Modal Analysis

[Greg Newell]

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Del,
         I wonder if you might help me understand this. You say, "And a=20
good example of why soundboard cutoff bars can (should) be used to some=20
advantage." In the views I saw on the web page there seemed to be quite a=20
bit of movement in the area normally eliminated by a cutoff bar. If there=20
is that much movement is that not contributing to what we hear rather than=
=20
detracting from it? As I type and look back at the pictures in another=20
window I'm tempted to rationalize that while one part of the board,=20
specifically that part in question, is on the down part of a wave the rest=
=20
of the board is up and visa versa. Is this what you wish to eliminate with=
=20
the cutoff bar so that the board acts as a whole instead of in separate=20
parts? It would be interesting to see what the board would do using this=20
modal analysis with a cutoff bar installed.
         This brings me to another question. In all of the examples I've=20
seen of pictures with cutoff bars installed, all seem to be a great deal=20
smaller in size than the corresponding inner rim section they are=20
replacing. I understand that they are epoxied into the existing inner rim=20
and doweled as well. I further understand, I think, that the cutoff bar is=
=20
attached to any support beams over which it passes. Do the combinations of=
=20
these items make it unnecessary that it be of similar dimension as the=20
inner rim?

Greg



At 03:09 AM 5/9/2003, you wrote:


>----- Original Message -----
>From: "Alan Forsyth" <alanforsyth@fortune4.fsnet.co.uk>
>To: "Pianotech" <pianotech@ptg.org>
>Sent: May 08, 2003 3:27 PM
>Subject: Modal Analysis
>
>
> > >Del,
> >          Can this type of modal experiment be reproduced? and if so,=
 how?
> > Greg Newell>
> >
> > Hi guys
> > Thought you might like to visit this website which explains modal
>analysis.
> > I found it quite interesting.
> >
> > http://www.speech.kth.se/music/5_lectures/wogram/modal.html
> > Regards
> > Alan Forsyth
> >
>
>And a good example of why soundboard cutoff bars can (should) be used to
>some advantage. Especially with a board as large as the Bosendorfer.
>
>Now It would interesting to see what the vibration modes would be like with
>the piano strung.
>
>Del
>
>_______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives

Greg Newell
Greg's piano Fort=E9
mailto:gnewell@ameritech.net=20

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