Marilyn Wallin

[Dean_Lapinel]

Here’s an example of the odd way I think.

I was thinking about something Marilyn Wallin said in one of her posts concerning tension and the rib garland (wish I could find that post again) Marilyn is a really bright thinker.

I would like to see her approach again because she wrote about tension in the violin. I thought about that and still think about that. Now I am really curious. Has anyone studied how much the garland moves when the mold is taken out (no plates) and allowed to settle to a relaxed state?

I suspect this varies with the amount of tension applied to the ribs that were bent. If the ribs were bent perfectly then there would be little to no movement.

Does this matter? If I had a violin with some tension on the garland but preserved that tension by gluing a plate then the second one to a fixed line is that harmful in some way to the violin acoustically, structurally short or long term. Is a violin that has no garland tension better in any way?

Can someone give a yell to Marilyn Wallin so she sees this post (she changes her screen name so I never know where she is)?

I wish she would post more often. Marilyn is probably a great teacher...she hits that "out of the box" button that stays with you.

[Bill Yacey]

My theory is that any tensions built into the instrument cause it to want to continually change to another shape to relieve the tension. Of course, we don't want that to happen, so to my way of thinking, no tension is best.

I'm not convinced springing the bar creates enough opposite tension to counteract the bridge pressures on the belly either. If the bar is strong enough, I can't see the point of springing the bar.

It will be interesting to see other opinions on this.

[Dean_Lapinel]

My theory is that any tensions built into the instrument cause it to want to continually change to another shape to relieve the tension. Of course, we don't want that to happen, so to my way of thinking, no tension is best.

I'm not convinced springing the bar creates enough opposite tension to counteract the bridge pressures on the belly either. If the bar is strong enough, I can't see the point of springing the bar.

It will be interesting to see other opinions on this.

I would have to change my approach since my ribs are not tension free when I glue them. I could do this with forms that account for rebound but that is more work since I don't make the same model violin all the time.

[Torbjörn Zethelius]

Tension built in to the violin could possibly counteract the pull from the strings. I don't think that some built in tension is harmful as long as the instrument is structurally sound. I can't imagine that Del Gesù cared too much about it either, and his instruments works just fine.

[Dean_Lapinel]

Tension built in to the violin could possibly counteract the pull from the strings. I don't think that some built in tension is harmful as long as the instrument is structurally sound. I can't imagine that Del Gesù cared too much about it either, and his instruments works just fine.

True. Makes my thread a little embarrassing when you put it that way. I guess I'm more curious about the hypothetical aspect.

[MANFIO]

I think that most of the tension (when present) will disappear under dry/humid cycles during varnishig. When the wood is wetted it settles in a different way after drying, releasing the tension. But I may be wrong, and I am not saying that I like tension on my instruments.

[NewNewbie]

If you have the VSA journals you might find the following article helpful.

VSA Journal

Proceedings of the 21st Convention

1994

13 #3

"Internal Tension in Violins, Violas, and Cellos" page 59

By: Peter Paul Prier

This link may or may not work as it is WayBack Machine, since the web-page for Prierviolins.com does not contain this article anymore.

[Roger Hill]

If you have the VSA journals you might find the following article helpful.

VSA Journal

Proceedings of the 21st Convention

1994

13 #3

"Internal Tension in Violins, Violas, and Cellos" page 59

By: Peter Paul Prier

This link may or may not work as it is WayBack Machine, since the web-page for Prierviolins.com does not contain this article anymore.

the article is here: http://web.archive.org/web/20040902121230/...onInViolins.htm

[Michael_Molnar]

Where is John Masters on this thread?

Staying tuned.

[Dean_Lapinel]

Where is John Masters on this thread?

Staying tuned.

Stay tuned for sure. It's possible that the man himself might make a comment (Peter Prier). I hope-

[David Burgess]

Marilyn is President of the VSA now, so that's probably taking a lot of the time that she once used for posting.

