Jump to content
Maestronet Forums

Wood treatments by Stradivari and Guarneri


Bruce Tai
 Share

Recommended Posts

My dear friends, I have been talking about a study analyzing the spruce soundboards of Cremonese masters for several years. 

It is now published in Angewandte Chemie, one of the top three chemistry journals out there (files attached): 

https://onlinelibrary.wiley.com/doi/10.1002/anie.202105252

We paid $5000 for the open access option so that everyone can read it. We also made an Excel spread sheet containing all the ICP-MS data but it does not seem to be available yet. I will ask them why. 

There is a plan to write an accompanying article in the Strad to better explain the findings to luthiers. Your suggestions on what I should explain further would be appreciated. 

 

Also, we must not forget that Remy Gug correctly predicted 80% of our findings more than 30 years ago, in his two Strad articles:

Salts of Wisdom (1987, issue 1166)

Salted Soundboard and Sweet Sounds (1991 issue 1214). 

Anyone knows how Remy Gug got it so right? Many people have told me many theories about Stradivari's secrets. Gug made the best predictions so far. 

 My Xerox copies of these two articles have shown wear and tear. I would appreciate if anyone could scan them as PDF and send the files to me. Thanks in advance. 

1980445727_2021AngewStradSpruce.pdf 1132972592_2021AngewStradSpruceSI.pdf

Link to comment
Share on other sites

  • Replies 68
  • Created
  • Last Reply

Top Posters In This Topic

Thanks for the post. It was especially generous of you to make the research free for public viewing.

I was wondering why a paper filled with meticulous scientific measurements would start with multiple controversial claims like, "Despite tremendous advances in sciences and arts since the industrial revolution, violin making represents a singular case that has undergone a functional decline."

I won't rehash the controversies surrounding the old vs. new debate. A search will reveal copious discussions on this topic. Starting a serious scientific report with such heatedly disputed claims would suggest a confirmation bias that does not seem to have any real connection to the actual investigation.

You found obvious differences among the wood in SOME old instruments and new wood. There was even variation among the old instruments. Maybe a few of the differences were due to natural aging. Maybe a few were due to intended or unintended wood treatments. How any of this is related to things like quality of tone, projection and playability was never made, even in a cursory fashion.

Did you really need to make those statements in the introduction? 

Link to comment
Share on other sites

Yes, the underlying Cremonacentric bias still comes through, additionally with the choice of some words implying sophisticated intent, such as "manipulated" and other similar terms.

However, overall I sense that the bias has been dialed down significantly, compared to previous over-the-top worship papers.  And there is more emphasis on the use of detected chemicals as mundane preservatives, which IMO they most likely were, rather than high-tech wood modification experiments for tone enhancement.

The most relevant observation for me is that the half-life of maple hemicellulose is so much shorter than of spruce, which I have suspected for some time is behind some of the frequency response differences exhibited by very old violins.  I'm not claiming I'm right, though.  Well, maybe I am... until proven otherwise:)

Link to comment
Share on other sites

1 hour ago, Don Noon said:

>

The most relevant observation for me is that the half-life of maple hemicellulose is so much shorter than of spruce, which I have suspected for some time is behind some of the frequency response differences exhibited by very old violins.  

>

How do the frequency response of very old instruments differ from new ones?

Link to comment
Share on other sites

Bruce, Thanks for making all research results accessible.

Decline?

We have to see as well that there were makers in the 20th century (Ansaldo Poggi for example) who were categorized in acoustic research in the ‘Strad Guarneri group’ and certainly did not employ such wood treatments. 
 

In total I see in the article the assumption that Cremonese makers were only able to make extremely thin soundboards (and thinner than any modern maker) because wood was treated and this became a major factor to have the resistance to withstand the pressure of the bridge equivalent to approximately 8kg. This is however on modern setup with modernized string angle and high tension strings. This was not foreseen by Cremonese makers. In contrary I see a permanent development in adjusting those famed instruments to diminish the pressure from the bridge (reflected in the development of the neck over stand) and I would not be surprised if with the further recent development of strings this measurement will be raised again to compensate over pressure from the bridge. (There were makers past and present who dared to make top plates as thin as Strad or Guarneri) 

I think your term of ‘unique properties’ describes the phenomen the best. If this is however in an artistic field the objective measure for a peak after which only a decline is inevitable is in IMO in scientific terms questionable.

