Ok. But there is a drum component to piano tone generation. The initial attack sound is, by the nature of how we describe it, percussive and sets the board in motion from where it continues to be driven by the vibrating string. But that attack has its own drum like quality separate from the sound produced by the driving string. Thus the difference between plucked and struck tone. Doesn't it make sense that the quality of the percussive attack is influenced by the location of the bridge in proximity to the rim not to mention the size and structure of the soundboard itself? David Love www.davidlovepianos.com (sent from bb) -----Original Message----- From: "Delwin D Fandrich" <del at fandrichpiano.com> Sender: pianotech-bounces at ptg.org Date: Wed, 23 May 2012 12:25:25 To: <pianotech at ptg.org> Reply-To: pianotech at ptg.org Subject: Re: [pianotech] David Love--Centering the bridge--was S&S something er other I don't know that anyone has done any definitive work on this. I've played around with generating some Chladni patterns on soundboards driven by various types of signals but I don't have anything definitive to report. My general observations seem to indicate that center-loaded soundboard systems-assuming the stiffness of the system is high enough-show fewer strong resonances. We put in cut-off bars to eliminate the corner of the soundboard where a strong resonant node develops that is out of phase with the motion of the bridge. I'll repeat what I say every time comparisons are made between the piano soundboard and some other musical instrument: piano soundboards are not drums. The drum head is a freely vibrating system; it is expected to produce some kind of vibratory motion in response to being struck. The exact nature of the sound produced by the drum is strongly dependent on just where the drum stick or mallet contacts the diaphragm. It-just like the piano string-is struck off-center deliberately to excite certain specific resonances. And, also like the piano string, once the drum head is struck the whole idea is to have it continue to freely vibrate. The piano soundboard is a driven plate. We want it to respond is a predictable way to the energy driving it; we don't really want it breaking up into free resonant oscillations. So far every indicator I have indicates these are easier to control if the driving energy source is located near the center of the soundboard assembly. ddf Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 - Cell 360.388.6525 <mailto:del at fandrichpiano.com> del at fandrichpiano.com - <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of David Love Sent: Wednesday, May 23, 2012 7:33 AM To: pianotech at ptg.org Subject: Re: [pianotech] David Love--Centering the bridge--was S&S something er other I'm thinking more about where over a membrane that the energy is input from. Timpanists or drummers don't tend to strike their instrument exactly in the middle but more off center. They do that for tonal reasons. Center loaded ribs need to be larger to support the same load than non center loaded ribs. The treble section of the Overs piano doesn't have the bridge centered in that part of the piano. Would it sound even better if you could center it? The impedance characteristics of a diaphragm are different if you strike it dead center than if you strike it off center? Why would center be better? David Love www.davidlovepianos.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120523/1c384c34/attachment-0001.htm>
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