plate tuning and the old bass bar

[tarisio]

Hello,

I am wondering to what pitch the old masters tuned their plates. I can read in several books that their bellies and backs are both tuned to f.

But there are questions remaining: To what extent does the old bass bar distort this equilibrium. Was there a big difference in the plate's pitches when 19th century makers took out the old short bass bars and put in the stronger ones?

I assume it could not be more than a 1/4 tone. What do you think?

What about the sealer and varnish. Does it alter the pitch significantly?

Does anybody have experiences in this?

Regards,

tarisio

[MANFIO]

I tuned some of my violins and viola plates, and I abandoned the idea after making some instruments that sounded not all that good.

I prefer using my intuition today. I like also to test the resistance of the plates against the pressure of my thumb. I try to avoid hollow sonority of the plates when knocked a bit heavily (Zukerman told me to do this way, he knocks heavly the instrument to see if it's healthy, and told me to avoid places with a hollow sonority due to overthining).

Other factors influence the sound. For instance, you can leave your plates thicker (thus giving a higher note) if you adopt higher ribs and a wide model, as in the case of Del Gesùs Cannon model.

I don't tune the top with the bass bar too, but I do look for a clear, free tone, without looking for a given note.

[Oded Kishony]

There are three reasons why you should not pay attention to free plate tuning: The Italians probably didn't do it, The pitch of the plate (with or without the bar) changes over time (goes up as the wood gets stiffer with age) and most old violins have been tinkered with anyway and therefore don't reveal theintention of the maker.

Tap tones CAN be useful if you combine the pitch along with the weight of the plate. The two major factors in wood that control sound are density and stiffness; tap tones will tell you about stiffness and the weight will give you a clue about density. I like to determine the density of my wood before I start carving. This way I know approximately what to expect the weight of my finished plate to end up. To determine the dnsity of wood you simply float it in water (end to end) and measure how far it sinks, the ratio of floating to sinking is your density. Typically good tonewood spruce has a density of around 4.0 or less.

Oded Kishony

[bob kogut]

May I add a thought to Oded's excellent summary of density and stiffness affecting tap tones:

I believe that the arching pattern of the plate has a tremendous effect on the stiffness of that plate, thus affecting the tap tone. Maybe that would explain the frequent failure of regraduation attempts which only change the thickness(relative density),but not the stiffness as much ?

[Regis]

If I understand this correctly, density tells you how thin the plates need to be (using one's preferred graduation pattern). Stiffness can be identified but, you can do nothing significant to improve it.

Am I reading this right?

Regis

[Michael Darnton]

If the implication is that somehow tuning (or graduation) can compensate for arching, I completely disagree.

[bob kogut]

Michael,

My implication was actually that regraduation cannot compensate for arching.

I guess my wording was unclear.

[tarisio]

Thank you all for participating so far.

Manfio and Oded Kishony:

I agree. Plates glued to the sides do NOT behave like they do in their free state.

I only think of tuning them to a certain pitch to get a hint on when thinning is finished.

In short: Tuning for static reasons.

Ok, there are other variables, f. e. the arching I cannot cover with this.

But there is evidence that the old masters tuned their plates:

Sacconi told us about f/fis in Strad plates.

Maybe you do not know "Otto Moeckel - Die Kunst des Geigenbaus, 1st editiion 1930"

Moeckel was a well-reputated Berlin luthier around a hundred years ago. He was able to measure the pitch of old Cremonese plates and published them in his 1st edition. He too was *not* in favour of tuning plates for tonal reasons. Here is some data:

__________| belly |back | difference

Strad 1701 | e | e 1/4 | 0.25 tones

Strad 1708 | f | e 1/4 | 0.25

Strad 1709 | fis 1/4 | g | 0.25

Strad 1712 | g 1/4 | g | 0.25

Strad 1720 | fis | fis | 0.0

Strad 1726 | e | fis | 1.0

Most striking are the little differences of belly and back tunes.

So I come to the conclusion that Stradivari tuned the plates. I do not say that this was necessary but it seems to have been a common practise.

My question is: To what pitch should a belly be tuned in the white without ff and without bass bar to get the desired tone f in varnished state?

Example:__________________pitch

belly white_________________?

belly white with ff __________?

belly white with ff and bar____?

belly sealed and varnished____f

Is there a pitch difference between old and new bass bar?

[Michael Darnton]

If anything, the scattered nature of the evidence you show demonstrates that plates weren't tuned.

Properly made violin plates do fall within a range, however you shouldn't confuse cause and effect. My plates are always around the same note, and once I had a visitor pick one up and say that it appeared to be perfectly tuned according to his standards, but I've never tuned a plate in my life. I do, however, follow good violin making standards and am reasonably consistent.

[MANFIO]

I've dicovered also, that my instruments, when assembled and stringed, gives the same note when knocked in different places, even when I compare very good ones with "not all that good" ones.

[tarisio]

Quote:

---

My plates are always around the same note

---

Would you mind telling us around which note w/o ff and bar?

[Michael Darnton]

Usually around D or Eb without, E or F with. I've never had one ring F#, in spite of everything I've read about that, though by backs are usually near F#.

[David Tseng]

I don't tune my plates either. The tap tones for tops are usually D most of the time, with bassbar, E to F. With the plate thickness in the range of 2 to 2.3mm, it will not go up to F#. Backs are more often F, sometimes F#.

[La Folia]

It appears to me that although the tap tones of the Strads vary by up to a third, the top and the back are within 1/4 tone with only one exception. That sure suggests tuning to me.

Don't ask me how bass bars, tinkering, and age may have affected it. Still, the data do suggest a remarkable consistency within each instrument, do they not?

[Michael Darnton]

But notice how mine and David's backs are also consistent, though we don't tune.