I see the perception of violin sound as a process. Many seemingly contradictory experiments with sound perception show mostly that the ‘ideal sound’ does not exist. (No miracle)  We can ask ourselves the question if in a purely artistic sense the Strad sound is still the best to express emotions written in music in the 20th century. 

In those terms research should focus on the uniqueness without trying to proof any ‘better’ or ‘worse’. So for further explanations it would be really interesting to know what can be done with wood treatments and this should be interesting enough. What makers in the future decide to do with their wood is always a choice based on personal experience. Looking forward to more details on the topic of ‘uniqueness’ in your research.


 

 

Link to comment
Share on other sites

4 hours ago, Marty Kasprzyk said:

How do the frequency response of very old instruments differ from new ones?

That information has now been out there for over 30 years, first published by Dunnwald in CAS May 1991, and pretty much confirmed by Anders Buen, my own measurements, and Joseph Curtin's data.

When it comes to the cause, how easy it is to hear, and whether it's preferred... that's where all the noise comes in.  But to my knowledge, the difference in response (on average, not every instrument) has remained true.

Link to comment
Share on other sites

6 hours ago, Don Noon said:

That information has now been out there for over 30 years, first published by Dunnwald in CAS May 1991, and pretty much confirmed by Anders Buen, my own measurements, and Joseph Curtin's data.

When it comes to the cause, how easy it is to hear, and whether it's preferred... that's where all the noise comes in.  But to my knowledge, the difference in response (on average, not every instrument) has remained true.

Dunnwald doesn't show that the wood's aging has an important effect.  He said:

"The old Italian violins are good not just because they are old.  There are many other instruments that are also old but they are bad, and there are many new violins that are very good."

"The final results show that all groups of instruments (factory, hobby, master, old Italian, and new) contain very good violins, but the relative number is different in each group.  The distribution of results of factory and master instruments is random, that of the the old Italian makers is not." 

"The reason for these results seems to be special knowledge among the old Italian makers."  

However I believe Dunnwald was "cherry picking" his instrument selection groups to show this. "One lot of instruments being known as having excellent sound (about 50 old Italian violins an others) was used as a reference group."

But there are about 500 violins made by Stradivari that are known to still exist.  You could do the opposite and pick the 50 worst ones and compare them with the 50 best modern violins and conclude modern makers had "special knowledge" that Stradivari didn't have and/or that old wood isn't as good a new wood.

 

 

Link to comment
Share on other sites

19 minutes ago, Marty Kasprzyk said:

"The reason for these results seems to be special knowledge among the old Italian makers."  

That's where the debatable part comes in.

21 minutes ago, Marty Kasprzyk said:

But there are about 500 violins made by Stradivari that are known to still exist.  You could do the opposite and pick the 50 worst ones and compare them with the 50 best modern violins and conclude modern makers had "special knowledge" that Stradivari didn't have and/or that old wood isn't as good a new wood.

I have tried to take measurements on every old fiddle I have come across, including a great Strad, middling Guarneri, mediocre Strad, Amati, a couple of unremarkable Carcassi's, and some non-Cremonese from the early 1800's.  From what I have seen, ALL of them show response features of the "Old Italian Sound", even if they aren't very good sounding.  I have also taken many more response plots of many more modern instruments (late 1800's to new), and maybe 2 or 3 of them show some of the features of the OIS... but not all features.

I have convinced myself that age is strongly correlated with these response features, but if you want to believe in the "special knowledge" or "cherrypicked examples", disproving those theories is practically impossible.

Link to comment
Share on other sites

1 hour ago, Andreas Preuss said:

Are those response features the signature modes?

