Violin Forum/Message Board

[John Cadd]

Here`s one to drive you crazy.If you think of a cross section of a violin plate,what is the most efficient way to use up as much energy (turned into sound )as possible? Is a steady decrease in thickness the most efficient? Forget the curves for now , just think of a straight taper.Have you ever compared the taper to the shape of a bow.Thicker to thinner.The bow is accepted to have an efficient shape for its purpose.Mainly this purpose is a type of discrete vibration.There is a very particular way to adjust the bow thickness along it`s length.
What mathematics have been applied to such a question?
If no good instruments had ever been made would you worry about this? If so why, and if not , why not?

[FiddleDoug]

A straight taper on a complexly curved object is a bit tough! Where would you place the thickest point? At the center? At the soundpost? Also, if you taper all the way to the edge, it would be pretty fragile in that area. Some (mostly old, less expensive) violins have pretty much the same thickness all over.
_________________
Doug Wall

www.wallindependent.com

[John Cadd]

Thinking the way the mathematicians do it`s best to start with a flat straight piece of wood just to get the basic feel of the idea.
If you started with a thin area at the bridge you would quickly run out of steam as the effect would be like the tail wagging the dog.(I`ve been waiting to get that analogy in.)
Only a steady thickness or a reducing thickness would seem to make sense to me.Anything so thin that it would break is not needed in this test. As the wave moves through the wood it is continuously losing energy.Also the wave is spreading out.Each stage leaves the wave with wider areas to move and reducing energy available.The edge must also be strong enough to support the structure at all times.
The way Mathematics rules every aspect of physical vibrations reminds me of the curtate slope next to the straight even ramp.A ball will always get to the bottom first on the curtate curve.
That idea is only jogging my elbow ,so to speak.
The best result would be to get the widest areas moving with the biggest release of energy.Making the wood thin too early would give up energy too early.Volume would drop off.
Maybe to think of an imaginary type of wood first where all the waves were progressing in a perfect circle would make matters clearer.The increasing area moved is less complicated to think about.
In a way to just settle for a straight even thickness without thinking about it would be what?----Easier --more profitable--quicker--boring--timid--certain to win a gold medal--just right for the school kids --or just plain lazy.? Take your pick.

[Michael Darnton]

You should pop on over to the Maestronet Pegbox forum to put your ideas forward--there's a group over there that digs that kind of stuff that you're thinking about.
http://www.maestronet.com/forum/index.php?showforum=4

[CT Dolan]

And when you tire of that (as I have, not for want of learning, information, nor passion, but for practical reasons), you can pop back in over here where you'll find real "meat and potatoes" stuff, something to sink your teeth into, information with substance that really "sticks to the ribs", the kind that matters when you finally start cutting wood.

[mr_violin]

Amezcua

Wouldn`t you think that out of the 1,000,000s of violins made in the world so far. that some one would have tryed that taper method of yours by now.!!??
I did!! That is when I was thinking I could outsmart all the best violin makers in history!! That was on my first violin. It did not work very well!!
Amezcue,
Why not just look at the best violins .Try to copy them. When you can get there sound, then you can try to improve on that!!!

[Dave Chandler]

I've been told that the Chicago School teaches (this is heresay of course, I've not attended) to make the top approx 2.5mm all over, except (thinking of the top now as 4 quadrants, upper left, uper right, lower left and lower right quadrants) four quarter size area at the midpoints of each quadrant which are made about 2-3mm thinner. Is the purpose then, that each of these quadrants act then like four seperate speakers when energized? Do these thinner areas act to create a focal point like the center cone of a speaker, thin enough to get the vibrations initiated and from there radiate outward within the quadrant?
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[John Cadd]

Luthiers anywhere should "dig" this question.Boil down the answers so far.Current result-----Don`t know. Why? ---Never thought about it.
Any kid building a soapbox racer would try harder than that.
You are all hiding your secrets.Come on spill the beans.

[John Cadd]

For Dave Chandler
I missed a detail of your post .You used the word quarter.Being English I didn`t ,at first,realise you meant the coin.(as in $ US)
Then you mention the word " radiating ". The vibrations are all radiating outwards from the bridge.Not back towards the bridge unless there is some reflection from the sides.( Not a lot).
The Chicago method sounds like my "crackpot theory " idea of the Stradivarius pattern.
The thicker centre divides the plate which weakens any crossover vibrations.The thinnest areas are giving out most sound ,I presume.
As the wave gets near the edge we have to think about the structural strength again.So a taper needs to go only part of the way.
Must look up the diameter of a quarter.

