Hi John, > Thanks for your interesting post. I am saving it for future study. > There's likely to be relevant stuff here, especially about how some > compliance could help efficiency. The impedance matching across a > flexing beam (harmonic motion is a factor hear?) is intriguing but this > will take more time to sift down to a conscious layers. No, not harmonic motion. Impedance matching applies in many physical situations. It's basically a way to balance force/distance tradeoffs or voltage/current tradeoffs or so forth. In rather simplistic terms, impedance is a reflection of the amount of force needed to effect some sort of change. In mechanical situations, impedance matching is generally achieved through some sort of mechanism that applies a mechanical advantage. For instance, in the middle ear, a large sound collection area (the eardrum) is used to collect airborn sound from the low impedance side and transfer it (with some degree of leveraging) drive vibrations over a much smaller area on the high impedance fluid side (the inner ear). > Were you some sort of circus engineer before heading into piano (so > called) technology? It looks like the clowns have better R&D than us > piano people. But I always thought this and now I know for sure. LOL! I think Steinway and Sons probably patented a number of P.T. Barnum's innovations. > It's not really the rail that is radiused it's a 1/2 dowel covered in > felt replacing the usual ring-o-felt balance rail punching. The radius > is about 6mm. Gads. Well, that answers my question: It was nothing more than a marketing gimmic. (Big surprise.) The change in mechanical advantage from the key rolling over a 6 mm radius would be miniscule -- really, really miniscule. Yes, it's enough to *technically* claim accelerated action and get a patent. But why bother? What I had envisioned was a very broad radius (dunno... perhaps 25 cm or more) that would shift the fulcrum point more substantially. Of course this would cause the keys to slide vertically on the balance rail pins (slightly). I don't know if that would present a problem. BTW, I had another thought after I fired off my last post. The springboard mechanism used by acrobats also achieves something else. Suppose a heavy acrobat is to propel a light acrobat into the air (much higher than the heavy acrobat's original drop point). There becomes an issue of where to place the fulcrum, if a standard fulcrum is used. If it is placed in the center of the board, for instance, not all of the kinetic energy will be transferred, and the heavy acrobat will hit the ground with a bump (wasted energy). The fulcrum point would need to be off-center in proportion to the weight differential. At that point, there would be an impedance match. However, with the radiused fulcrum, placement is not particularly relevant. At some point in the roll, impedance will be matched. Full transfer of kinetic energy will occur. Carrying this lesson back to the piano, how does one design a piano's action to work equally well for the light fingers/arms of a 6 yr old student and for the heavy fingers/arms of a large-framed man? With a radiused fulcrum. Interesting application. > What's a "Wissner"? My piano -- an obscure make from the early 20th century -- a very nice instrument in need of lots of TLC. Peace, Sarah
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