifiers in the power supply are able to conduct. Depending on the state of charge of the filter capacitors, this might only be for a few microseconds or it might be a few milliseconds. Either way, the charge is a spike which has very steep sides- and requires some bandwidth to make it happen. If the power cord has poor high frequency response, it will current limit on these spikes. This can result is subtle modulations in the power supply or even a sagging power supply voltage. Romex wiring found in many buildings actually works quite well. So it really becomes all about that last few feet and also how well the power cord is terminated- molded cords generally are not terminated very well. If the ends of your power cord get warm after a while, you know you have a problem! This can be measured, its quantifiable and also audible as many audiophiles know. Anyone who tells you differently probably has not bothered to do any measurements- please refer them to this post. I can go into more depth but this is it in a nutshell. Incidentally, Shunyata Research is refining an instrument that does a more in-depth analysis of what this is all about. At the link you will see that their tests essentially confirm what I have said here. http://www.theaudiobeat.com/visits/shunyata_visit_interview.htm |
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