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Scientific investigations of Stradivarius violins--an updated review article


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9 hours ago, Michael_Molnar said:

Nothing personal, but I am tired of explaining this. Please do some reading.

Nobody reads these days ... what you do is ask a question on a forum, receive a dozen contradictory but equally dogmatic responses, and then pick the one you like.

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9 hours ago, Michael_Molnar said:

Nothing personal, but I am tired of explaining this. Please do some reading.

 

1 minute ago, martin swan said:

Nobody reads these days ... what you do is ask a question on a forum, receive a dozen contradictory but equally dogmatic responses, and then pick the one you like.

I do (a lot) and I have also followed Michaels "Strad varnish quest journey". I too invest a lot of time in making and experimenting with varnish. Just didn't see the connection to dichromatism on the maple sample showed.

According to Wikipedia my varnish is dichromatic.

https://en.wikipedia.org/wiki/Dichromatism

 

 

 

 

 

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4 hours ago, Advocatus Diaboli said:

This is thread is reminding me of a concert performed at Oberlin acoustics a few years ago.  The audience didn’t know which instruments were being used for the various pieces until the end, although everyone knew there were three old Italians in the mix, including a Strad and DG.  During one of the pieces a maker turned to me and said something to the affect of, ‘whenever I hear a Strad that sounds this good it makes me want to give up’. 

Another time at a Oberlin acoustics workshop a player after blind testing a del Gesu violin said: "I wonder what recycling bin they found this in."  

This inspired me to make violins like that.

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Michael Molnar posted on the thread Varnish as usual September 7 2018

Dichroism needs a molecular thin layer to produce an angle-dependent optical wave interference pattern of colors. The constructive/destructive wave interference produces colors. Oil films on water are the best example. Varnish layers are orders of magnitude too thick for dichroic effects.

Dichromatism involves the color-dependent absorption of the varnish (pigments or dyes) coupled to the human-eye sensitivity and response: We see in three colors and in "factors", "powers", or "orders of magnitude" (non-linear logarithmic scale). As the absorption of a dichromatic layer is increased either by the viewing angle or different layer thickness,  the yellow color falls off faster than the red due to our non-linear eye-response and 3 color-band sensitivity. Thus, a thin dichromatic layer will look bright yellow and a thicker layer looks redder but darker. 

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59 minutes ago, sospiri said:

Michael Molnar posted on the thread Varnish as usual September 7 2018

Dichroism needs a molecular thin layer to produce an angle-dependent optical wave interference pattern of colors. The constructive/destructive wave interference produces colors. Oil films on water are the best example. Varnish layers are orders of magnitude too thick for dichroic effects.

Dichromatism involves the color-dependent absorption of the varnish (pigments or dyes) coupled to the human-eye sensitivity and response: We see in three colors and in "factors", "powers", or "orders of magnitude" (non-linear logarithmic scale). As the absorption of a dichromatic layer is increased either by the viewing angle or different layer thickness,  the yellow color falls off faster than the red due to our non-linear eye-response and 3 color-band sensitivity. Thus, a thin dichromatic layer will look bright yellow and a thicker layer looks redder but darker. 

I am very sure that violin varnish does not show interference colors. 

"https://en.wikipedia.org/wiki/Chatoyancy

In gemology, chatoyancy (/ʃəˈtɔɪ.ənsi/ shə-TOY-ən-see), or chatoyance or cat's eye effect, is an optical reflectance effect seen in certain gemstones, woods, and carbon fibre. Coined from the French "œil de chat", meaning "cat's eye", chatoyancy arises either from the fibrous structure of a material, as in tiger's eye quartz, or from fibrous inclusions or cavities within the stone, as in cat's eye chrysoberyl."

This is the correct explanation. It is due to maple fibers having different orientations in different regions. It is due to the wavy growth pattern of of cells. It is due to light being reflected in different directions. It is NOT due to interference color. I think dichromatism is a good term for violin makers to use. Chatoyancy would be the most appropriate term in the scientific lingo. 

 

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White light has a very short coherence length. It is of the same size as the wavelength of orange light. Very thin coatings on optics make them appear greenish, or yellowish. Some violet some orange. The thickness of the layer determine the colours. Light reflected from oil on water give similar effects. I think these layers are 1/4 of a wavelength thick.

varnish is much thicker. So the coherence is gone before the direct light meet the reflected. No colours filtering appear from this.

Particles in the varnish or elements on the surfaces start to spread light from wavelength/4, just as in acoustic diffraction. From about wavelength size they start to reflect light efficiently.

i think the nomenclature you use here chatoyance, dicroism belong to different fields in physics than describing varnished wooden surfaces. 

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1 hour ago, Advocatus Diaboli said:

The violin that was thought to be the Strad was six months old.  

