• Announcements

    • ghunt

      Forum Update *UPDATED*   12/30/16

      If you are a Maestronet member, you will likely have noticed a major upgrade to our forum software. This new software improves on a number of areas - one of the biggest is mobile support. This new format is responsive, and so will work nicely on browsers of all sizes. Other improvements will be forthcoming shortly, including SSL for the entire site. A few notes that will help you with the new setup: Your username for logging in is now either your screen name, or your email address - either will work. Your old username will no longer work. When typing a message, the system will periodically auto-save your content as you type. If you lose connection, or return at another time, simply to back to the conversation or thread, hit the Reply button, and your saved content will be there ready for editing. There is a link at the top right of every page labelled "Unread Content" which will show you in a nice timeline view new content. The site can send notifications to your browser, but this can be turned off. Have a look around and check out some of the new features. If you notice anything off, post in News, or PM Jeff or Glenn and we will look into it. Happy New Year from the Maestronet Team.
Sign in to follow this  
Followers 0
Jonathan M.

Plate Tuning using mode 5 and 2

26 posts in this topic

I am currently working on finishing my violin plates. I have made progress, however I am confused about the tap tone frequencies of mode 5 and mode 2.

Platetuning.org says the back should be 345 Hz for mode 5 and 171 Hz for mode 2. It also says the belly should be 328 Hz for mode 5 and 172 Hz for mode 2.

On the other hand, The Art of Violin Making by CJ and RC suggests 360 Hz for Mode 5 and 180 Hz for mode 2 for both the back and belly. Which reference should I use? Thanks

Share this post


Link to post
Share on other sites

Hi

Does it matter?

ps - I confess that I wouldn't know a tap-tone from an aubergine.

Share this post


Link to post
Share on other sites
I am currently working on finishing my violin plates. I have made progress, however I am confused about the tap tone frequencies of mode 5 and mode 2.

Platetuning.org says the back should be 345 Hz for mode 5 and 171 Hz for mode 2. It also says the belly should be 328 Hz for mode 5 and 172 Hz for mode 2.

On the other hand, The Art of Violin Making by CJ and RC suggests 360 Hz for Mode 5 and 180 Hz for mode 2 for both the back and belly. Which reference should I use? Thanks

use the force Johnathan!!!

(sorry, couldn't resist it)

Share this post


Link to post
Share on other sites
I am currently working on finishing my violin plates. I have made progress, however I am confused about the tap tone frequencies of mode 5 and mode 2.

Platetuning.org says the back should be 345 Hz for mode 5 and 171 Hz for mode 2. It also says the belly should be 328 Hz for mode 5 and 172 Hz for mode 2.

On the other hand, The Art of Violin Making by CJ and RC suggests 360 Hz for Mode 5 and 180 Hz for mode 2 for both the back and belly. Which reference should I use? Thanks

What does your plates weigh? Weight is likely to be at least as important as tap tones for the backs. The mode 5 in relation to mode 5 in old italians is about 2,3 so none of these references seems to be good on that point. The tops will proably be too thick in the centre if tuned like this.

And what is your preference for sound? And who do you expect to sell the instrument to? A top notch violinist, a decent orchestra musician or an amateur?

Share this post


Link to post
Share on other sites

Collect as many plate tuning combinations as you can find, then calculate the average. You can't go wrong this way!

Oded

Share this post


Link to post
Share on other sites

My violin back currently weighs 120 grams and my belly is 90 grams because it is made out heavy Sitka spruce. I think i may need to remove more material on the plates especially the belly, does anyone have a good plate thickness map that is successful.

Share this post


Link to post
Share on other sites

Ideally, I would be selling the instrument to a top notch violinist. But who wouldnt want to be?

Share this post


Link to post
Share on other sites
What does your plates weigh? Weight is likely to be at least as important as tap tones for the backs. The mode 5 in relation to mode 5 in old italians is about 2,3 so none of these references seems to be good on that point. The tops will proably be too thick in the centre if tuned like this.

And what is your preference for sound? And who do you expect to sell the instrument to? A top notch violinist, a decent orchestra musician or an amateur?

I agree with you, Andres. Stiffness, in other words, may be what is crucial for a back, but I don't have the facts.

Knowing both 2 and 5 would at least be a way to fix some relation of longitudinal to transverse stiffness in a plate... But the top has f-holes and a bassbar. This means that there are other ways to adjust that relationship.

That is why the back interests me more. I am starting to wonder if the shape of the nodal line of the ring mode might be used by itself to adjust the back.

Does anyone have any experience correlating the size and shape of the back nodal line for mode 5 in the back with the relation of modes 2 and 5?

