H.R.Fisher

plate tuning specs ?

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    I am currently in the process of trying to learn plate tuning using the chladni method. Listed below are the current specs of my first attempt.  Will this work?

Your input will be greatly appreciated.   Thanks,   Henry

     Top plate wt. w/  BB and ff     71gr

      Back plate                                  122gr

      Tap tone both top and back       F

      Mode  1    Top    99hz

                         back  118hz

      Mode 2       Top    168 hz

                          Back   168 hz

      Mode 5        Top     370 hz

                           Back    342  hz 

             

 

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1 hour ago, H.R.Fisher said:

    Will this work?

I see nothing outrageous in the specs that would prevent it from working.

However, in my opinion, the things that determine how well it works are not written in this kind of plate data, although there could be some vague clues.  It looks a bit heavier and stiffer than what I normally do, but what I do might not be all that normal.  I tend to specifically  look for good stiffness/weight wood, and go light-ish.  Your back is fairly heavy, with a low M5, indicating the maple might not be terribly stiff along the grain (highly figured?  high density?).  As for how this might affect the performance, I couldn't say.  Put it together and see what happens.

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The top mode 5 is maybe a little high still at 370? And shouldn't the top mode 5 also be lower than the back mode 5? (questions for Don :))

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3 hours ago, Emilg said:

The top mode 5 is maybe a little high still at 370? And shouldn't the top mode 5 also be lower than the back mode 5? (questions for Don :))

I won't say what any of these modes "should" be, just what I observe from my experience, with the caveat that I tend to go light and thin.  So, yes, the top weight and taptone are higher than what I do, and the back is heavier and with a lower M5 than I get.  And the back M5 usually is higher than the top... but a few of mine had very low back M5, much lower than the top, and they worked.

I don't put much stock in Chladni patterns or formulas, mostly just go by weight, and go a bit heavier if the stiffness is looking low, and a bit lighter if the stiffness is looking high.  No real goal, other than 60g or less for the bare top (no bar) and ~100g for the back (less fussy about the back weight).  Dense wood won't want to be that light.

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16 hours ago, H.R.Fisher said:

    I am currently in the process of trying to learn plate tuning using the chladni method. Listed below are the current specs of my first attempt.  Will this work?

Your input will be greatly appreciated.   Thanks,   Henry

     Top plate wt. w/  BB and ff     71gr

      Back plate                                  122gr

      Tap tone both top and back       F

      Mode  1    Top    99hz

                         back  118hz

      Mode 2       Top    168 hz

                          Back   168 hz

      Mode 5        Top     370 hz

                           Back    342  hz 

             

 

I'm curious to know why you indicate a single tap tone note and then make a list of modes.

Tap tone notes correspond to the modes frequencies, so you should hear a F for the M2 and M5 of the back, and a F# for the top M5 and Fa for the top M2.

I agree with Don, nothing strange with your modes, the back a bit heavy that at that frequency says maybe a bit soft or a bit dense wood.

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Thanks Don. Sofar i'm just measuring weight and M5 only.. for us beginners it gives something to start with.

Seeing modes, weights, densities all over the place - also from Strads and del Gesus - i'm guessing there is not much magical about the numbers per se, so i agree.

One thing is puzzling me a bit: on my latest 2 tops (made 4 sofar, good euro spuce, densities 0.39/0.40) i havent been able to get the weight with BB below 70g as M5 was getting too low at 330/335. For the first 2 violins i stuck to M5=350, resulting in 80g and 75g.

Is the wood too dense or could it be the arching?

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To add a bit of confusion :unsure:I can say that in my violins the M5 of the top is normally higher than the back, sometimes equal, rarely lower (but this happened too).

Needless to say, they all sounded great for a musician or another (not everyone always agreed....^_^)

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13 minutes ago, Davide Sora said:
 
 
I'm curious to know why you indicate a single tap tone note and then make a list of modes.

Tap tone notes correspond to the modes frequencies, so you should hear a F for the M2 and M5 of the back, and a F# for the top M5 and Fa for the top M2.

I agree with Don, nothing strange with your modes, the back a bit heavy that at that frequency says maybe a bit soft or a bit dense wood.

yes David,  I listed the tap tones by tapping the plates and comparing them with my piano. In my naivete I didn't occur to me until you mentioned it that this is the same as the mode frequencies.  And  yes the back is very dense maple.  thanks, I;m learning   Henry

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45 minutes ago, Emilg said:

One thing is puzzling me a bit: on my latest 2 tops (made 4 sofar, good euro spuce, densities 0.39/0.40) i havent been able to get the weight with BB below 70g as M5 was getting too low at 330/335. For the first 2 violins i stuck to M5=350, resulting in 80g and 75g.

Is the wood too dense or could it be the arching?

The most important data is:  how did the first 4 violins turn out?  Signature modes in acceptable places?  Stiff or compliant under the bow?  Tubby or screechy?

The goal isn't to get the free plates to some level, but get the violin balanced.  If the first ones were stiff and lacking bottom end, then use that information to go thinner next time... or regraduate what you have.

But... the free plate data does give some  information, and if the taptones are low and weight high, yes, dense wood or low arching can cause that.

7 minutes ago, H.R.Fisher said:

    PLEASE! PLEASE !!  spare me!

Spare yourself... don't look. :)

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18 minutes ago, Davide Sora said:
 

In case you are not yet sufficiently confused, this is my scheme to listen to tap tones, with indicated the grip points (presa) and listening points (ascolto).

