Re: Violin Plate tuning using Modes

In article <[EMAIL PROTECTED]>, PeteSchug
<[EMAIL PROTECTED]> writes
>You might want to read Al Carruth's articles on the subject in American
>Lutherie 28, 29 and 30. They are available from GAL. (I think I have the
>right issues listed)
>
>The first is a theory article describing modes on flat plates, the second is
>about violins mostly and some on other string instruments, the last is about
>guitars.
>
>Al uses a loudspeaker to drive the plates and cautions about using ear
>protection while doing it. I live in an apartment and anything that needs
>ear protection is out. I have a workshop in my apartment and I really don't
>want to draw too much attention to myself.
>
>I read the articles and I applied the knowledge to tap tones. If you know
>where to hold the plate and where to tap it you can invoke at least three
>different modes. That seems to have been good enough to make a very
>satisfying instrument.

Am I right in thinking that a common problem with cheap violins is
uneven resonance, or general lack of it, in the range from middle C to
the G below?  If so, three modes suitably spread around the lowest air
resonance would be a cure.   

>Nobody really knows if any of this stuff actually works, but a lot of people
>seem to think that the quality goes up even if some violins turn out good
>and the occasional clunker still pops up here and there.

Its advantage over just prescribing thickness is that it takes into
account variations in the density and stiffness of the wood.  We were
hearing earlier from a maker who makes two part plates with careful
attention to the orientation of the annual ring markings.  There was
some indication that aesthetics were an influence, but structural
properties would also be associated with different ring spacing.

>If you want to get techinical there seems to be no limit to how technical
>you can get. Martin Schleske has written in The Strad that he can to
>acoustic copies of violins. His approach is very detailed and technical,
>involving more measurement than building from the looks of it. 

What intrigues me is how you know what to do to move one resonant
frequency without changing all the others in some undesirable fashion.
I can well believe that that is highly technical.

>He is highly
>regarded, unlike the guy who keeps discovering "the secret of Stradivari"
>every couple of years.

-- 
Ken Moore
[EMAIL PROTECTED]
pg composition student, University of Reading