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Does the bridge have two points where it rocks carrying the frequencies?


ViolinAnanda

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When studying bridges I've noticed that the most effect on better responsiveness was making waist and ankles thinner. I could change other elements but there was not as much effect.

It seems to me that it's because waist is the point where the upper part is rocking from one side to the other on the same axis as movement of bow. It seems that the same thing is for the ankles (I saw some old threads where people measured rocking frequency attached to ankles).

1. Would you say that the rocking of waist is carrying middle and high sound vibrations, while the rocking on ankles are carrying lower frequencies? (If I make thinner feet I will improve capacity to carry low vibrations. If I make waist thinner I will improve middle and high frequencies responsiveness). Is that your experience too?

2. How one knows what is the optimal thickness for the waist and ankles so, it's flexible enough to allow itself to rock while being resistant at the same time to discharge rocking movement further into energy carried to the top plate? Is there a way without testing and risking overdoing, carving too much? If one makes waist and ankles too thin I think It will rock easily but the energy will flow as badly as in situation where waist and ankles are too thick.

Some say knowing rocking frequency can help but the same rocking frequency with different wood density, volume can have inconsistent results I think.

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While there are many things which can influence rocking frequency a tiny bit, the major contributors (given the same piece of wood ) are distance between the eye cutouts, and mass at the top of the bridge, in diminishing order.
Ankle and foot width and thickness, unless taken to extremes far beyond convention, do almost nothing to alter rocking frequency.

This is not to say that any change on a bridge, no matter how slight, does completely nothing.

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Define "thinner" for us.

If you mean front to back, how are you thinning the ankles without thinning the feet and the area under the waist above the ankles, the "thighs"? And perhaps the waist along with that? And also, if you have a constant taper from top to bottom, perhaps a whole lot else? Or does the profile of your bridge look like an inverted pear?

If in the direction we normally call width, then from 6. mm to 2, from 6 to 4, from 3.5 to 3?

My point being most things you modify don't just happen in a vacuum, not touching something else, and also that there's IN adjustment, but there's also "not there yet" and  "whoops, went past the optimum."

FWIW, my experience does not parallel yours at all. It's more like David's with a few additional things thrown to appease my personal tastes.

An interesting experiment regarding the effects of changes is to take an instrument you're really familiar with that hasn't been messed with recently and play it for a while. Then without loosening the strings push the bridge over to the side 2mm and then immediately push it back. If you have reasonable ears, you should notice quite a difference. Yet what have you changed? Nothing. Now imagine if you'd instead taken the bridge off and thinned the ankles: are you SURE what to attribute the change to? The ankles? Or taking the pressure off the top for two minutes?

In violin work it's extremely difficult, if not impossible, to do an adjustment in isolation without affecting anything else, and likewise to learn anything from one or two cases. For myself, if I start doing something different, I might start to believe it's meaningful 10, 20, 50 instruments later. Or often it only proves to have an effect on some of those, and then you have to figure out how that synergy happens with those instruments so you know when to apply that adjustment. Or on 30% of instruments where that mod might absolutely ruin the sound, why? And what else can you do in that situation?

One violin, three bridges? Meh.

 

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2 hours ago, Michael Darnton said:

Define "thinner" for us.

If you mean front to back, how are you thinning the ankles without thinning the feet and the area under the waist above the ankles, the "thighs"? And perhaps the waist along with that? And also, if you have a constant taper from top to bottom, perhaps a whole lot else? Or does the profile of your bridge look like an inverted pear?

If in the direction we normally call width, then from 6. mm to 2, from 6 to 4, from 3.5 to 3?

My point being most things you modify don't just happen in a vacuum, not touching something else, and also that there's IN adjustment, but there's also "not there yet" and  "whoops, went past the optimum."

FWIW, my experience does not parallel yours at all. It's more like David's with a few additional things thrown to appease my personal tastes.

An interesting experiment regarding the effects of changes is to take an instrument you're really familiar with that hasn't been messed with recently and play it for a while. Then without loosening the strings push the bridge over to the side 2mm and then immediately push it back. If you have reasonable ears, you should notice quite a difference. Yet what have you changed? Nothing. Now imagine if you'd instead taken the bridge off and thinned the ankles: are you SURE what to attribute the change to? The ankles? Or taking the pressure off the top for two minutes?

In violin work it's extremely difficult, if not impossible, to do an adjustment in isolation without affecting anything else, and likewise to learn anything from one or two cases. For myself, if I start doing something different, I might start to believe it's meaningful 10, 20, 50 instruments later. Or often it only proves to have an effect on some of those, and then you have to figure out how that synergy happens with those instruments so you know when to apply that adjustment. Or on 30% of instruments where that mod might absolutely ruin the sound, why? And what else can you do in that situation?

One violin, three bridges? Meh.

 

What has personally surprised me, is that I can tweak the bridge and soundpost to my great satisfsction, but then if I let the violin set untouched for a week, it often goes back to sounding more or less like it did before I went through all the trouble.  Not always, but often enough it seems like some violins just want to sound the way they do, as hard as I try to change them.  

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19 minutes ago, Aston4 said:

goes back to sounding more or less like it did before

Consider that it may be that your hopeful perception of an improvement has evaporated in the intervening time, and that there never was a significant difference. I've certainly managed to convince myself a few times before deciding that I had in fact accomplished nothing.

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3 hours ago, Michael Darnton said:

Define "thinner" for us.

