Are f-hole wings tweeters?

[Anders Buen]

If I may join this interesting discussion  I think f-hole wings are tweeters, but mostly depending on the < 600 Hz body modes (A0, B1-, B1+). If we learn how to control the pitch and deltas between these modes and relative dB deltas between them, I think we have the equalizer we need to control the sound spectrum.

 

I have experimenting with moving the modes, by attaching lumps of clay in different places, while playing the violin. It seems that this has the most significant shift in sound (and spectrum), than anything else.

 

BodyModesEqualizer.jpg

 

I guess this fiddles frequency response up to just above 1kHz looks pretty ok. The B1+ is a little on the stiff side. And there is a good gap and balance between the B1 modes. I think there might be some merit for the frequency distance between the B1- and the A0 as indicating something about the low frequency response. The B1- lie close to the open A, which makes a "lively instrument" while plaing the open A. It will probably vibrate quite strongly in the grip and chinrest at that note.

The level difference between the transition hill resonance and the A0 indicate an Dunnwald L parameter around 25dB, whic is quite typical for the great modern makers and the old great instruments. This is a necessary but not a sufficient quality I think. And it will depend on the quality of the excitation. It needs to be relatively flat over the frequency range from 250Hz to 1,1kHz.

How is the instrument held and how is it excitated to make that response? A fingersnap on the G string side of the bridge and holding the fiddle by its neck damping the strings?

[Carl Stross]

Patrick:

 

The biggest problem I have with your overall approach is that it requires the plates to be finished (and you say also varnished) before assembly.

 

Lots of very compelling scholarship thus far suggests that the Cremonese method did not purfle the plate till it was on the body, and left the edge work fairly generous leading up to that stage of construction.

 

This means that the plates could not possibly have been varnished before they were glued on the body, and that they could not have been "tuned" prior to assembly if plenty of wood still had to be removed in the process of purfling installation and edge scoop excavation.

 

Best regards,

 

E

 

What's reality got to do with anything ??!

[Carl Stross]

I guess this fiddles frequency response up to just above 1kHz looks pretty ok. The B1+ is a little on the stiff side. And there is a good gap and balance between the B1 modes. I think there might be some merit for the frequency distance between the B1- and the A0 as indicating something about the low frequency response. The B1- lie close to the open A, which makes a "lively instrument" while plaing the open A. It will probably vibrate quite strongly in the grip and chinrest at that note.

The level difference between the transition hill resonance and the A0 indicate an Dunnwald L parameter around 25dB, whic is quite typical for the great modern makers and the old great instruments. This is a necessary but not a sufficient quality I think. And it will depend on the quality of the excitation. It needs to be relatively flat over the frequency range from 250Hz to 1,1kHz.

How is the instrument held and how is it excitated to make that response? A fingersnap on the G string side of the bridge and holding the fiddle by its neck damping the strings?

 

One can but dream of the day when all violins will be bought on the strength of these...

[David Burgess]

After thinking some. I would repeat my plea to those who do such things as "testing" to come up with a set of universal international, temperature,humidity and mc readings for doing tests. Without it, it seems referring to, trying to correlate with, and comparing to other tests done is somewhat detrimental in that unless everyone is at the same exact readings, with proper 72 hour+ acclimation, the data will always be different or not sufficient for comparison. It really doesn't seem like that big of a challenge,.

 

A couple of points:

 

When borrowing someone's Strad (or such), often there is a very limited time window to take measurements.

 

Some of these instruments sound pretty good under a wide variety of conditions, so while I agree that standardization would be nice, it may not be necessary when trying to understand "the essence" of a good sounding fiddle.

[Oded Kishony]

In my experience the factor that determines the sound quality and timbre of an instrument is the relative amplitude (loudness) of the resonant peaks of the sound spectrum. 

 

This means the perceived sound of a violin can change dramatically with very small changes in the amplitude in the spectrum or it may be perceived to change hardly at all with rather large changes in the spectrum.

 

The perception of change in due in large part to pschoacoustic phenomena. By psycoacoustics I'm referring, by example, to the well known effect of having a rather low radiation of the fundamental  G frequency (196Hz) on most violins yet no one seems to have any problems identifying an open G string.

 

In other words the brain reorganizes the perception of the timbre based on the relative loudness of  the frequencies in the spectrum . I would go out on a limb and say that most violins have plenty of frequencies available the challenge is to get the right mix to project.  

 

There are other very important characteristics of a violin not measured by spectrum charts. Some instruments are just a lot of fun to play. And playing is mostly what we do with a violin   

 

 

Oded

Edited February 8, 2013 by Oded Kishony

[jezzupe]

In my experience the factor that determines the sound quality and timbre of an instrument is the relative amplitude (loudness) of the resonant peaks of the sound spectrum. 

