Plate Tuning the top

[Peter K-G]

8 hours ago, Torbjörn Zethelius said:

Taptones /Chladnipatterns are distractions IMO.

 

3 hours ago, Don Noon said:

That I'll agree with.

Some makers  still distract themselves with it, but they are probably amateurs

[Violadamore]

Thanks for posting that very interesting photo, @Oded Kishony.  Very nice to see you posting. 

[Marty Kasprzyk]

52 minutes ago, Peter K-G said:

 

Some makers  still distract themselves with it, but they are probably amateurs

The upper left photo is Sam Zygmuntowicz.

 

[Don Noon]

1 hour ago, Peter K-G said:

Some makers  still distract themselves with it, but they are probably amateurs

Even pro makers are humans, and can latch onto beliefs that aren't real but don't hurt.

That said, I still measure and record taptones, and slightly shade where I end up weight-wise.  It doesn't seem to hurt.  But I do like to understand what's real and what's not.

2 hours ago, Oded Kishony said:

This is exactly what it looks like if you're trying to affect the tone of the instrument from the exterior!

This only indicates final scraping after the F-holes are cut, where it's hard to get smooth near the edge.  I do that, and my wings sometimes look like that, but I absolutely am not tuning anything.  It all moves around after varnish anyway,

 

[Bodacious Cowboy]

1 hour ago, Peter K-G said:

 

Some makers  still distract themselves with it, but they are probably amateurs

I like bottom right guy. Really feeling it.

Schleske has a kind of Hendrix pose thing going on.

Davide is maybe also channeling Jimi 

[Marty Kasprzyk]

3 minutes ago, Bodacious Cowboy said:

I like bottom right guy. Really feeling it.

Schleske has a kind of Hendrix pose thing going on.

Davide is maybe also channeling Jimi 

Is the bottom middle photo Schleske?

[David Beard]

Don't forget the marketing value. It's something specisl and definite you can talk about doing.  

 

[Davide Sora]

14 hours ago, Marty Kasprzyk said:

The edges of a free plate are completely free to move horizontally, vertically, and rotationally whereas in an assembled violin the horizontal and rotational movements are somewhat constrained while the vertical movement is prevented.  So free plate testing doesn't accurately represent how the plate vibrates when it is assembled.

George Stoppani therefore developed a way of holding the free plate with an array of slender fingers around the plate perimeter which mimics the edge attachment.  This is shown at the 31:46   time in the Claudia Fritz YouTube presentation of the Bilbao Project part l https://www.youtube.com/watch?v=M0viEwUFz-o

The photo on the left shows the free plate testing set-up with the shapes of the mode 2 and mode 5 above and on the left.  The photo on the right shows George's test set-up with its resulting mode shapes which are similar to an assembled violin.

 

That's a very smart rig, and I confess that the first time I saw it (I know someone who participates in the Bilbao project) I was tempted to make one. But then I gave up because it would waste too much time and is still a surrogate, not the real thing. Certainly very useful and interesting within a research project, but less interesting in the day-to-day construction, all in all they are still free plates.

I also recalled where I had already seen the explanation of Evan Davis' formula for impedance: https://www.bele.es/en/making-tops-backs/

It doesn't seem to me anything too revolutionary, it's just an evolution of the Stiffness Number, from which I honestly can't get too much reliable information, perhaps this one can do better, maybe. In the end it's all about weight and frequencies, since I take tap tones and all other "useless" data, I think I'll add it to my measurements, you never know that something useful will come out of it

[Davide Sora]

11 hours ago, Bodacious Cowboy said:

Davide is maybe also channeling Jimi 

The problem is what I have to do whenever I'm not happy with the results, to stay in character...

[David Burgess]

4 hours ago, David Beard said:

Don't forget the marketing value. It's something specisl and definite you can talk about doing.  

 

The photos do suggest a more powerful metaphysical relationship between the maker and the instrument, than just carving wood.

[Bodacious Cowboy]

27 minutes ago, Davide Sora said:

The problem is what I have to do whenever I'm not happy with the results, to stay in character...

Move over, Rover, Let Mr Sora take over 

[Don Noon]

3 hours ago, Davide Sora said:

since I take tap tones and all other "useless" data, I think I'll add it to my measurements, you never know that something useful will come out of it

So far, most of my measurements have been extremely useful for showing what doesn't matter.