From the referenced CAS article by Dunnwald:  "All curves are similar in the lower frequency range, up to 700 Hz".  So, since the signature modes are below 700 Hz, no.

Here is a difference comparison of the 4 violins on your "bench" thread, full bowed scales.  I used the 1638 A. Guarneri as a baseline, and plotted how the other 3 violins differed from it.

(There seems to be a problem with MN where I can't upload the plot... I'll try again later)

Anyhow... all of the modern violins display more power than the Guarneri in the zone around 1 kHz (the nasal, bad band) and above 4 kHz (the harsh, bad band).  So although the Guarneri should have less overall power, the tone is more desirable according to the Dunnwald criteria.

Also of note:  the Lightweight violin has a ton of power in the low frequencies, and the Pareschi is extremely weak there.  The French Factory violin most closely matches the Guarneri... but not quite in the frequency bands noted above.

 

Link to comment
Share on other sites

Since we have analyzed a bunch of aged tonewoods from antique Chinese zithers, we have now further insights into wood aging.

By antique we mean softwood up to 250-2250 years old; hardwood from 250-700 years old. We also did artificial aging. 

Hemicellulose in hardwood decomposes more easily in natural aging.

Softwood cellulose rearranges more easily in artificial aging. (This will be published in a couple of years)

Antique Chinese zither makers were pretty crazy in both artificial aging and using very old wood (>500 years) . 

It may not be totally crazy to think that the soundboard can survive 1000+ years in violins.  But I doubt that the maple back will last more than 600 years. When we recorded violins from 1560 and 1570 in my Savart Journal paper, they seem to be fine. So 450 years is still OK for maple. 

Link to comment
Share on other sites

Endless debates on who is the peak and who sounds better seems futile, I think we should be debating the thickness pf soundboards, because it is measurable.

Let me quote from the Hill book on Stradivari:

"It has at various times been asserted that Stradivari erred in the adjustment of his thicknesses, and made his instruments too thin. Fortunately, such statements invariably proceed from persons whose knowledge of Stradivari's work is very limited. The more thought we give to the subject, the more reason we see to hesitate in speaking positively for or against such a view. "

I cannot find any other source willing to discuss this issue in a straightforward manner. 

Did Stradivari make his soundboard thinner than modern makers on average? 

I am sure some modern makers tried to copy Stradivari's extra-thin soundboard (2.0-2.4 mm in center). Good results or bad results? 

 

 

Link to comment
Share on other sites

13 hours ago, Andreas Preuss said:

We have to see as well that there were makers in the 20th century (Ansaldo Poggi for example) who were categorized in acoustic research in the ‘Strad Guarneri group’ and certainly did not employ such wood treatments. 

 

Hi Andreas, 

Do we know that Poggi used natural wood?

Do you think he has any secret? 

 

Link to comment
Share on other sites

22 hours ago, Bruce Tai said:

Hi Andreas, 

Do we know that Poggi used natural wood?

Do you think he has any secret? 

 

Hi Bruce,

Poggi doesn’t strike me as a ‘secret guy’ However in his days some violin makers were hunting for really old wood.

For the rest Poggi had probably as many ‘secrets’ as any other violin maker, things based on his experience.

If there is anything special about his instruments, some have a very low arching, lower than standard. I take this as indication that he was interested in structural fine tuning with arching height, top plate thickness and string angle. 
 

Edited by Andreas Preuss
Grammar correction
Link to comment
Share on other sites

7 hours ago, Bruce Tai said:

I am sure some modern makers tried to copy Stradivari's extra-thin soundboard (2.0-2.4 mm in center). Good results or bad results? 

I tried a copy of the 1714 ex-Jackson Strad, copying the graduations (2.7 mm in the center, but below 2 mm in many other areas).  Unfortunately, I didn't know the wood density of the Strad (.34) at the time, and used .40 (torrefied) spruce.  It was too harsh, and I had to thin out the center area.

In general, I think Strad's grads are thinner than necessary, and would work just fine slightly thicker.  My nominal starting thickness for the center is 2.5 mm, but would go thinner for denser wood.