 

This means the perceived sound of a violin can change dramatically with very small changes in the amplitude in the spectrum or it may be perceived to change hardly at all with rather large changes in the spectrum.

 

The perception of change in due in large part to pschoacoustic phenomena. By psycoacoustics I'm referring, by example, to the well known effect of having a rather low radiation of the fundamental  G frequency (196Hz) on most violins yet no one seems to have any problems identifying an open G string.

 

In other words the brain reorganizes the perception of the timbre based on the relative loudness of  the frequencies in the spectrum . I would go out on a limb and say that most violins have plenty of frequencies available the challenge is to get the right mix to project.  

 

There are other very important characteristics of a violin not measured by spectrum charts. Some instruments are just a lot of fun to play. And playing is mostly what we do with a violin   

 

 

Oded

Really I think the answer to all of this lies in this article.

 

http://scienceblogs.com/cortex/2007/11/02/the-subjectivity-of-wine/

 

I have a feeling that if we did some of these same "tricks" with violins instead of wine I KNOW we would get the same results

[Patrick KREIT]

A couple of points:

 

When borrowing someone's Strad (or such), often there is a very limited time window to take measurements.

 

Some of these instruments sound pretty good under a wide variety of conditions, so while I agree that standardization would be nice, it may not be necessary when trying to understand "the essence" of a good sounding fiddle.

 

 

Mr. Burgess:

That’s right. What makes the quality of a fine old instrument is the wood’s hygroscopic stability, for it can no longer absorb as much water vapor as a recent instrument can. The wood has lost some of its hemicellulose that thirsts for free water. The moisture content in the wood rarely exceeds 8.5%, the mode frequencies are relatively stable, whatever the ambient humidity and temperature may be.

 

www.kreitpatrick.com

[Johnmasters]

 

Mr. Burgess:

That’s right. What makes the quality of a fine old instrument is the wood’s hygroscopic stability, for it can no longer absorb as much water vapor as a recent instrument can. The wood has lost some of its hemicellulose that thirsts for free water. The moisture content in the wood rarely exceeds 8.5%, the mode frequencies are relatively stable, whatever the ambient humidity and temperature may be.

 

www.kreitpatrick.com

 

That would be consistent with what Nagyvary says.  He advocates soaking wood in borax.  The boron will cross-link hemicellulose and perhaps take up some of the sites that attract bonded water.

[jezzupe]

In my opinion photo degradation based on UV radiation is what is effecting the hemicellulose and causing internal "fractures" that change the bound water % and the woods ability to hold and absorb vapor. Here again to me it's not what the Strad is doing when it is tested, it is that if we are trying to precise with measurements, and going to compare these measurement, to me it is paramount that all tests be done under the same parameters lest we all have slightly different data .

[Anders Buen]

Mr. Burgess:

That’s right. What makes the quality of a fine old instrument is the wood’s hygroscopic stability, for it can no longer absorb as much water vapor as a recent instrument can. The wood has lost some of its hemicellulose that thirsts for free water. The moisture content in the wood rarely exceeds 8.5%, the mode frequencies are relatively stable, whatever the ambient humidity and temperature may be.

 

www.kreitpatrick.com

This is probably not correct. Look up Rex Thompsons articles on the subject.

Or just follow the weight variation of old and contemporary violins.

[Carl Stross]

Sorry to butt in but in the end, what's the conclusion ? Are f-holes tweeters or not ?

[Don Noon]

Not.

[Patrick KREIT]

This is probably not correct. Look up Rex Thompsons articles on the subject.

Or just follow the weight variation of old and contemporary violins.

 

 

I have had Rex Thompson’s paper for a long time: that is what inspired me to verify the “variation” (in my previous writings, amplitude or spread) in frequencies. I also possess your article. A calculation by percentage does not work, for the system is not linear: the variability in the materials is too

great.

Post 181, same thread: “On a recent instrument registering between 12% and 0% moisture content in the wood, the B1- and B1+ mode frequencies have an amplitude (spread) of approximately 32 Hz. 

In plates of 150- to 300-year-old instruments, the frequency spread is less (the moisture content in the wood rarely exceeds 8.5%):

the spread of the B1- and B1+ mode frequencies is approximately 16 Hz for moisture content between 8% and 0%.”

This research was conducted on old instruments that belonged to me.

