soundboards improving with age? or what else?

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Don=20
  To: pianotech@ptg.org=20
  Sent: June 08, 2001 1:34 AM
  Subject: Re: soundboards improving with age? or what else?


        Hi Del,
        =20
        You are right that pianos are not violins. However,
        are you suggesting that the top and bottom "plates"
        (i.e. sound board) don't vibrate on a violin acting as
        a transducer--just like a piano sound board is a
        transducer?=20

        Yes, but that's about where the similarities end. As you say, =
the four strings of the violin have a total tension of somewhere around =
80 pounds (about 36 kgf.), on the piano its typically between 35,000 and =
50,000 (about 15,900 to 22,700 kgf.). The downforce from the string =
plane of the piano against the soundboard is between 250 lbs 750 lbs. =
(115 and 340 kgf.) I don't know--have never had the need to figure it =
out--the down force against the bridge of a violin but it's going to be =
some very small fraction of that. That alone separates the two.=20
        =20


        I agree there are many differences--but it is not Oil
        and water as you seem to indicate.

        Well, as you say...they are both wood and they both vibrate. The =
list of their structural and operational differences is some longer.


        =20
        There has been some research done on how violin plates
        vibrate in free air. So far as I know there have been
        none done on pianos. Surely both do vibrate, and both
        are wood. It would seem prudent to at least look at the
        research for similarities.

        Oh, I do whenever I come across them. But I don't really seek =
them out.

        Similar studies have been done with the piano soundboard--many =
of them--but they don't tell us much about how the real-world piano =
works. That is not the normal environment of the piano soundboard. The =
piano soundboard (typically) has its entire parameter glued to a =
relatively solid and massive rim in what amounts to a clamped-edge =
configuration. (The mounting of the violin top is closer to a hinged-end =
configuration)=20

        Piano soundboards have also been studied glued to the rim but =
not loaded with all those awkward strings--the plate and strings get in =
the way of the test equipment, you know. Some time back I read through =
the report of a researcher who did some extensive modal analysis on a =
grand piano soundboard. Tens of thousands of dollars were spent on this =
analysis, but in the end the information, while of much academic =
interest, was of no practical value to the manufacturer who had paid the =
bill. The entire analysis was done using an unloaded soundboard. Things =
just change too much once the strings go on.=20

        And it's not just the loading of the soundboard by the string =
downforce. We also have to consider the interaction between the =
soundboard/bridge and the string plane. There are just a whole lot of =
things going on there and all of them are going on simultaneously. The =
vibrating characteristics of the soundboard panel and assembly change so =
much between its freely suspended condition and its more normal clamped =
and loaded condition as to make all of these studies academically =
interesting but practically useless.=20

        There are also some limited studies that have been done using =
loaded soundboards, all of them using vertical pianos--it's easier to =
get at the soundboard in a vertical. We're finally getting on the right =
track.

        I am sure that the studies done on violin tops are certainly =
interesting and they surely tell the researcher much about how the =
violin top vibrates in free air. But I must wonder just how much that =
reveal about how that same top performs when it is fully assembled, the =
instrument is strung and played. In the case of the piano soundboard =
it's like the difference between oil and water.


        =20
        I do agree whole heartedly that the sound production
        is *different*. A high tension piano vs a low tension
        fiddle. (about 80 lbs total tension on a fiddle btw).=20
        =20
        Yup. they are different.

        Regards,

        Del Stamp powered by www.mailround.com=20

        Click here to join YOPTIN and WIN COOL PRIZES=20
      =20


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