If you mean front to back, how are you thinning the ankles without thinning the feet and the area under the waist above the ankles, the "thighs"? And perhaps the waist along with that? And also, if you have a constant taper from top to bottom, perhaps a whole lot else? Or does the profile of your bridge look like an inverted pear?

If in the direction we normally call width, then from 6. mm to 2, from 6 to 4, from 3.5 to 3?

My point being most things you modify don't just happen in a vacuum, not touching something else, and also that there's IN adjustment, but there's also "not there yet" and  "whoops, went past the optimum."

FWIW, my experience does not parallel yours at all. It's more like David's with a few additional things thrown to appease my personal tastes.

An interesting experiment regarding the effects of changes is to take an instrument you're really familiar with that hasn't been messed with recently and play it for a while. Then without loosening the strings push the bridge over to the side 2mm and then immediately push it back. If you have reasonable ears, you should notice quite a difference. Yet what have you changed? Nothing. Now imagine if you'd instead taken the bridge off and thinned the ankles: are you SURE what to attribute the change to? The ankles? Or taking the pressure off the top for two minutes?

In violin work it's extremely difficult, if not impossible, to do an adjustment in isolation without affecting anything else, and likewise to learn anything from one or two cases. For myself, if I start doing something different, I might start to believe it's meaningful 10, 20, 50 instruments later. Or often it only proves to have an effect on some of those, and then you have to figure out how that synergy happens with those instruments so you know when to apply that adjustment. Or on 30% of instruments where that mod might absolutely ruin the sound, why? And what else can you do in that situation?

One violin, three bridges? Meh.

 

I meant thinner side to side, while front to back remains the same. Maybe i should have used word "narrower' instead

I tried to carve out with precision knife waist while the bridge was on the violin with strings on full tension. I made ankles narrower with precision file also with bridge under full tension. So I could immediately test whats the difference while having everything else at the same configuration in relation to soundpost etc.

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1 hour ago, Aston4 said:

What has personally surprised me, is that I can tweak the bridge and soundpost to my great satisfsction, but then if I let the violin set untouched for a week, it often goes back to sounding more or less like it did before I went through all the trouble.  Not always, but often enough it seems like some violins just want to sound the way they do, as hard as I try to change them.  

I think more that it's that, as I said, disturbing the setup in any small way makes the violin momentarily sound better, and then you have to do your adjustments from that point, knowing that you will lose that initial bump over time. That's why when we're doing really serious in-shop adjustment we'll make the *changes* we want on top of the changed state of the instrument, then set it aside for a few days before deciding if we'd done enough or want to continue. The trick is recognizing the bump change and working around that, thinking towards the future. A bit of a trick but if you do it all the time you get a feel for it.

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1 minute ago, ViolinAnanda said:

I meant thinner side to side, while front to back remains the same. Maybe i should have used word "narrower' instead

I tried to carve out with precision knife waist while the bridge was on the violin with strings on full tension. I made ankles narrower with precision file also with bridge under full tension. So I could immediately test whats the difference while having everything else at the same configuration in relation to soundpost etc.

OK, another interesting test. Take a fresh violin, play and remember, then hold the violin like a guitar and use your right hand to pump the bridge as if strumming it--grab it by the upper corners and rock it back and forth, then try it again.  > change. Anything at all that you do will result in some sort of temporary change. In this context, filing is "anything".

 

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@Michael Darnton you make a good point about the effect of de-tensioning and trying to assess what you have changed.

At the same time, however, I have read a lot of good comments about bridge shaping and effect on tone.  I have an instrument I would like to improve, but what to do?  Until now I have been reluctant to mess with it.

This evening I had an idea.  I have Oire Nomi chisels that are INSANELY sharp, in a wide range of sizes.  I used these to take transparent shavings off the bridge without removing it.  The range of chisel sizes allowed me to comfortably reach anywhere I liked on the bridge (excepting the feet and the very crown of the bridge, of course).

I was able to interactively see the impact of changes I was making, playing the instrument between shavings.  And what a difference small shavings make!  
 

Interestingly, it seemed like thinning the bass side enhanced treble responsiveness and thinning the treble side increased bass resonance (more depth and overtones to bass side tone).  Has anyone else seen anything like this?

I also find that I need to adjust my bow technique to the new bridge.  I can get MUCH greater color range out of the instrument, but it is also easier lose control and have its voice break.

I will play it for awhile and see how it all holds up after I adjust to the changes… and see if I went too far.  At this point I don’t think so.

At some point I will take it off and measure the changes.  Nowhere did I take off more than 0.1mm… but the difference is profound.

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10 hours ago, ViolinAnanda said:

2. How one knows what is the optimal thickness for the waist and ankles so, it's flexible enough to allow itself to rock while being resistant at the same time to discharge rocking movement further into energy carried to the top plate?

Optimal is what a player of the instrument likes.

Theoretical calculations might give you ideas, but in the end it’s wiser to know which pre conditions make you alter which proportions on the bridge. Or for an oversimplified example: a stiff top plate and a flexible top plate need different bridges (with some other parameters in the setup)

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9 hours ago, Shunyata said:

Interestingly, it seemed like thinning the bass side enhanced treble responsiveness and thinning the treble side increased bass resonance (more depth and overtones to bass side tone).  Has anyone else seen anything like this?

If we took this to the logical conclusion, it seems like a thinner bridge would be a better one.

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1 minute ago, Michael Darnton said:

If we took this to the logical conclusion, it seems like a thinner bridge would be a better one.

That doesn’t really follow.  We only know that a too thick bridge is a poor one.  

Would need to keep thinning to demonstrate a too thin bridge is a poor one.

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