However, one never leaves a violin such as a Stradivari or any valuable instrument in extreme conditions of dehydratation (0% moisture content in the wood). Generally, the wood on old instruments will register between 6% and 8% MC, and therefore, the “variation” in the B1- and B1+ frequencies will be approximately 8 Hz, which represents a good level of stability in the frequencies, compared to a new instrument, in which case the same mode frequencies, between 6% and 12% MC, can display a “variation” in frequency as great as 18 Hz, and as great as 32 Hz for MC changing from 0% to 12% (or vice versa).

www.kreitpatrick.com

[Anders Buen]

I do not even care to read the whole post, Kreit. Old wood does not behave much different from new dry wood, period.

[Anders Buen]

Sorry to butt in but in the end, what's the conclusion ? Are f-holes tweeters or not ?

They are both.

[Wolfjk]

 

I do not even care to read the whole post, Kreit. Old wood does not behave much different from new dry wood, period.

Perhaps you're not old enough to know?

[Anders Buen]

 Perhaps you're not old enough to know?

- And you are too old to remember? 

 

But yes, I do know because I have done measurements on this and have a pending publication on the issue for the VSA Papers. I was asked, in public, by the editor to write the article after my presentation at the Oberlin 2009 Violin Acoustics workshop on the same theme. I believe not necessairily because it was so scientifically stringent, but I did a fairly thorough literature rewiew and the data are showing moisture content in wood to be as a major effect for both the acoustics and other issues in the preservation and setup of the instruments. It simply is useful information to discuss and know something about for instrument makers and researchers! I guess many of us have some (bitter) experiences with instruments that are shipped to different environments than they were originally built in and for. Not taking this into account is simply not a good business plan for a musical insturment maker.

 

A good trade article on the subject is in the IPCI volumes written by Petr Buchinsky. I bought the two volume set to have that article at hand while I was writing. Now there are much more experienced personal here on MN than me on this issue like David Burgess and Bruce Carlson (see e.g. the published research and experimentation done on the Cannone del Gesu). The former teacher at the Violin maker school in Salt Lake, Jeff Robinson, know a lot from own experimentation. I only hope he will publish some of his findings. Those working in fine repair workshops will, of course, know. Much more than my own "rough science" results. Are old istruments more resistant to creep, arch height variations and changes in e.g. the neck projection than fresher ones? - I don't think so.

 

In Rex Thompsons 1979 article he show RH - MC variation data for old and new wood and there is no significant differece between the moisture content in the older versus the newer samples, at least not of any practical importance. I enclose a graph of Thompsons table data plotted into RH-EMC curves from B. Hoadleys book "Understanding wood" as well as some curves for adsorption, and various desorption conditions from the "Ecyclopedia of Wood" (figure 3.2). 

 

The 1756 and 1900 samples does not behave much different from the standard curves, and not much different from the newer wood samples in the set.

[Wolfjk]

Hi Anders Buen,

I commend you on your scientific knowledge and wish you god luck with researche.

Regarding old and and not so old wood, it is not easy to know or measure the differences. However nobody can argue with the Laws of Thermodynamics. The fact is that temperature changes register in wood.A 300 hundred year old  violin which has travelled the world unprotected from continental winters and summers expanded and contracted more than a recent violin made from timber that was kept away from the changing seasons in a temperature controlled store room and once completed, put in a cosy case.

You may not be able to measure the difference.

Regarding the subject of this thread, May I suggest a simple experience: lick your finger and dab it on any F-hole wing ! If it does not show any difference I'll eat my hat What you see actualy see on the computer simulation is the soundwaves exitinting from the damaged reed ends.A sound hole made with a sharper or blunter knife should also show up!

 

And you are too old to remember?

 

Unfortunately I'm old but still have an excellent memory. Since I took up playing the violin in my early 60s, I've learned to read and write music and can remember the score of several hundred pieces, classical, folk and popular music. At present I'm happy with my memory!
 

[Anders Buen]

Regarding old and and not so old wood, it is not easy to know or measure the differences. However nobody can argue with the Laws of Thermodynamics. The fact is that temperature changes register in wood.A 300 hundred year old  violin which has travelled the world unprotected from continental winters and summers expanded and contracted more than a recent violin made from timber that was kept away from the changing seasons in a temperature controlled store room and once completed, put in a cosy case.

You may not be able to measure any effect.

 

If we can't measure any effect, there is no effect. E.g. hearing is a "measurement".

[Anders Buen]

 Perhaps you're not old enough to know?

You started the bullying.

[jezzupe]

There is no universal regional MC content. If a piece of wood settles to a certain MC parameter it is simply because the wood is being kept in a regional area that has predetermined MC. I f we refer to the dept. of forestry, for example, and we look at the USA we see {as I recall} 4 distinct area's with distinct parameters. Now within all these regions there are micro climates and "pockets" of dryer or wetter areas that all determine what a piece of wood will settle down to.

