Negative bearing (long)

[Delwin D Fandrich]

This is a multi-part message in MIME format.

---------------------- multipart/alternative attachment

  ----- Original Message -----=20
  From: Richard Brekne=20
  To: pianotech@ptg.org=20
  Sent: December 03, 2001 12:04 PM
  Subject: Re: Negative bearing (long)


  Been reading and weeding through and find much that is interesting, =
but this comment caught my eye and I must admit is confusing. I wrote =
about modal analysis a year and a half back and you came out and said it =
was basically useless in designing soundboards, since the conditions for =
measurement are different then the conditions for full strung, and if =
done full strung well the deed is already done so to speak... further =
you pointed out then that you meant that there was no reliable way of =
forcasting said changes.  =20

OK. My previous answer was incomplete. But you're taking what I said out =
of context. What I said was, "One of the problems I have with most of =
the testing I have seen on the piano soundboard is that it was done on =
an unloaded board and is, therefore, largely meaningless." This is some =
different than you are implying above. It is my opinion that tests of =
this type are basically meaningless unless they are done on soundboards =
installed in a real world piano, strung and loaded. Remember, we're not =
just trying to figure out the specific characteristics of the soundboard =
alone, but the entire, interactive system. No where do I preclude the =
possibility of obtain useable results from pianos that are strung and at =
pitch.

The reason they are not generally done this way is simple. It's very =
difficult to do. You need full access to the soundboard and the plate is =
in the way on the top while the belly bracing is in the way on the =
bottom. Therefore to conduct a meaningful test something is going to =
have to go. Since it won't be the plate it will have to be the belly =
bracing. Before everyone panics, most pianos won't fly into a million =
pieces if the belly braces are removed. But it will be difficult and =
expensive. Hence, it's not done.



  > Hmmm.. In the section of the Wogram article entitled "Influence of=20
  > string tension" He seems to be saying that the condition of an =
uloaded > soundboard is not a problem. He says that the basic impedance =
curve > and sound radiation curves remain basically the same and that =
only the > lowest resonances are effected and that the effect is =
predictable=20
  > enough to take into consideration.=20
  > Is this outdated ??=20

I don't know if it is outdated or not. I disagreed with Mr Wogram's =
position on this when I first read that article and I still do. My =
experience is different than his. I don't know enough of the details of =
his work to have even the vaguest notion of what all might be different.



  I consider modal analysis of the working soundboard to be a good first =
step.=20
  You know, like, "one small step for man...."=20

  Del

I still believe this. It's not going to be the final word, but it can =
certainly help us along the way.



  Stephen Birkett wrote: >=20
  > I have my opinions about modal analysis (mentioned here once a=20
  > while back)...that, at best, it can tell you that the soundboard is=20
  > working as you already know that it is supposed to work. As a =
practical=20
  > tool for design I have my doubts it will ever give anything, =
primarily=20
  > because it treats the sb unloaded and in isolation from the =
interactions=20
  > with the rest of the piano.

Well, as I said. In my opinion the soundboard must be loaded with real =
world strings. None of the published tests I have seen so far have been =
done this way.

Del


---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/50/9f/a0/99/attachment.htm

---------------------- multipart/alternative attachment--