Well, I read it to the point where he got on to power connectors.
What he is initially doing is using a square wave to illustrate differences between pieces of cable, well that's no revelation in itself.There will naturally be detectable differences with such an arduous test. This is hardly a proper investigation of differences between power cables that work at Mains frequencies.
The time base is set at 5 uS/division or 1/200,000 of a second/division that is equivalent to measuring differences at 20,000 c/s not at 50 or 60 c/s.
If you measure cables with different resistance then naturally you'll get different results in current flow and voltage drop.
He does not care to mention whether both cables are of the same length, they are obviously of different resistance values and different gauge.
The point here is that this test highlights nothing at all. Such transient differences over such a short time of a 1/20,000th of a second on a 1/20th of a second timebase ( 50c/s Mains) is ridiculous, particularly when this would only happen when you initially turned on the amplifier when the storage capacitors charge.Once that happens there is no
great influx of current into the power supply thereafter, there is only some topping up as needed.
So an ordinary power cord supplied by the manufacturer is more than adequate for the purpose.To QuoteCG: Right. Remember this is a transient burst of current because power supplies pull current in pulses. They are not like fans or lights, where power is drawn continuously across the full waveform of a power cycle.
Power supplies pull current in pulses. If you don’t understand that, I’ll show you very simply when we sit down basically how a power supply works. But for now, let's look and see how this standard power cord reacts to pulsed current delivery.
I don't see anything different between the two power cords ( their respective curves) except the effect of D.C resistance marginally limiting the initial current surge that would flow into the storage capacitors......and that is a good thing. Remember the power transformer that would be connected to the power cord will have substantially higher winding resistance than the very worst power cord one could buy. So this test is completely irrelevant as any difference in power cord conductivity is annulled, that is, once the primary winding of the transformer transfers electrical energy into the secondary winding and then rectified the storage capacitors are then charged, any differences between the two power cords is negated.
But now he considers 'pulsed current delivery'
and its influence on the power cord in use.
So once the amplifier has been turned on and the initial charging of the storage capacitors has taken place any initial charging current transient has passed. The capacitors will be charged to almost the peak voltage of the secondary winding ( i.e minus the bridge diode loss when current flows), there is very little 'ripple' on the HT + and - rails of the amplifier when no signal is being amplified. Of course, once a reasonable output signal is developed across a connected load (loudspeaker) a 100c/s rectification 'ripple' does appear on the + and - rails due to the current demands on the power supply.
Now with the storage capacitors fully charged to the peak secondary winding voltage, the bridge rectifiers become reversed biased so there is no conduction at all through them,there is also no 'ripple', but once the amplifier begins to produce output current through the load 'ripple' again appears on the bus rails and the rectifiers begin to conduct again in accord with the difference in voltage between the secondary winding and the storage capacitors.
But this 'ripple', regardless of its voltage value, only has a rise time equal to a 50c/s Mains frequency (it is not a square wave) thus any 'effects' made on the primary winding side of the transformer by the connected power cord will only be that due to 50c/s Mains current,not by any other cause.These 'pulses' he refers to is the 100 hertz 'ripple' and are not real transients but pulses with very slow rise times, much like sloping hills, and do not impose undue demands on the transformer or its power connection to the Mains.
For instance, one needs a 300VA power transformer to deliver 200w RMS via circuitry to a load, so the transformer will only draw 1.25 Amps from the 240 v Mains to provide that output, but could easily draw 30 to 40 A at the initial charging of very large storage capacitors in an amplifier. This would only be for about 5-20 milliseconds, depending on the time-constant involved, thus if fuses were resistive they would vaporize instantly and would hardly make a marketable product.
But if you want to spend your money on expensive power cables that really offer no benefit at all but are only a fanciful means of connection then by all means, but that's all you get for your money.Sorry about the techno waffle but as this article's claims are founded on techno baffle, it needs such a reponse no matter how badly put together by me.C.M
Edited by Chicken Man, 18 January 2012 - 10:05 AM.