Soundpost Material and Seasonal Changes

[MaestronetLurker]

ML, Bruce Carlson has already collected a lot of data like this on the Cannone, and I think it's been published. Maybe you could contact him to find out how to access it.

 

I was aware that he had done some investigating into this with the Cannone, but didn't realize it was so comprehensive (at least judging by the paper's abstract).  I did find the succinctly named

"Measurement and Modelling of Mass and Dimensional Variations of Historic Violins Subjected to Thermo-Hygrometric Variations: The Case Study of the Guarneri 'del Gesu' Violin (1743 Known as the 'Cannone'"

 

I don't see where I can read the full paper.  I'll look again later, but if anyone has a link that doesn't require a researchgate membership I'd appreciate it.  Thanks.

[Anders Buen]

I have seen an experimental instrument used for educational purposes with a screw driven soundpost. It is a while ago I saw this. It was on a musical acoustics course in Udine Italy in 2008 ish (at CISM). And one of the teachers was Prof Bernhard Richardson. He had this violin. With a thin metal ring in the back plate, a hole and then the SP to go through with a fastening screw in it. The mass of the screw and the ring is probably not much important. Such a design could be used to experiment with the tension of the SP in a given position and could as well be used for seasonal changes. However, the SP can't be moved. 

 

I think this problem is solveable, if we want. Other wood types might need a thicker post, so the f-holes might need to be customized. 

 

Changes in MC in wood has an interesting property. It changes all modes at once about the same in % (A Hypothesis). This is probably not so well known. But the effect is probaly that the changes becomes more audible than changes to single or just a few modes (if that is possible to do). I also think the effect of 10% change in MC is larger acoustically than what one gets from changing the graduations say 10% or the archings 10%. I do not think that this has been studied, or at least not published in detail yet.

 

We will have to question all the CT scan and acoustic test data works for instance. The data we get from an instrument is highly dependant on the MC and it is not only the neck heel that does the changes. The Cannon study with Carlson et al is interesting in that respect. But it is kind of meaningless in the big picture. Because the changes in that study are all too small to be used for statistical regression and predictions of what happens in real conditions over larger MC variations. Interesting enough for the museum applications etc, but not for violin makers in general, nor for science, in my opinion. Yet another of these publications of things done to famous instruments and so gets easuily published (sorry Bruce). This needs to be done over with larger variations of the RH and EMC.

 

The Itailian scientists try to be smart with sensitive instrumentation, but I think we need 3D technology that can make the studies more sexy. In My opinion optics is the answer. Interfermometric techniques. Molin did some interesting studies once with electronic speckle pattern technology and CCD cameras, and Jansson and Molin did it with the good old fashion photographic holographic techniques around 1970. Today this can be done in 3D.