OK..... maybe tap-tuning is out of fashion, but here is something that still seems to me to be a possible use for it.

Share this post


Link to post
Share on other sites
My violin back currently weighs 120 grams and my belly is 90 grams because it is made out heavy Sitka spruce. I think i may need to remove more material on the plates especially the belly, does anyone have a good plate thickness map that is successful.

You may have missed some previous posts. Mass times frequency-squared has the units of a stiffness. Removing a few powers of ten, .8 and 1.2-1.4 work for me for top and back. (mode 5)

Just find the mode frequencies and get your numbers. Pitches of F and F# for top and back work for me. That does not say anything about graduation maps, of course.

Share this post


Link to post
Share on other sites
Jon,

Download the two Strad articles by Joseph Curtin, "Tap-tones" and "Scent of a Violin."

http://www.thestrad.com/hdownloads.asp

You should also subscribe to The Strad.

Mike

I tried several times a dozen years ago. I gave up, they did not seem to read their mail. (paper mail) If the editor sends me an email, I will subscribe. She seems to read the forum.

jmluthier@sbcglobal.net.

I think Mr. Curtin did the right thing to find out about mass. By the way, the stiffness of some of these Chinese tops is quite high. Many are stiffer than ANY top wood I have obtained from violin suppliers. They are as stiff as some Sitka I have used, but less dense.

I think maybe the suppliers had stock that had been picked through. At least such wood exists, but it may be grown in different conditions than most European wood and also may not be the same species. Most likely to me is that the Chinese are going into virgin timber growth.

Share this post


Link to post
Share on other sites

I used the Harris numbers to try to figure out how stiff to go. I haven't handled an old Cremonese violin plate (or any but mine) so I have no idea. I ended up going quite a bit thinner. Seemed way too stiff. The tap tones didn't change that much, but with the lower weight the stiffness number dropped quite a bit. But it seems that other harmonics are added that weren't there when it was thicker. The tap tones are meaningless when the belly is attached to the ribs. All the peaks on the FFT of the free plate are on the troughs of the FFT with the ribs attached. I really don't know much about tap tuning, I just measured it. One graph is the free plate and the other is with the ribs.

post-23466-1248477263_thumb.jpg

post-23466-1248477287_thumb.jpg

Share this post


Link to post
Share on other sites
I used the Harris numbers to try to figure out how stiff to go. I haven't handled an old Cremonese violin plate (or any but mine) so I have no idea. I ended up going quite a bit thinner. Seemed way too stiff. The tap tones didn't change that much, but with the lower weight the stiffness number dropped quite a bit. But it seems that other harmonics are added that weren't there when it was thicker. The tap tones are meaningless when the belly is attached to the ribs. All the peaks on the FFT of the free plate are on the troughs of the FFT with the ribs attached. I really don't know much about tap tuning, I just measured it. One graph is the free plate and the other is with the ribs.

edit (to hell with it)

Share this post


Link to post
Share on other sites
... .

I think Mr. Curtin did the right thing to find out about mass. By the way, the stiffness of some of these Chinese tops is quite high. Many are stiffer than ANY top wood I have obtained from violin suppliers. They are as stiff as some Sitka I have used, but less dense.

I think maybe the suppliers had stock that had been picked through. At least such wood exists, but it may be grown in different conditions than most European wood and also may not be the same species. Most likely to me is that the Chinese are going into virgin timber growth.

I wonder what kind of wood they use.

Can we get a sample to an expert?

Mike

Share this post


Link to post
Share on other sites
I wonder what kind of wood they use.

Can we get a sample to an expert?

Mike

It is not quite like red spruce which is also pretty stiff. At least the samples I have seen. But it is milk white and looks just like Norway spruce. I could take a piece out from under a fingerboard, do you know anyone who can tell from that ?

Share this post


Link to post
Share on other sites
edit (to hell with it)

Shame I missed this.

It would be great to have a consistent record of the wealth of your experience on acoustics/plate movements and emulsion varnishes.

Share this post


Link to post
Share on other sites
Shame I missed this.

It would be great to have a consistent record of the wealth of your experience on acoustics/plate movements and emulsion varnishes.

Hope this is not an ironic comment. Actually, I have spent a lot of time with the emulsions. The plate mechanics is something else. Most of what I have mentioned is latter-day FEA modeling and half-assed physics modeling. My own last violin was three or so years ago. I now know that I consistently made inflections too slight and not inboard enough. I think if I change this, I will get more body of sound.

In other words, experiment has paid off for me in my major field of interest; varnishes. Everything I am doing is in a previous thread with the name "emulsion varnish".