The critical question is:  what do you DO with that information?  I can't imagine trying to "tune" all those modes to some specific goal, but maybe you are working beyond my imagination.

I use slightly different grip and listen points to measure M1, M2, and M5... and even that doesn't seem to predict much about the result, so I don't bother with any of the other modes.  Theory and experience (mine, anyway) say that the edge conditions change it all in a huge way so that the assembled instrument modes are not all that directly connected to the free plate modes... and the really important aspects of a good violin are mostly in the middle and higher frequencies where these low modes tell you almost nothing.

To sum it up from my viewpoint:  plate weights and taptones can help get into a vague zone of stiffness or compliance of the instrument.  A gazillion other details determine everything else, and there's a lot to "everything else".

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58 minutes ago, Davide Sora said:
 

In case you are not yet sufficiently confused, this is my scheme to listen to tap tones, with indicated the grip points (presa) and listening points (ascolto).

Have fun!!

5a28038e27c8b_schematap-tonesrid.thumb.jpg.fc2dade1b4949e5b7b32b2405390ce3e.jpg

Hi Davide, just to clarify, are "listening points (ascolto)" where you are tapping?  

-Jim

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6 hours ago, Jim Bress said:

Hi Davide, just to clarify, are "listening points (ascolto)" where you are tapping?  

-Jim

Yes, I tap on the rear and put my hear (or the microphone) on the other side to listen and catch the note.

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7 hours ago, Don Noon said:

The critical question is:  what do you DO with that information?  I can't imagine trying to "tune" all those modes to some specific goal, but maybe you are working beyond my imagination.

I use slightly different grip and listen points to measure M1, M2, and M5... and even that doesn't seem to predict much about the result, so I don't bother with any of the other modes.  Theory and experience (mine, anyway) say that the edge conditions change it all in a huge way so that the assembled instrument modes are not all that directly connected to the free plate modes... and the really important aspects of a good violin are mostly in the middle and higher frequencies where these low modes tell you almost nothing.

To sum it up from my viewpoint:  plate weights and taptones can help get into a vague zone of stiffness or compliance of the instrument.  A gazillion other details determine everything else, and there's a lot to "everything else".

 
Don't worry, I have come to your same conclusions, no magic modes tuning system can predict the future.....
 
I started trying to understand what were the notes you hear by tapping the plates when I realized that in the cello for some years I mistakenly exchanged the M3 with the M2 and despite this the instruments worked well, so I began to think about the usefulness of this kind of thing....:rolleyes::)
 
A vaguely useful thing is that if some modes are not heard distinctly, it means that plates are probably still too stiff and you can go on thinning, also useful for bassbar shaping expecially with M6 that I call bassbar mode because you can't hear it without bassbar, tapping and listening by ear only (no Audacity).
M5 and M2 are the best relative stiffness indicator, M1 may give some clue, all others modes are totally out of control and nothing else can be done but listening to them taking notes (need only few seconds, so why not....)
If modes frequencies stay the same might be an indicator that you can go on thinning that area till they start to go down, paying attention to the edges because it is misleading as you say, best to use your common sense for this area, not mode frequencies.

Last but not least, very useful to impress people who will believe you have some magical tuning system, even if you insist on saying it is not true, they will believe that you do not want to reveal your secrets gained through years of experience.....:rolleyes:

Oh, I was forgetting the most important thing, that's fun !!  :P

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I guess much like my blood pressure readings,it tells me what my blood pressure is but not much about my health otherwise. But than again it;s bad if too high and bad if it;s too low. But one must start somewhere.

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18 hours ago, Don Noon said:

The most important data is:  how did the first 4 violins turn out?  Signature modes in acceptable places?  Stiff or compliant under the bow?  Tubby or screechy?

The goal isn't to get the free plates to some level, but get the violin balanced.  If the first ones were stiff and lacking bottom end, then use that information to go thinner next time... or regraduate what you have.

But... the free plate data does give some  information, and if the taptones are low and weight high, yes, dense wood or low arching can cause that.

 

In fact they all sound different, varying from overbuilt (the 80g top) to underbuilt (the 70g top), but i'm still learning what exactly good violin sound is

I haven't paid much attention to signature modes yet, but i will do some reading and measuring B)

 

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Not to discourage any would-be plate tuners, but there have been so many varied schemes claimed by their disciples to be the solution for building a good sounding instrument. Out of all the different schemes though, which is the right one? They can't all be right, or maybe they are all equally wrong.

Interestingly, builders that make a violin based purely on weight, feel, instinct and good construction practices seem to arrive at about the same level of success. There really isn't any magic formula aside from experience and good workmanship.

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There was a man in England who was found tapping railway lines with a hammer.  When asked why he did it he replied that it kept elephants away.

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2 hours ago, Bill Yacey said:

Not to discourage any would-be plate tuners, but there have been so many varied schemes claimed by their disciples to be the solution for building a good sounding instrument. Out of all the different schemes though, which is the right one? They can't all be right, or maybe they are all equally wrong.

Interestingly, builders that make a violin based purely on weight, feel, instinct and good construction practices seem to arrive at about the same level of success. There really isn't any magic formula aside from experience and good workmanship.

I agree, experience and good workmanship, I also think all parts of the violin have to work together, in harmony, like a group of singers, the more they or in harmony with each other the better they sound. getting all the parts on a complete assembled violin in harmony together is the challenge. Those who past the VSA (Violin Society of America) surely must know something.

 

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