[HoGo]

16 hours ago, Peter K-G said:

 

Some makers  still distract themselves with it, but they are probably amateurs

They want to look like they know what they are doing. :-)

[Marty Kasprzyk]

3 hours ago, Davide Sora said:

That's a very smart rig, and I confess that the first time I saw it (I know someone who participates in the Bilbao project) I was tempted to make one. But then I gave up because it would waste too much time and is still a surrogate, not the real thing. Certainly very useful and interesting within a research project, but less interesting in the day-to-day construction, all in all they are still free plates.

I also recalled where I had already seen the explanation of Evan Davis' formula for impedance: https://www.bele.es/en/making-tops-backs/

It doesn't seem to me anything too revolutionary, it's just an evolution of the Stiffness Number, from which I honestly can't get too much reliable information, perhaps this one can do better, maybe. In the end it's all about weight and frequencies, since I take tap tones and all other "useless" data, I think I'll add it to my measurements, you never know that something useful will come out of it

The Bilbao project (a massive and careful undertaking) used nearly as possible identical woods for the top spruce plates and maple back plates and all the other parts.  The spruce wood and maple wood had typical densities and the plates were thinned to achieve "pliable", "medium" or "resistant" impedances.  Listener and player tests concluded a pliable top and a pliable back was most preferred which shows the usefulness of their impedance measurements.

But another project is needed to show what happens when non typical woods, either high or low densities and stiffnesses are used such as the high density spruce used for Paul McClean's plate.  

I find it is easy to suggest that other people do more work. 

[Don Noon]

8 minutes ago, Marty Kasprzyk said:

 Listener and player tests concluded a pliable top and a pliable back was most preferred which shows the usefulness of their impedance measurements.

From this test, it is not clear that the "impedance measurement" is the figure of merit, as it is a combination of mass and frequency.  If mass or frequency are dominating factors, you can't tell yet.

I too find it easy to suggest time-consuming tests for other people to do, and the most interesting tests I think would be to use different wood and try two sets:  one with identical plate masses but different taptones, and one with identical taptones but different masses.

[Davide Sora]

13 minutes ago, Marty Kasprzyk said:

The Bilbao project (a massive and careful undertaking) used nearly as possible identical woods for the top spruce plates and maple back plates and all the other parts.  The spruce wood and maple wood had typical densities and the plates were thinned to achieve "pliable", "medium" or "resistant" impedances.  Listener and player tests concluded a pliable top and a pliable back was most preferred which shows the usefulness of their impedance measurements.

But another project is needed to show what happens when non typical woods, either high or low densities and stiffnesses are used such as the high density spruce used for Paul McClean's plate.  

I find it is easy to suggest that other people do more work. 

I always take off my hat for those who face research initiatives aimed at shedding some light on the functioning of the violin, because there is always something good to learn for  us "simple" makers or at least they offer new ideas to think about. Unfortunately the conclusions of any serious research are always the same : more work still needs to be done.

As inevitable as it is irritating...

[Anders Buen]

20 hours ago, Marty Kasprzyk said:

Is the bottom middle photo Schleske?

Yes.

[HoGo]

I wonder if it is worthwhile to build such complicated rigs to measure the frequancies and still not knowing what it will sound like until the thing is finished and strung up.

There is one mandolin maker who uses a simple rig consisting of dummy rim and neck to which he attaches top and back (he uses extra overhang and tiny screws into oustide lining) strings up and he can do adjustments after playing by simply removing the back and reworking interior. This would show results much closer than any theoretical rig for measuring frequencies.

I myself string up instruments in the white and do some adjustments to thicknesses from outside (though it wouldn't be hard at all to do them on the inside). That was really eye openng thing in my building (of mandolins).

 

[Anders Buen]

6 hours ago, Marty Kasprzyk said:

 Listener and player tests concluded a pliable top and a pliable back was most preferred which shows the usefulness of their impedance measurements.

Thanks for sharing the link to the youtube video. I have been looking at some of the data from that test. It is difficult to gat a good overview without taking part in the numerous tests, a real puzzle. However, the material part is fairly easy to get a grasp of.
In general there are plenty of very clear correlations between the plate modes, the weight, the impedance formula and graduations. You can choose any you like to describe the plate. They are made of very similar wood, the same model etc to minimize that kind of variation. So the set will be more streamlined than most other sets of violin plate data. 