On new instruments with normal wood, I feel that they start out life slightly muted on the high end, so if you went to Strad thinness, the sound would be tubby or imbalanced toward the low end.  After aging for a while, the highs open up, and regraduation (thinning) would be needed to bring up the lows to re-balance the tone.

3 hours ago, Evan Smith said:

Don,

Do you do this by your side of bridge "Whack Job" with the 2gm hammer?

And if so where do you place the mic?

For impact spectra, my "hammer" is 1 gram.  I use 9 different mic positions (~7" from the instrument) and average them all together for response.  I also use bowed semitone scales, with one mic position 1 m away.

Link to comment
Share on other sites

Unfortunately we still don't have publicly available CT data that tell us about the weight, density, thickness, and weight at the same time. It would be important to know if the very thin Strad plates were built wit denser wood. More importantly, CT cannot reveal chemical composition. So we don't know if Stradivari also adjusted thickness according to wood treatment method. 

Link to comment
Share on other sites

10 hours ago, Bruce Tai said:

Unfortunately we still don't have publicly available CT data that tell us about the weight, density, thickness, and weight at the same time. It would be important to know if the very thin Strad plates were built wit denser wood. 

However, we do have some pieces.  For the ex-Jackson, we have CT density measured at .34, thicknesses measured by Sam Z. via Hacklinger (thin; significant areas slightly below 2 mm), and actual plate weights taken during repairs, confirming that it's very light... i.e. the low density and thin grads can't be far off.

From other information I am aware of, it looks to me like Strad made them thin without much adjustment for high or low density.  But I'm sure there are many other repair folks who could say more.

Link to comment
Share on other sites

20 hours ago, Bruce Tai said:

Unfortunately we still don't have publicly available CT data that tell us about the weight, density, thickness, and weight at the same time. It would be important to know if the very thin Strad plates were built wit denser wood. More importantly, CT cannot reveal chemical composition. So we don't know if Stradivari also adjusted thickness according to wood treatment method. 

The most complete set of data I've seen came from:

 M.A. Pyrkosz, "Reverse Engineering the Structural and Acoustic Behavior of a Stradivari Violin", Dissertation, Michigan Technological University, 2013. http://digitalcommons.mtu.edu/etds/634

Pyrkosz took the CT scans of the "Titian" 1715 Strad to show in his table 4.23 that the top plate had a density of 0.35 g/cc with a weight of 48.1g and the back plate had a 0.570g/cc density and a weight of 88.9g.  The plate thickness maps are shown in figures 4.69 and 4.70. 

With modal analysis of the various violin mode frequencies he was able to estimate the top and back wood's elastic modulus.

I think it would have been easier to cut up the violin into wood strips and test the pieces. 

Link to comment
Share on other sites

The Smithsonian published a number of interesting plate maps of Del Gesu and Strad instruments on the web about 10 years ago.

I haven't looked recently to see if they are still easily accessible, but they where.

Also, Anders Buen published some numeric plate maps in the past also.

It was the data from these sources that led me to accept that Strad tends to 'thin between the upper eyes'.  And Del Gesu does not.

Also, Borman published multiple maps of a few instruments in Strad and other places.  Some of these were density maps with good resolution.

From the combination of all these sources, I was left with the impression that the thinning thing had nothing to do with density, and everything to do with maker choice/preference.

Link to comment
Share on other sites

14 hours ago, David Beard said:

It was the data from these sources that led me to accept that Strad tends to 'thin between the upper eyes'.  And Del Gesu does not.

I have noticed from experience that thinning between the upper eyes leads to rapid arch rise and neck dropping as the stresses in the arch equalize themselves. There is a certain sound advantage to this but I would rather have longevity than instant gratification. Early on I would end up thinning there to get what I wanted out of it. In knowing what I'm looking for now, I've been able to accomplish it in other ways that allows for a much stronger box.

I've never seen this sudden arch rise and neck drop at all on a DG type arch with slightly thicker grads in the center.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.




×
×
  • Create New...