 

Every country and corner of the globe has its own distinct regional Mc levels. For one to say that this violin or that violin settles to "this mc" , regardless of the age of the violin is incorrect, that is determined by where the violin resides and what the regional Mc parameters are, and how the interior environment is kept.

 

If we have a violin that wants to settle down to 6-8% MC that is simply because under normal uncontrolled conditions the violin resides in that regional MC content. I we take that same violin and send it to say Florida, and allow enough time to go by, 72+ hours, that violin will now want  to settle to 10-12 MC because the regional environment dictates this.

 

Unless one is going through great trouble to maintain a control room in order to negate regional MC parameters this is a fact that cannot be controlled.

 

 

http://www.fpl.fs.fed.us/documnts/fplrn/fplrn226.pdf

 

edit; here is another source for a good readable map

 

http://www.goldenstateflooring.com/documents/waterandwood.pdf

 

page 10/11. This is for the usa, but all places on the planet have there own regional mc and micro cliamates within those regional mc levels. Where you reside will dictate the basic parameters of the wood.

[Don Noon]

Old wood does not behave much different from new dry wood, period.

I am not yet a believer in this statement, from a theoretical standpoint.  Hemicellulose is known to be subject to degradation, and therefore the wood properties will change. 

On a statistical basis, this would be difficult to show, I think, due to the wide variation in natural wood properties.  You would need to have precise measurements of a wood sample, and then repeat those precise measurements on the same samples 300 years later.  Otherwise, the effects of age may well get lost in the noise.

 

I have a ton of data showing real, measurable changes in properties that take place in the same piece of wood due to thermal processing.  If wood is to remain physically unchanged over time, then NONE of these chemical reactions can take place.  Old wood is darker and opaque compared to new wood, so some chemical change has taken place.  I think it is quite reasonable to believe that the physical properties have also changed slightly, most likely the damping.

 

As always, I welcome any facts that conflict with my current opinions.

[Anders Buen]

I was thinking spesifically about the hygroscopic properties. I know that old wood is opaque. Damping variation will in my opinion not matter much because it is dominated by the holding for playing. The neck vibrates quite a lot for many of the modes and holding a vibrating part like a violin will dampit it quite much. This is also the reason why I remain sceptical about any chamical treatment and varnish properties effects on how the violin sounds while being played. I also think that the processed wood ends up baing just as moist as any other wood, it just takes much longer time to return to that state. The moisture pickup does not stop. Of course I may be wrong. 

[jezzupe]

I am not yet a believer in this statement, from a theoretical standpoint.  Hemicellulose is known to be subject to degradation, and therefore the wood properties will change. 

On a statistical basis, this would be difficult to show, I think, due to the wide variation in natural wood properties.  You would need to have precise measurements of a wood sample, and then repeat those precise measurements on the same samples 300 years later.  Otherwise, the effects of age may well get lost in the noise.

 

I have a ton of data showing real, measurable changes in properties that take place in the same piece of wood due to thermal processing.  If wood is to remain physically unchanged over time, then NONE of these chemical reactions can take place.  Old wood is darker and opaque compared to new wood, so some chemical change has taken place.  I think it is quite reasonable to believe that the physical properties have also changed slightly, most likely the damping.

 

As always, I welcome any facts that conflict with my current opinions.

I agree with this, when we want to look at things like this in a "visual" kind of way it is very simple to do. To not only see it, but feel it. When we have varnished wood, keep inside, with good conditions, this degradation is slowed, so in order to expedite this visual process we must do what we would not do with a "normal" piece of wood that would be kept inside and varnished. Simply either find a piece of old redwood decking or even better 3/4" fencing that has gone grey for years, say 10 years of exposure to uv and weather, then simply cut a chunk of the board in half and look at the cross section. It will look like a piece of bread with a "crust" the interior will be "red" still yet all around the ring the "crust" is grey. This grey "crust" {degraded wood} has not only a color difference from uv exposure but it has distinct different physical properties than the more interior wood that has not been penetrated by uv light. It is more "punky" and dry, the fracturing of the hemicellulose within the structure effects the bound water and vapor uptake and wicking.

 

Now with objects made of wood that are varnished, this same effect happens, but 1. is not visible as "grey" and 2. the process takes much longer as the wood is not exposed to direct sunlight most times. It is the slow cumulative effect of uv exposure that changes the wood properties.

[Anders Buen]

The wood may change as it ages, but its properties does not change to something we do not find in newer wood samples, except for the light prenetration. Even if the density goes down a little with age, I do not think its hygroscopic properties changes much. High and low density wood behave similarly, so why would a small amount of mass loss change anything for the old wood?