[Craig Tucker]

For what it's worth - and that's not much, my opinion is that tension in the ribs is not likely to effect the final performance of the violin much, if at all.

Further, tension in them specifically may well just be as liable to improve as detract from the final performance of the violin - just as sprung bass bars remain a point of contention amongst violin makers; you can believe what you believe, but I don't think that there is any evidence to prove the point either way, in any case...

For one thing, if the ribs are bent close to the form, but are sprung just a bit to the final shape (which I believe would be the most common practice amongst makers), and then, the linings are glued on in order to reinforce the correct final shape of the free rib assembly, which the linings do seem to accomplish, as if it was now a sort of ply - then, with the linings glued to the ribs, and the ribs to the plates, the resulting deformation or even the static forces resulting from the slight spring, will realistically be about nil...

But - I have heard the theory that building in such tension will increase the dynamic response, and I have also heard the opposite theory - that building ribs with no tension will result in a better violin somehow.

I don't really buy either scenario - I believe that the results are dependant on other factors than tension in the bass bar, the rib assembly, or even the tension that results from the 1 to 2 mm taper of the rib assembly from the upper corners towards the neck block.

I have made them both ways with (with and without the taper) equal tonal success.

Also, both dry or even cold bending (which methods I have tried) will result in a correctly bent rib assembly, depending on the technique used and length of time in the jig... These ribs act pretty much just like traditional heat bent ribs.

[Wm. Johnston]

For what it's worth - and that's not much, my opinion is that tension in the ribs is not likely to effect the final performance of the violin much, if at all.

I tinkered with the rib heights on my most recent violin. When the ribs were greater than 32.5mm tall (possibly it was 32mm I'd have to look at my notes to be sure) the violin didn't seem as responsive as it was with lower ribs. Once the rib height got below 32mm, further thinning caused little effect. I didn't go below 30mm for the rib hieght so I don't know if there was a point at which rib height would start causing changes again. Thinning the linings didn't seem to do much either. Since the rib height and lining stiffness did little to the violin I don't think that something like a little tension in the ribs would do a lot either.

[grajki]

I don't really buy either scenario - I believe that the results are dependant on other factors than tension in the bass bar, the rib assembly, or even the tension that results from the 1 to 2 mm taper of the rib assembly towards the neck block.

I have made them both ways with (with and without the taper) equal tonal success.

I'd always been under the impression that tension in the system is to be avoided, eg. care is to be taken that the plates are flat and free from twisting.

Then along comes the measurements and we see that the ribs taper 1 to 2 mm down from the shoulders to the neck so not only is tension is being introduced here but so also is an apparent contradiction.

R (confused of Scotland)

[Craig Tucker]

I'd always been under the impression that tension in the system is to be avoided, eg. care is to be taken that the plates are flat and free from twisting.

Then along comes the measurements and we see that the ribs taper 1 to 2 mm down from the shoulders to the neck so not only is tension is being introduced here but so also is an apparent contradiction.

R (confused of Scotland)

Then, you'll have fun with this one.

There is a theory out there that this is the reason for springing the bass bar.

The bar is sprung about as much as the ribs taper, and when the plate has been tensioned (bent) to fit the taper from the upper corners to the top block, the tension in the bar is equalized - almost as if it hadn't been sprung...

It's not my theory, but I have heard it said that this is the reason for the spring in the bar. It seems almost logical on the surface - since I don't spring the bar I haven't thought much about it - I admit.

[Don Noon]

It seems to me that any built-in stresses will pale in comparison to the stresses put on by the strings. However, as a matter of principle, I try not to build in any additional stress. However (lots of howevers), I think built-in stresses are unavoidable to some degree. When you bend a piece of wood, there are internal stresses locked in. Try bending a rib, and set it aside for a few weeks. Does it maintain its shape, or change? Mine seem to change overnight. Then, when you glue linings (or anything, for that matter) with hide glue, you're putting hot water on wood... surface expansion, then contraction as it dries, and the glue contracts. More localized stresses. Varnish shrinks, too. Now, for the last "however": to the best of my knowledge, these internal stresses will only affect the acoustics (dynamic stress effects) for a few weeks or so.

