Intro

A little test was done with two types of coaxial cable that are available to make interconnects from. One has solid Teflon(trade name of a Dupont polymer) and the other has solid Polyethylene insulation between the center conductor and shield. The idea was to look at the piezoelectric effect vs several load resistances. The first was RG400 type(teflon) and the other RG58(polyethylene) type coax.

A section of each coax was looped into a circle of about 6 inches and was flicked with the middle finger. A physicist friend 'guestimated' the striking force to be several hundred Gs, but not more than 500. Because of variation, 4 repetitions of each load resistance were tested. This yielded one very badly bruised nail bed...
This method was used as opposed to others, like dropping an object onto the cable, because I wanted to avoid crushing or deforming the cable. No, this isn't the most scientific method in the world as I didn't have time to locate something that would generate a glancing blow with any consistency. However, this gets the point across when some "authorities" claim that vibration induced from you system is causing horrible distortion products.

The results are on the next page which consist of the output generated by this action as captured by a Tektronics TDS460A digital storage scope. The scope has an ultimate sensitivity of about 500 micro volts peak-to-peak. The number at the right of the graph, next to the delta is the peak-to-peak voltage generated.

Conclusions

The first thing you'll notice is that the voltage swing decreases with decreasing load resistance. You'll also note that there are no results shown for Polyethylene for a 100 ohm load. This is because the voltage generated was too small to measure with this set-up.

The output impedance of most consumer electronics and especially "audiophile" grade audio equipment will be below 1000 ohms, more likely, 50 to 100 ohms. Therefore, your interconnects are not likely to generate any significant energy from the tiny amount of vibration induced(which is probably about the same amount of energy expended by a mosquito doing a push-up) by the acoustic output of your speakers unless you had a hammer connected to your woofer and it was beating on them.

You'll also note that the teflon coax is slightly worse than the polyethylene coax in the total voltage generated. Poly seemed to taper a bit more slowly though and teflon had minor ringing at a lower frequency for longer periods of time.

Before you hyperventilate and try and tell me that many of the scope images show the poly as having a higher output, make sure you double check the vertical sensitivity the measurement was taken at, it isn't always the same!

Okay, onto the pretty pictures