Graham Caldersmith's free plate and assembled violins data - Correlations

[Don Noon]

6 hours ago, Anders Buen said:

I do not think the Vieuxtemps del Gesu is a particularly interesting instrument. 

I think it's interesting in that it's something of an outlier acoustically... and we have good data on it.  It's not my favorite fiddle tonally, but for punching through an orchestra, it's probably pretty good.

2 hours ago, Marty Kasprzyk said:

Precise 2.0 ratios (octave) of mode frequencies should be avoided. 

Meh.  That's a good idea, but not a big deal unless you don't have enough overtones to even things out.  Here's a fiddle of mine where B1+ is almost exactly an octave above A0.  It only matters (slightly) with some excess strength at C# on the G string.  See if you can pick it out; I can't.

https://www.youtube.com/watch?v=PYOsaWsxklA

[Marty Kasprzyk]

1 hour ago, Don Noon said:

I think it's interesting in that it's something of an outlier acoustically... and we have good data on it.  It's not my favorite fiddle tonally, but for punching through an orchestra, it's probably pretty good.

Meh.  That's a good idea, but not a big deal unless you don't have enough overtones to even things out.  Here's a fiddle of mine where B1+ is almost exactly an octave above A0.  It only matters (slightly) with some excess strength at C# on the G string.  See if you can pick it out; I can't.

https://www.youtube.com/watch?v=PYOsaWsxklA

There's probably some level of badness that it becomes a problem for the player but maybe not for the listener.

I'm guessing that the Strads that Saunders tested in 1937  might have been pretty good but he had some comments on them.

Saunders, 1937.pdf

[Marty Kasprzyk]

On 3/17/2024 at 10:22 AM, Anders Buen said:

I bought a couple of series of instruments made in Weihai, China some years ago. It is on the east coust and I think it is pretty humid there. It is humid in Cremaona too. My frends cello cracked when it came home to our dry winther climate, after a few months, I think. So for the customers from Scandinavia, Cremona is not really a agood place to run a workshop from.

Now to the case. I bought these violins because I needed data points for my «data mining project». The prices were reasonable and the quality quite good. You can choose of course, related to the price. I bought some finsihed and varnished and some white. The finished ones can be played before regreaduation, and it is easy to get the signature modes on FFT, «mobility» or SPL/F.

I have done this over many many years, along with a small business in the same, where instruments came in for repair etc. Doing so mapping instrument properties, you see trends after a while.

In general the chinese violins are relatively solid built (not all of them) and tend to have high lying signature mode frequencies. A few out of say 20 are great as they are. But the regraduated ones get more low frequency punch and, possibbly looses a bit of the highs.

I think there is plenty of evidence that thick mass produced or just thick solid built insturment do sound stiffer and may benefit from being thinned a bit. There is evidence also in Moral and Janssons work on this from the 80ties. At least they manged to get «rules» that would separate the winners from the «loosers» in the FIOL 80 or whatever year competition. 

Players prefer different instruments, so a competition resiult will be the preferences from the judges, and not a universal judgement. It is all subjective, but with different degrees of objectiveness. Absolute objectiveness does not exist. 

Have you looked at Doug Cox's data too?  I remember that he kept very detailed records.

[Anders Buen]

4 hours ago, Marty Kasprzyk said:

Have you looked at Doug Cox's data too?  I remember that he kept very detailed records.

Yes and no, I haven't looked at his data lately. But did record a lot of soundspeeds when I visited his workshop. He did, and probaly still do, record a lot of acoustic data along with graduations and pictures. Very systematic. 

[Peter K-G]

I don't have deep knowledge in statistcs, but I imagen it would require huge amount of data to get reliable results with quantitative research.

Collecting data from different sources and not knowing humidity of free plates nor assembled violins humidity, measuring errors, change over time from free plate to measuring body modes and so on..

 

[Anders Buen]

2 hours ago, Peter K-G said:

I don't have deep knowledge in statistics, but I imagine it would require huge amount of data to get reliable results with quantitative research.

Collecting data from different sources and not knowing humidity of free plates nor assembled violins humidity, measuring errors, change over time from free plate to measuring body modes and so on..

 

it is a game of trial and error. It is essential to include data that may be important for the prediction. like the plate sizes. Humidity would be nice to know, but for most data that is missing. The most relevant and ideal would be the elastic parameters, densities/weights, the graduations, free plate tones, the RH and the dimensions taken at equillibrium for all.

Ill see what I get. I have a FEA model of violin plates and can supplement with calculations. All I need is to improve my former flat equivalent plate model, corrected using Shumachers half cylinder FEA results from JASA. 

With what I have right now, about 300 + data lines for the backs, maybe some 60-70% of the variation may be explained. But we will see. I think the properties of the backs have been overlooked in the violin acoustics community. 

There are a significant correlation between top and back plate average graduations for Strads and del Gesus I have graduation data for, some 127 ish now. Im planning to do older type violins too.  

Edited March 19 by Anders Buen
Added a number

[LCF]

@Anders Buen  there is a paper in statistics you might like. It's a freely downloadable pdf of the 2001 PhD of Joseph Beyene titled "uses of the fft fast fourier transform in exact statistical inference"

 

It's too big to send and I can't copy the url here on my phone but google will lead you to it.