Re: Violin Plate tuning using Modes

In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] says...
> We know that there are several good makers who analyse every step of their
> work and every good (and probably outstandingly bad) violins that come
> through their shops, but what we will never know is how good these people
> would be if they skipped all the high tech aspects and just made fiddles.
> 
> We also don't know how much of the high tech approach is used by some very
> good violin makers who don't write about their approach to doing the work.
> 
> In other words, there is no control by which we can say: This is the way to
> go. It is just interesting. The most solid thing you can say is that Martin
> Schleske made the claim that he can make acoustic copies, which is to say,
> violins that _sound_ like the intended model.
> 
> This all stems from the work of Carleen Hutchins, and her article in The
> Scientific American something like 35 years ago is what first got me
> interested in playing and eventually making violins. It took a while to
> realize that not everyone subscribes to that approach, and some of the
> non-subscribers seem to be able to make very good violins.
> 
> The whole thing is as much art as science and it seems like the careful and
> intellegent worker is the one who reaps the most rewards regardless of the
> method.
> 
> A good look at the plate thicknesses of something like del Gesu's Cannone
> might even convince someone that there are some mysteries too deep to
> penetrate.
> 
> Pete
> 
        "snip"

        In the period when I was taking classes in Mrs Hutchins workshop 
(early 1970's) the Catgut Acoustical Society had already published 
extensively on eigenmode tuning of plates, 
 
     http://www.catgutacoustical.org/      

and she used measuremnts of them to guide her work.  She once said to 
our class '(paraphrase) the more I learn about the eigenmodes the less I 
understand them.'  She felt they meant *something* of value, but always 
emphasized sound traditional craftsmanship and the role of intuition and 
listening in producing good instruments. She was meticulus about 
consistancy and accuracy of measurement but encouraged broad discussion 
of theory and meathods.  
        Of the two fiddles I made there, the first was entirely by 
intuition and reading about traditional methods.  It was junk.  The 
second, made with eigenmode tuning was much better, but still a 
beginners effort.  I found it helpful and should I resume the long 
shelved project of #3 I would use it again, because I found eigenmode 
activity of the plates as they were thinned much more informative than 
tap tones (which I also used) and because thickness mapping of gradation 
that may be useful from studying historical instruments doesn't 
translate well from one peice of wood to another.   When all nine 
eigenmodes are active you do know that there is full activity in the 
plate.  You still don't know WX the modes are optimally tuned...we may 
discuss this for another century...but at least we're not trying to 
vibrate manhole covers. 
        An aspect of the CAS work in Mrs Hutchins shop that no one on this 
newsgroup seems to be aware of or discuss were the spectrum analysis of 
instruments.  Members of CAS had identical spectrum analysers in Mrs 
Hutchins, U Michigan and U Cal Berkeley labs which measured the output 
of instruments from a controlled sweep input (90 to 15Khz) to the bridge 
by a calibrated electro-mechanical transducer.  The output to a strip 
chart record about eitht feet long was high enough resolution to "see" 
pitch variations that most reasonable musicians would perceive as "in" 
or "out" of tune.  Thousands of records were made of both modern and 
some priceless historical instruments in an attempt to charactorize the 
spectral responce of "great fiddles" and "trash fiddles."  This attmept 
although muddled by human judgement calls and variability went a long 
way to undertanding of the roles of rib and neck activity, which 
previously had not been considered a factor.  I found quite interesting 
that many of the instruments documented had *BOTH* documentation of 
eigenmode responce and spectral output of the finished instruments as 
well as expert professional subjective human judgement.  Only the 
massive volume of the publication prevented me from following this line 
of inquiry.   We also just "studied wood."