[grajki]

Then, you'll have fun with this one.

There is a theory out there that this is the reason for springing the bass bar.

The bar is sprung about as much as the ribs taper, and when the plate has been tensioned (bent) to fit the taper from the upper corners to the top block, the tension in the bar is equalized - almost as if it hadn't been sprung...

It's not my theory, but I have heard it said that this is the reason for the spring in the bar. It seems almost logical on the surface - since I don't spring the bar I haven't thought much about it - I admit.

Ha!

tension conservation to be zero all round...

Not convinced!

Ain't the bass bar tensioned at both ends when it is? So if that's the case, where is the 1 to 2 mm reduction in rib height from the hip corners to the bottom?

Not dissrespecting your reply CT, just looking for consistency.

[grajki]

Besides, if you're springing the bass bar down at the top end (middle of the ffs to the neck) then surely the plate is being tensioned BEFORE being more tensioned by getting glued to negative slope...double stress!

[Craig Tucker]

Not convinced!

Ain't the bass bar tensioned at both ends when it is? So if that's the case, where is the 1 to 2 mm reduction in rib height from the hip corners to the bottom?

Not dissrespecting your reply CT, just looking for consistency.

Well, I can't say I'm convinced either - but I've heard this idea bandied about

Plus, the fact that you responded the way you did, is (in my opinion) a sign of respect. Plus, I'm definitely not fishing for polite agreement, but more and better ideas.

As I mentioned though, it's not my idea, and I haven't bothered "doing the math" so to speak, I'm merely repeating what I've heard. Since I don't spring the bar, it doesn't really effect me.

[joerobson]

Hi Dean,

"Marilyn is a really bright thinker"...you're right on with that. Doing the varnish workshop project with her has been a real pleasure! She is kind of "off the grid" for a week or so, but I'll let her know to respond when she can.

on we go,

Joe

[Johnmasters]

Here’s an example of the odd way I think.

I was thinking about something Marilyn Wallin said in one of her posts concerning tension and the rib garland (wish I could find that post again) Marilyn is a really bright thinker.

I would like to see her approach again because she wrote about tension in the violin. I thought about that and still think about that. Now I am really curious. Has anyone studied how much the garland moves when the mold is taken out (no plates) and allowed to settle to a relaxed state?

I suspect this varies with the amount of tension applied to the ribs that were bent. If the ribs were bent perfectly then there would be little to no movement.

Does this matter? If I had a violin with some tension on the garland but preserved that tension by gluing a plate then the second one to a fixed line is that harmful in some way to the violin acoustically, structurally short or long term. Is a violin that has no garland tension better in any way?

Can someone give a yell to Marilyn Wallin so she sees this post (she changes her screen name so I never know where she is)?

The ribs are cylindrical (they have no curvature. They can distort by bending with no in-plane forces) What I would like to know about is stresses in the curved shells. This seems to affect tone, but nobody seems to be able to explain why. (And I have asked big boys) That is a major problem.

I wish she would post more often. Marilyn is probably a great teacher...she hits that "out of the box" button that stays with you.

The ribs are cylindrical, they have no Gausian curvature. They can move by bending only, with no in-plane stretching. What I want to know is how tension in the curved plates, shells, affects tone, and why. Nobody seems to know. (And I have asked the big boy) To answer your question, I have found that initial stresses in the ribs, from bending etc to fit plates, has no lasting effect.

I have mentioned this in the past and pointed out that "stress" has a negative connotation; we do not feel well when we have stress. Therefore it seems "natural" that a violin should not have unequilibrated stresses. But that is not a logical intuition, as I am sure you agree. If Marylin can answer me, I would love to hear it.

True. Makes my thread a little embarrassing when you put it that way. I guess I'm more curious about the hypothetical aspect.