The edited bit was a comment about Harris's effective stiffness. I mentioned this long before that paper of his was published. It is a simple extension of the harmonic oscilator equation. Harris adds 25% of mode 2, but the number is much smaller than for mode 5, so the results are very nearly the same.

Share this post


Link to post
Share on other sites
Hope this is not an ironic comment.

Absolutely not. The fact that I may not follow some of the more advanced modelling, for example, does not diminish the interest with which I read you posts.

If there is irony elsewhere, it's based on the notion that 'complex' measurements, equations etc can substitute for a good eye, common sense and good feel.

ps - There is a nice video of Mr S Zyg where I pointed out that folks should ignore the plate and watch his hands move over the plate.

Share this post


Link to post
Share on other sites

I agree with you that including mode 2 is more or less useless.

Oded

Share this post


Link to post
Share on other sites
Absolutely not. The fact that I may not follow some of the more advanced modelling, for example, does not diminish the interest with which I read you posts.

If there is irony elsewhere, it's based on the notion that 'complex' measurements, equations etc can substitute for a good eye, common sense and good feel.

ps - There is a nice video of Mr S Zyg where I pointed out that folks should ignore the plate and watch his hands move over the plate.

Thanks, I was made suspicious by your exageration of my experience. I really do think that nearly all of it will turn out to be related to perhaps a small number of ideas. That (again) assumes consistent workmanlike construction.

I also agree that there is no point to try to find significance in a lot of data that cannot be controlled (as adjusting a lot of modes.) On the other hand, I still believe that an entire modal analysis describes all of it, for a non-driven system at least. When one first is told that a complete fourier transform describes a wave form, it is hard to swallow. But there is the theorem, proven. Just that one cannot construct the waveform in a practical way with a finite number of tone generators. (Even for a periodic wave)

PS. I used the word "complex" in the specific sense of a number with a real and imaginary part. The equations are set up for the possibility of complex answers. Instead of sines and cosines, one has exp(x + iy) or other things that have time invovlved. ("i" being the square root of -1)

PPS: Not to distract from Sam's abilities, but: If he had started as Vuillaume making pure red violins, where would have his career have gone ??

Share this post


Link to post
Share on other sites
You may have missed some previous posts. Mass times frequency-squared has the units of a stiffness. Removing a few powers of ten, .8 and 1.2-1.4 work for me for top and back. (mode 5)

Just find the mode frequencies and get your numbers. Pitches of F and F# for top and back work for me. That does not say anything about graduation maps, of course.

John,

I am currently finishing two violin backs. The data are as follows:

Mode 5 Mode 2 Weight (grams) m*f^2

380 175 104 1.51

368 162 108 1.46

The upper bouts are about 2.3mm

Middle bouts about 4.5mm max

Lower bouts 2.4mm

To meet your criteria of 1.2-1.4, the plates should be thinned more. However, I am afraid of getting them too thin. Any advice for me?

David Burgess: Your advice would be appreciated as well.

Thanks

Share this post


Link to post
Share on other sites
John,

I am currently finishing two violin backs. The data are as follows:

Mode 5 Mode 2 Weight (grams) m*f^2

380 175 104 1.51

368 162 108 1.46

The upper bouts are about 2.3mm

Middle bouts about 4.5mm max

Lower bouts 2.4mm

To meet your criteria of 1.2-1.4, the plates should be thinned more. However, I am afraid of getting them too thin. Any advice for me?

David Burgess: Your advice would be appreciated as well.

Thanks

There was no hard rule other than that I did not want a too-weak back. I would say that these are so close you likely could not tell the difference. They are also not heavy. Wood I have used in the past may have been more dense and also I may not have thinned as much in the lungs.

I think you should leave them. My new ideas are thinner lungs anyway. I appreciate knowing your numbers.

You are close to F# which I take to be about 170 Hz. F is nice for a top complete with bar, if it come in around 70 grams, plus or minus a few. Others may differ because some like to get into the low 60's for a top. A little extra wood might be appreciated. You can take them apart later and thin.

What are your top numbers? Personally, I will admit that I do not split hairs on the formula thing. I take a pitch and a mass which both seem right. It is rather rough, not "scientific."

Share this post


Link to post
Share on other sites
What are your top numbers?

John,

The tops have not had the f-holes cut yet. They are light and stiff. Still about 3.5 mm. I don't think I shall any problem with the tops, but I will let you know how they turn out.

Thanks

Share this post


Link to post
Share on other sites
John,

The tops have not had the f-holes cut yet. They are light and stiff. Still about 3.5 mm. I don't think I shall any problem with the tops, but I will let you know how they turn out.

Thanks

I found that it was very useful to at least find a mode 5 and mass at this point.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Recently Browsing   0 members

    No registered users viewing this page.