A little history..Over at AR, a guy named FLZapped did some piezo studies with coaxial cable. For whatever reason (insanity, maybe?), he started blipping a cable connected to a scope with his finger to see if speaker cables were actually gonna be affecting the sound as a result of piezo-effect on speaker wires.
He has since posted the address of his website, with the results of all his finger banging. I don't know offhand that address.
At Jon R's request, (in a thread further down here), I am providing here the "infamous" piezo post. Since AR has changed formats, I cannot find the whole article by searching in the new one..but, when I plugged in the http thingy that is at the bottom of my printed copy...voila..
Here is the post, for those who cannot get there from here...
>> Discussions >> Cables & Interconnects >> Archive
Piezo wire sensitivity..
jneutron - 07:06am May 14, 2003
In a thread further down, noted as a wire effect was the piezo effect, where a voltage is induced by insulation as a result of impact..
Hmmm..Lets assign some numbers...
FLZ reported using a teflon coax wire, into a scope, 10 meg input impedance..And a loud clap next to it generated a coupla hundred microvolts...
Note:(notation here will be: 200e-6 means 200 times ten to the minus 6)
OK...what's the energy generated?? 200 uV, 10 megohm, power=V^2/R, (200e-6)squared/10e7... 4e-8 over 10e7,,,4e-13...hmmm..pico is 10e-12, so power is .4 picowatts...If we assume duration is 100 milliseconds, absolute square wave, that would be .04 picojoules..
How big is that?? I knew you'd ask that..
RHIC gold on gold collisions at 200 GeV (billion electron volts, 99.995% of speed of light) produce the same energy as two mosquitos hitting each other (why one of the scientists calculated that is beyond me). 1 eV=1.602e-19 joules,,200 billion times that (2e+11 times) makes it 3.2e-8, 32 nanojoules..
So, one mosquito has 16 nanojoules energy at impact.
Ok now,, 16 nanojoules=1600 picojoules...1600/.04= 40,000.
So, a mosquito impact has 40,000 times more energy than the wire pickup energy measured by Bruce..
A typical speaker has about 1% conversion effieiency,,so that means a mosquito impact would be about 4 million times louder than the wire pickup. (Of course, I assume that is a mosquito flying at full speed), and I cannot be responsible for calculation errors based on mosquito size..
Now, IC calc..Assume 10K, 1 volt reference...
1 Khz, half cycle, .5 mS.... 1/10K = 1e-4...times .5mS, (5e-4), energy of one half cycle 1Khz....5e-8..50 microjoules..Piezo....04 picojoules..
50uJoules=50K nanojoules = 50 meg picojoules=5e7 picojoules
5e7/.04= 125e7...meaning, a 1 volt 1 khz half pulse is 1,250 million times higher than Bruce's piezo power..
Ok, Yah, I know, that's not fair, half pulse is only .5 mS...so lets go 100 ms...same duration would be only fair, don't ya think??? That's 200 times longer, or only 6.25 million times bigger than the piezo..NOW we're getting significant here!!! :-0
The lesson here?? First, make sure there are no mosquito's in your listening area...Second, the fact that an effect is real, like piezo, does not necessarily mean that it will be meaningful with respect to wires..
In the end, science will prevail!!!
Cheers, John
----end of copied post-----Unlike the other thread, where technical discussion is being avoided...maybe here there can be some???
One can only hope..
Cheers, John
