Postby Lordshelinator » September 27th, 2007, 11:10 am
I think you should read this also:
"This is a post from another board to this same article. Don't believe everything you read. The article above stinks of half build conclusions.
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Well, I am not a car audio guy, but I am an electrical engineer.
If I read it correctly, the article tries to build a case that an audio system should ever need a large bypass capacitor to answer surge demands by the amplifier.
Indeed.
By his same logic, no circuit card should ever need bypass capacitors. I am sure that motherboard manufacturers and the rest of the electronics industry will be glad to hear this. All this time, we have been using bypass capacitors on all of our digital components for naught.
The writer is quite impressed with his own limited knowledge of Ohm's law. Conveniently, he leaves out the effects of Faraday's Law, Coulomb's Law, and Maxwell's Laws. These too define how voltage and current conditions can change within a complete system. The inherent inductances, capacitances, and resistances in system wiring alone are enough to affect conditions at the power input to the amplifier in the millisecond range (which will translate to an effect on sound quality). He cites plots taken at a 40 sample/seond rate. This addresses sound quality all the way up to a whopping 20 Hertz (re: Nyquist's sampling rule). Scope tracings at a more realistic rate of interest to audiophiles (say 50 kHz) should tell a whole 'nother story. He discounts minor deviations in the tracings as an effect of alternator temperature. The devil is in the details - not that you can see much at that blindingly fast sampling rate of 40 Hertz.
Ignore the fact that everything else in the system, including the "primary source" (the alternator) has inherent ESR. Ignore the fact that batteries have an ESR. Ignore the battery's transient response (due to the nature of the chemical reactions that need to occur to supply the current) when a step load increase is applied from a booming bass hit. Ignore the transient response time of the alternator's regulator circuit.
Better yet - ignore the whole article."
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