They have emphazised on the Davis formula for impedance as a tool. That may work well, maybe it is much faster just to do the weight, tap tones and graduations. It is just a way to make those numbers into one making it more abstract, which I think is not a good thing.  
There are many methodes that work well in making. I have seen one of the gratest do bending test of a plate I had at Oberlin, comment "stiff", which was correct. If you are trained at it you get good at it. If another tries it, it may not work. This kind of things depend on the training, skills and maybe a bit of talent. Not much kan beat the speed of tapping a plate and listening, having a control tuneable tuning fork near, the graduation meter or pounch a light source, a weight and a humidity meter. 

[Torbjörn Zethelius]

Anyone familiar with the replication crisis? 

[David Burgess]

10 hours ago, Torbjörn Zethelius said:

Anyone familiar with the replication crisis? 

Too many people getting vasectomies?

[Don Noon]

1 hour ago, Torbjörn Zethelius said:

Anyone familiar with the replication crisis? 

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

When you have wood with infinite physical variables and varnish with infinite physical variables and geometry with infinite physical variables and then judge the result with humans that have infinite^2 variables, one can not expect to replicate the results of any test.

[Marty Kasprzyk]

17 hours ago, HoGo said:

I wonder if it is worthwhile to build such complicated rigs to measure the frequancies and still not knowing what it will sound like until the thing is finished and strung up.

There is one mandolin maker who uses a simple rig consisting of dummy rim and neck to which he attaches top and back (he uses extra overhang and tiny screws into oustide lining) strings up and he can do adjustments after playing by simply removing the back and reworking interior. This would show results much closer than any theoretical rig for measuring frequencies.

I myself string up instruments in the white and do some adjustments to thicknesses from outside (though it wouldn't be hard at all to do them on the inside). That was really eye openng thing in my building (of mandolins).

 

 

Violin researcher Oliver Rogers and violin maker Pamela Anderson (1) recommended taking the top off the violin repeatedly to rework it in small steps.  To prevent wood damage Pamela used a weak glue-- Elmer's Glue Stick which is water soluble.  Hide glue was used for the final gluing.

Others have used hide glue for all the steps but they used a layer of kraft paper on the spruce plate to prevent wood tear-out when they removed the top plate.  Very weak hide glue has also been used to make removal easier.

I suppose instead they could have removed the back plate and then reworked the top plate from the inside like you mentioned.  The idea of using a dummy rim and neck looks like a practical method.

 

1. Journal of the Violin Society of America, Volume XVIII, No.1,  "From Acoustics Lab to Violin:Engineering and Violin-Making Perspectives" 

[Marty Kasprzyk]

2 hours ago, Torbjörn Zethelius said:

Anyone familiar with the replication crisis? 

The Bilbao violin researchers and makers were concerned with replication so when they made their five different violin combinations of top and back plates (pliable, medium, resistive) they duplicated one of the combinations (medium top with a medium back) which did show the results were closely reproducible in physical, acoustic, player, and listener tests. 

I hope other violin makers don't have reproducing problems.

[Paul McClean]

On 1/16/2021 at 12:39 PM, Paul McClean said:

Thank you David.  I have been enjoying your videos and they have helped me tremendously!!  I don't have a humidity meter to measure the wood but the air humidity is 61.  The spruce I am using was bought in 2011 and it was 3-5 years old when I bought it.  It has been stored in a cool dry place since then if that helps.  I'll thin the centre down to 2.5mm to match the upper and lower bouts,  leaving it at 2.8 around the f holes.  The f hole fluting is already done.  I'll then proceed to fit the bass bar under slight tension and post an update on the weight and modes.

The bass bar is now fitted and measures 13mm high at the highest point.  

Weight 84g

Thickness is 2.5mm all over except for f holes where it is 2.8mm, soundpost area 3.1mm and edges 3.0mm.

Mode 1   76hz

Mode 2   154hz

Mode 5   341hz

Any thoughts on graduating further to reduce the weight?  What would be a reasonable thickness to target for wood of this density without going too far?  Target for tap tones?