Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics.

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How about a nope, nope, nope..

Posted by jneutron (A) on April 21, 2004 at 06:49:40

In Reply to: Nope, yep, and nope. posted by Jon Risch on April 20, 2004 at 19:47:28:

JR: Where are Jneutron's infamous mosquitoe's when you need them?

Buzzin away..

I wouldn't worry so much about variations in capacitance with the mechanical movement, but variations in the geometry between the two inner conductors for balanced, or the inner conductors to the outer shield unbalanced...Relative motion will change the loop geometry, specifically, the coupling factor between the system to the earth's .5 gauss field..I'v had this occur on my mike runs, although it was a slightly larger field that was present..the magnetized rebar in the magnet production building concrete floor. The field at the surface of the concrete btw, has to be less than 5 gauss, as that is the safety limit imposed here, and since everywhere here has been measured for stray field, wherever we walk, there is nothing over 5 gauss.

JR: BTW, I find it amusing to see you "discovering" all the various aspects of cables, one by one, as you come to SLOWLY (ever so slowly), realize that there is more to audio cables than just dirt simple LCR.

I'm finding it amusing that you, Jon, have not come to the realization that the dirt simple LCR may in fact, be all there is to cables and the variations in sounds..I elaborate:

Having read the Nordmark paper, which was a reference cited in the Earthworks link you so kindly provided me on Feb 24, 2004...I am researching the following:

Nordmark details the human capability for lateralization of source based on L-R delays..He produced a graph, showing how humans (three test subjects in this case) show the ability for delta time lateralization on the order of 1.5 MICROSECONDS, when bipolar jitter was introduced into the tone content.. Inverted, that represents a system capable of 500 to 600 KILOHERTZ response..

We can all agree that we are incapable of hearing tones in excess of 20 Khz, give or take. But 1.5 microsecond lateralization capability?????

Do you have any idea what it takes to maintain a system temporal accuracy at that speed??? And as a side note, your resistive load (as well as everyone else's) is absolutely incapable of remaining resistive at those frequencies..

Holy mackeral...if that time resolution stands as correct, it becomes a whole new ballgame..

It means that the dirt LCR parameters have to be re-measured accurately up to about a Mhz, and will have a huge effect on lateralization of image (soundstage).

It means DC, with it's frequency dependent number, would have to be accounted for..

It means skin effect comes into play, for current density based resistive increase, as well as for transient temporal fidelity.

It means line cords have to have new standards for geometric construction, to alleviate the loop coupling which will affect the amp input.

It means amplifier internal ground current management has to be re-thought, as the line cord coupling affects it..

It means that the power supply loop geometries, those responsible for coupling to the input circuitry, have to be reconsidered...as all I see out there is shoddy construction practices (actually, very good practices for bandwidths up to say 50 Khz, but useless at half a Mhz.. )"
The power radiated by a short piece of wire of length L, in watts, follows the equation: P=40 * Pi * I² * (L/wavelength)² What this means, is that the internal power supply wires become better radiators at higher frequencies, and the input wires the same..(Kerfoot, et al..HFPC, proceedings, april '87)

As you can see...I've been quite busy since our last argument...:-)

And, as you can see...I have done so using tried and true engineering practices.

Right now, I'm busy building a tack welder for accurate resistor attachment for my new load designs..the inaccuracies inherent in soldering 39 resistors in a tubular structure cannot be allowed if I want to make my power load phase accurate to 5 Mhz. My previous load resistor had 39 parallel wires providing return current, which made it rely on the solder joints for current distribution, and that made it less accurate at higher frequencies.

Bought 18 IRLZ34N's, and am now researching aerogel supercaps..am stuck trying to find the pulse current capability of the 2.5 volt 50 farad units, they don't specify it. I'm looking for 500 amp, 100 millisecond pulses for the welder, and need holdup capability of 20 volts per second. The SOA of the fets means I gotta stay below 10 volts.

Cheers, John

Sorry Tony, I know it's off topic a bit..

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