So assumed -> copy the great ones not bad old cremonese

No further questions I hope :(

I'm pleading the fifth...

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4 hours ago, reguz said:

What answer actually has been scientific about Stradivaris violins and investigations?

The fame of the soloists who play them correlates with the wonderfulness of the sound of his violins.

Simple arithmetic really.

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Sospiri, You are talking about the EAR of the player. But what scientific opinion can he give so YOU can learn something making a scientific better instrument. Ears as you know function different from man to men and the judgment is thus not scientific repeatable.

 

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1 hour ago, sospiri said:

The fame of the soloists who play them correlates with the wonderfulness of the sound of his violins.

If I show up at the gym this morning driving a Lamborghini, I'll be semi-famous too. ;)

Or even if I show up with a Strad at a truck stop. "Breaker one-nine, there's a jen-wine Strad-you-various at the Baker Road truck stop."

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9 minutes ago, David Burgess said:

If I show up at the gym this morning driving a Lamborghini, I'll be semi-famous too. ;)

I thought you had a Lambo, A Ferrari and a Maserati? And those were just the Italian motors you owned?

 

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21 minutes ago, reguz said:

Sospiri, You are talking about the EAR of the player. But what scientific opinion can he give so YOU can learn something making a scientific better instrument. Ears as you know function different from man to men and the judgment is thus not scientific repeatable.

 

I learned from Échard. His study of old Italian varnishing methods. I have been wtiting about this since I first started posting here in January 2017.

I am interested in the construction methods also. You asked "Why Arching?" I am asking: Is arching a mid range booster?

Also, does the design of Il Duomo allow a thinner and more responsive plate?

 

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1 hour ago, sospiri said:

>

I am interested in the construction methods also. You asked "Why Arching?" I am asking: Is arching a mid range booster?

>

 

Years ago I began an experiment to determine the effects of plate arching height on the various resultant vibration mode frequencies and the general shape of the frequency response curve and resultant sounds produced.  I was going to start with perfectly flat plates and then make a series of higher and higher arched plates which could be replaced on the same instrument body.  For example a top plate arch series could go 0, 4, 8, 12, 16, 20mm heights.  The back plates would go in the same sequence.  The different arches of the two plates would give 6X6=36 different combinations.  If a trend developed I could later go back and try smaller increments if an optimum appeared possible.

The simplest and first combination I tried was a flat top with a flat back (0,0).  I liked the sound very much and never bothered trying all the other 35 combinations.  All of my couple dozen subsequent violins and violas were then made with flat top and back plates.

Repeated player and listener blind tests have shown this was a bad mistake.

 

 

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On 4/21/2021 at 11:42 AM, martin swan said:

Nobody reads these days ... what you do is ask a question on a forum, receive a dozen contradictory but equally dogmatic responses, and then pick the one you like.

 

On 4/21/2021 at 1:11 PM, Michael_Molnar said:

Well said.

Hubris and petulence are equally unscientific. 

Yes wikipedia is often not a good source. But every well established belief is market driven, so we have to strive harder to get a point across if we really have faith in our opinions. Hasn't it always been that way?

Stating an opinion as fact is what causes disagreement. We either hammer it out or retreat. 

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5 minutes ago, Marty Kasprzyk said:

Years ago I began an experiment to determine the effects of plate arching height on the various resultant vibration mode frequencies and the general shape of the frequency response curve and resultant sounds produced.  I was going to start with perfectly flat plates and then make a series of higher and higher arched plates which could be replaced on the same instrument body.  For example a top plate arch series could go 0, 4, 8, 12, 16, 20mm heights.  The back plates would go in the same sequence.  The different arches of the two plates would give 6X6=36 different combinations.  If a trend developed I could later go back and try smaller increments if an optimum appeared possible.

The simplest and first combination I tried was a flat top with a flat back (0,0).  I liked the sound very much and never bothered trying all the other 35 combinations.  All of my couple dozen subsequent violins and violas were then made with flat top and back plates.

Repeated player and listener blind tests have shown this was a bad mistake.

 

 

So you like the sound, but trained players don't? 

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8 minutes ago, sospiri said:

So you like the sound, but trained players don't? 

Marty has been a bold and clever experimenter. Pretty much anything outside of "the usual", in the violin world, will not be easily accepted, as long as old Cremonese violins are (erroneously?) considered to be the ultimate manifestation.

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27 minutes ago, David Burgess said:

Marty has been a bold and clever experimenter. Pretty much anything outside of "the usual", in the violin world, will not be easily accepted, as long as old Cremonese violins are (erroneously?) considered to be the ultimate manifestation.

So when we're standing on the shoulders of giants, do we have to pick n choose da bestest giant?

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