[MANFIO]

Michael, I supose that some thick plated Del Gesùs (as the Cannon) gives a higher note that is counterbalanced by the high ribs and the wide model.

[tarisio]

Manfio,

you mention del Gesu. Here is some data among others taken from the same book. Unfortunately Moeckel did not mention the years except for the Strads:

___________________|belly|back|difference

Gasparo da Salo _____|f |f#1/4| 0.25 tones

Nicolo Amati ________ |d# |f | 1.0

Nicolo Amati ________|f# |e | 1.0

F.Rugeri d.i. Per _____|e |g# | 2.0

Carlo Bergonzi _______|e |d# | 0.5

G. del Gesu _________|f1/4 |g | 0.75

Compared to Stradivari we see there is more bandwidth between the tones of belly and back in average.

If they tuned or not this shows once again how consistent Stradivari worked. Or the others followed a different intention.

It would be interesting to see more tuning data of del Gesu, Bergonzi, da Salo etc.

But that's all the book provides concerning Brescian and Cremonese workshops.

[MANFIO]

Thank you, but the lack of identification of the violin makes the study useless because we don't know if the instrument was regraduated, as ocurred with most Del Gesùs. I was interested in information about well preserved Del Gesùs, such as the Cannon.

[Oded Kishony]

There's plenty of data for you to choose from as far as a range of tap tones-you can also check Harry Wake and Catgut Acoustical Journal for additional information about tap tones. Here's something for youto try: Tap your plate >as< you are carving it and notice the effect of the arching on your tap tone-you may discover something interesting in the process. As with everything in violinmaking you >must< put every bit of information into context. Carleen Hutchins at one time focused entirely on obtaining certain tap tone frequencies but would end up with very thick heavy plates at the desired tap tone-well these instruments sounded terrible-you must look at everything! Perhaps you should try to find out what effects your ground/varnish has on the final stiffness of your plates before you commit to a particular pitch (?) How much dampening does your ground/varnish cause? There are loads of questions that you should be thinking about besides tap tone frequencies.

Oded Kishony

[David Tseng]

I started making violins by associating myself with that Catgut group. I mastered the

Chladni method and was able to see the pitfalls of it and finally abandoned this erroneous

approach. All in all, I wasted several years of my life doing that stupid thing.

"That woman" insisted that mode 2 and 5 should be tuned to F# for both top and back. She

cited that a Strad she tested was tuned that way. I've never seen the data published. It

was tested in her early years before she even learned Chladni's 19th Century physics. She

did publish the results of another concert Strad: mode 5 for back was 340 Hz (between E

and F, E=329.6, F=349.2Hz) and for top, 315 Hz (close to D#). Under the boundary condition

she used: rubber band at 4 corners, the mode 2 would not be excited (at least not

strongly). She discarded this result and selectively chose the other one to promote her

F# theory.

The trouble with Chladni method is it is a free plate vibration mode and therefore

sensitive to the boundary condition, once the plate is attached to the rib, the mode

disappears. OK, one can try to establish an empirical relationship between the free-

plate modes and the tone of a completed violin. The problem is people only tune one

or two low frequency modes such as 5 and 2. These low freq. modes involve large area of

the plate, one can remove wood at some area without affecting the mode freq. No one knows

how to handle the high freq modes. I don't believe they would tune the plate in 18th C.

Cremona.

[Oded Kishony]

You're quite right David. One of the most interesting researchers working today, Martin Schleske systematically proved (CAS journal) that there is no correlation between free plate frequency and the modal frequencies of the assembled instrument. I don't think this discussion is over yet, there's too much we don't know about how a violin works. I've heard some interesting ideas about the role of Mode 2 as it relates to the finished instrument. A long time ago Simon Sacconi speculated that the Cremonese may have tuned the instrument in the white.

Oded Kishony

[MANFIO]

Yes Oded, I think the ground and varnish can have an importance, I use a soft ground and varnish with my somewhat thick plates.

[llama]

I'm very much in favour of this view.

You can get a clear understanding of how indeterminate the system is by using a teacup and saucer... tap the saucer as a free plate and listen to not just the tap tone, but the harmonics as well... then put the saucer on top of the teacup and hear the difference

When I first got into the whole violin acoustics thing, I was excited at the volume of data available in the CAS journal, and then as I read it I became dissapointed by it. Free plate modes do not have anything to do with the response of the finished instrument, at least not in any meaningful determinate way. There are only a handful of CAS articles which deal with this issue, and I think the recent direction of the journal reflects this thinking which is encouraging.

The tap tone is an effect, not a cause... it's like saying the equations 10+15=25 and 9+16=25 are the same because they have the same result. One however is the sum of two squares, while the other is not. The tap tone really only tells you how much of a plate you have, not anything about the quality of the plate. The difference in tone produced by a different cut of the bridge, in combination with a the comlete system which reacts to whatever is filtered through the bridge is a universe away from a single mode.

This is why the majority of Schleske's experiments are done on assembled instruments (except for those which seek to demonstrate why they should be done that way), and his point source for the impulse is at the point where the strings meet the bridge!!

...

Modern acoustics is performed in a subtractive manner, where the acoustic designer attempts to create a system sympathetic to all frequencies by seeking to eliminate resonances, not re-inforcing them.

By contrast, ancient acoustics was more an additive process - Vitruvius describes a passive amplification process in the theatre by using jars tuned to each note of the greek scale (which features a lot of 1/4 tones if memory serves).

Either way, the idea is to create a balance across a single octave and then also across the whole spectrum. If old makers tuned their plates, we would never have been able to change the frequency of concert A.

One could argue the best tap tone theoretically is no tap tone at all, but a 'crack'.

[MANFIO]

That's why I prefer just tuning my violin "e", "a", "d" and "g"!

[DarylG]

LOL, good one Manfio!