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

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Hi Peter...

130.199.3.22

Posted by jneutron on January 12, 2004 at 11:56:08

In Reply to: Hey, JN, how do you resolve.... posted by Commuteman on January 12, 2004 at 11:09:41:

Happy new year..

Peter: ""the fact that you "proved" the effect is so far down as to be irrelevant, with the fact that you have first-hand experience of a mechanical stimulus on a cable causing an audible effect?""

The writeup was an exercise in figuring out the relative level of a specific effect, in this case, a loud hand clap.(not the finger plucking of Bruce's, but an earlier report of his.) For that hand clapping, the energy generated by the cable in response was 40K times smaller than a mosquito impact..I claim a mosquito impact is inaudible from 10 feet away (prove me wrong).:-)

Now..assume there are 40 thousand people in the room, all within a foot of the cable, clapping their hands...What do you think the spl reading would be for forty thousand people clapping in a 10 by 10 room? I believe Madison Square Garden will hold 19,000 people. Try Yankee Stadium, at 55K seats, with 15K empty..That is a huge spl, everybody knows that...and in a small room???

Now, with that many people clapping...the piezo energy in the coax cable (for this example)will still only be approaching the equivalent of a mosquito splatting...even 80 thousand, or 100, or 500K...how many million people are needed to generate enough signal in a cable to produce enough sound from a speaker that we can hear it in a quiet room? The answer: you can't get there from here..and, suppose my calculations are off by a factor of 10, 100, or even 1000? Get 500 people in a 10 by 10 room, all within inches of a cable....to get a mosquito's worth.

For a mic cable? high gain circuitry...And, the cable was slapping against a concrete floor that has magnetized rebar in it..everyone who has setup mikes for pa has seen this effect, some probably piezo, and some will be from the earth's .5 guass field and wire movement. My work enviro has the rebar magnetized all to heck..

Peter: ""Are you simply suggesting that the specific effect described is not the effect causing the output, or are you suggesting that the output (whatever mechanism caused it to be generated) is below the threshold of relevance?""

For speaker wires, the output is below threshold...for IC's, the one data point available has the numbers very low, but without the benefit of source impedance calculated to get a real source energy. That requires adjusting the load until the signal is 50%..that load represents the source impedance, where voltage numbers can now be meaningful.

Peter: ""You said:
Second, the fact that an effect is real, like piezo, does not necessarily mean that it will be meaningful with respect to wires..""

I mean that piezo is a real entity, and can happen with all plastics. But, that there will be applications where it will be a non-entity, and can easily be tossed out by some thinking and calculations to determine level of effect. Just as "so called motor generator" effects are in fact real, by excersizing some brain cells, one can determine if it is in fact something to be considered as plausible, or tossed into the bad idea heap if it is 4 orders of magnitude too small to be a factor.

I reject the simple "pulling" of real phenomena in explaining what people don't understand...that reeks of free energy, antigravity, and cold fusion.

My knee hurts whenever I hit it with a hammer..the impact MUST be a piezo effect..Or, because the kneecap moves w/r to the bones, and since humans are carbon life forms, the movement of the muscles and ligatures w/r to the earth's magnetic field generates electrical signals which are interpreted as pain..because the electrons are crossing the grain boundaries of the nerve cells, impacting as they go along..Now, my magnetized copper knee medallion (near superconducting, of course) will actually reduce the pain of impact..So buy some now, quantities limited..

Course, a reasonable person would just say...don't hit your knee..and they'd reject the half cocked, total BS explanation just given, because they all have a good understanding that hammer blows inflict pain..unfortunately, the same cannot be said for electronics and cable physics..there will be some that spin some really wild "stuff", and many will simply believe.

As an aside, I spoke with Bruce (e-mailed, actually) discussing his test setup..course, he didn't listen to me...nobody ever listens to me...coupla more years of that, I'm gonna start thinkin...nevermind..

I had wanted him to try the experiment by first using a compass to ding the earth field lines at his table..to show where magnetic north is at the setup...and to run some impacts parallel to the field lines, and some orthogonal...that would rule out a magnetic coupling induced signal if both directions were relatively the same..

Oh well.

It is also possible that impact against a metal will cause the electrons to temporarily fall behind; as the wire accelerates, the electrons don't..

Cheers, John

(sorry for the length of the post.

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The Cable Cooker

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