[Michael Darnton]

[CT Dolan]

I as much as anyone want to understand the fundamentals (the nature and origin of our subject, as well as the "how and why"), but I have come to learn of the need to get some basic points down pat, some real and practical experience before I can really dive into the deeper aspects of our subject. I recommend anyone interested do the same because here we have the opportunity to be taught (which is to say to gain an understanding and with this an appreciation) through our doing. We're not talking about the realm of Quantum Field Theory here, we're dealing with tangible objects so take advantage of the fact that you can actually lay your hands on these things, and do your own work!

[rs]

By tapering, Amezcua, I am assuming you mean graduation. Generally, violins are best dealt with individually.

I found through ALOT of experimentation, that three things impact the tone of the fiddle more than others. First is uniformity to the top. Second is that the back is tuned to compliment the top, not indepentantly from the top. Third, the fiddle in the white should then be adjusted to compensate for the weight of the yet to be applied varnish.

When I consider the the graduation and arching, the first thing I consider is the spring constant to the wood. Makers will note that generally well-flamed maple is easier to bend than clear maple. This is because, as a rule, the flamed maple tends towards a lower spring constant than clear. This means that flamed is not as "stiff" as clear. What does this mean in practice? Plenty. Flamed backs must be arched higher, or thinned more, than clear, to compensate for this discrepancy. If not, the tone will be masculine and not very attractive.

The top, if not uniform in all quadrants, will have good and flabby notes. In other words, it will be common. Uniformity is more than just graduation, as each ring in the tree is slightly different in density than juxtaposed rings. The maker, if he compensates for this, will find his fiddle to have good tone across the whole register, not just hit and miss. This observation greatly improved my fiddles.

The fiddle in the white can be adjusted from the outside for final tone. If the tone sounds good, then varnish applied to this fiddle will destroy the tone. The fiddle before it is varnished will give the best results if the wood is thinned a little more to offset the weight the varnish will add. In other words, it should be thinned to a slightly metallic sound in the white. The weight of the varnish will restore the tone. Otherwise, a good fiddle in the white after the varnish is put on will sound masculine.

All of these observations, and many more, are the result of over thirty years of experimenting. They are also counter-intuitive. I found when I quit "thinking violin construction" and experimented with violin construction, my results were satisfactory.

Other than that, I pretty much agree with Michael's observation and consider it a lion's den!

Best wishes

[Janito]

If flamed maple is less stiff, why should it be thinned more than unflamed "to compensate for this discrepancy"?

[rs]

The reason is to compensate for the lower spring constant.

In physics, essentially four dynamics effect frequency. They are:

1) Mass
2) Spring constant
3) Force
4) Damping

Forgetting points 3 and 4 for this response, mass and spring constant tend to be offsetting. That is, the higher the mass, the lower the frequency, the higher the spring constant the higher the frequency.

The simplest way to see these two points in action is to pluck a string. If the E string is plucked after being tuned to E, an E is produced. If a G is desired, the fiddler can drop his second finger down and produce a G. This is because the shorter stop has decreased the mass of the string between the bridge and stop producing the G, a higher frequency than the E. In this analogy, the spring constant has not changed. The mass has decreased.

Another method to accomplish the G is to leave the stop alone, that is, leave the string open between nut and bridge, and tighten the peg. In that instance, the mass remains the same, but the higher tension has produced a G over the same distance that previously had produced an E. In the second analogy, the mass has not changed, the spring constant has increased.

Note that EITHER approaches, that is, lowering the mass while leaving the spring constant untouched, or raising the spring constant while leaving the mass untouched, changes the E to a G.

A maker must take this into consideration when constructing a fiddle.

If wood with a low spring constant is used, for lack of a better adjective, I used "stiffness" to describe wood with HIGH spring constant, then this lower spring constant will make the fiddle "low" or masculine to dead in tone IF one or both of two things are not done to compensate. One is to raise the spring constant, that is, to increase the arching. The second is to lower the mass, that is, to thin the plate a little more than wood with a higher spring constant.

In my opinion, this actually works to the maker's advantage with flamed maple, (and flamed maple DOES demonstrably tend to be a lower spring constant than clear). This is because I personally like the look of a fiddle with just a little higher arch to the back. I am not talking bad Stainer copies arching! Just a little more curve at the waist. Secondly the thinner plate makes the fiddle lighter overall.

All of this may seem moot when the fiddle is finally strung up, as it will most likely need final adjustment anyway. But those parameters helped me alot. And I just wanted to pass them along.

[Janito]

Thanks.

It is often said that the function of the back is to support the soundpost and allow the bridge to rock on a 'firm' right foot.

The thinning of a flamed back plate would reduce its mass, and also its stiffness, thus reducing support for the soundpost.