Don't feel embarrassed. It is a very difficult question. There will be an eventual state from creep that minimizes the potential energy represented by stress, but the question still remains about the extra forces. (other than those countering neck and string forces)

I don't think it has been answered at all. I have heard that it causes a geometrical change which explains things. But that has to be false. Such small changes are well within working tolerances and very negligible.

If you have the VSA journals you might find the following article helpful.

VSA Journal

Proceedings of the 21st Convention

1994

13 #3

"Internal Tension in Violins, Violas, and Cellos" page 59

By: Peter Paul Prier

This link may or may not work as it is WayBack Machine, since the web-page for Prierviolins.com does not contain this article anymore.

I read this. It says nothing about tonal effects. It just assumes the original question. No maker can address this from a technical standpoint. The answer does not seem to be found yet.

Where is John Masters on this thread?

Staying tuned.

Howdy Mike. I fear that I may be dismissed, espescially after you read the above. But really, You-know-who says he does not have a good answer. I hope he does not mind my saying this. Likely it is a big problem with not much interest at the time. My guess would have one looking microscopically at wood structure and how it might be affected. That is a very weak guess. I really have no ideas.

Stay tuned for sure. It's possible that the man himself might make a comment (Peter Prier). I hope-

He does not know either. I volunteer this on my own. How could he? A top-notch theoretician who is interested in musical acoustics does not have a clear answer. (This person may have a lot of ideas, or none at all. He did not say.)

[Johnmasters]

It seems to me that any built-in stresses will pale in comparison to the stresses put on by the strings. However, as a matter of principle, I try not to build in any additional stress. However (lots of howevers), I think built-in stresses are unavoidable to some degree. When you bend a piece of wood, there are internal stresses locked in. Try bending a rib, and set it aside for a few weeks. Does it maintain its shape, or change? Mine seem to change overnight. Then, when you glue linings (or anything, for that matter) with hide glue, you're putting hot water on wood... surface expansion, then contraction as it dries, and the glue contracts. More localized stresses. Varnish shrinks, too. Now, for the last "however": to the best of my knowledge, these internal stresses will only affect the acoustics (dynamic stress effects) for a few weeks or so.

The shape of the arch will determine how these stresses are distributed. Michael Darnton is right, in my opinion. Graduations are less important than archings. I am hard at work making new FEA models. At this point, I have an idea for an optimum longitudinal arch. (the transverse arches are CC referenced to the longitudinal one.) The idea is to make the most continuous change of curvature. I will then do some FEA tests and compare with other longitudinal arches.

[Oded Kishony]

I don't think you can predict in advance what the tonal effect of stresses in the rib structure will have on the overall sound.

The ribs will have an effect on the sound in three different ways:

First, higher frequency sound radiates from the surface of the ribs and enhances the spatial effect of the instrument by directionally radiating sound all around the instrument.

Second, the ribs form a bridge connecting the top and back plates. At low frequencies the entire corpus is moving. The nodal lines run through the ribs at these frequencies and, in so far as the ribs alter the direction of these nodal lines, they can have an effect on how efficiently the plates move in unison and radiate the lower frequencies.

Third, If the ribs have a longitudinal curvature or transverse taper, they can change the overall stiffness of the plates.

You can hear for yourself the tonal effects of the ribs by tapping them with something hard, like the back of a chinrest key, and listen to the open strings vibrating. You'll notice various 'hot spots', especially adjacent to the blocks and the C bouts.

The tonal properties of the ribs have, by and large, been ignored by the academic researchers, but in my own work I've found that they are an important constituent of the sound.

Oded Kishony

[Roger Hill]

The idea is to make the most continuous change of curvature.

You might want to try a three segment chain, the inhomogeneous catenary, as a perfect example of this

[Sore Fingers]

Tell me if this is just weird, but aren't you introducing stress when you bend the ribs, even if they are bent perfectly to fit the mold?

I believe the only way to eliminate that stress is to carve the ribs (3-dimensionally) in the correct shape, not to bend thin strips. Maybe that's the long-lost secret from Cremona!