Sign in to follow this  
violins88

Tuning a bridge

Recommended Posts

Tha tradesecrets.com website has a pic of a violin bridge in a vice, and apparently a thread pulling on the bridge. I think the thread is pulled until it breaks, whereupon the sound is recorded on the iPhone so that the rocking mode frequency can be measured.

 

How many of you use this method? Looks simple to me.

 

Rozie%202019_edited-1.jpg?itok=O4xriWhl

Share this post


Link to post
Share on other sites

I suspect that bridge tuning will give inconsistent results for the same reason as "plate tuning": a heavy and stiff bridge can have the same resonance frequency as a light and flexible one.  I very much doubt they would perform the same. 

Share this post


Link to post
Share on other sites
41 minutes ago, violins88 said:

I think the thread is pulled until it breaks...

That's one method.  I think that tapping with a very light "hammer" is far easier, and should give the same result.

I haven't been doing either one, though.  I should... it's not that hard to do, and I could fatten up my database of numbers that may or may not be useful sometime.

19 minutes ago, Marty Kasprzyk said:

I suspect that bridge tuning will give inconsistent results for the same reason as "plate tuning": a heavy and stiff bridge can have the same resonance frequency as a light and flexible one.  I very much doubt they would perform the same. 

Agreed.  I think that mass is by far the more important factor, unless you get really out there in terms of bridge flex.

Share this post


Link to post
Share on other sites

Yes, I should have made clear that the mass nearest the strings is the really important one.

In theory, a more flexible (lower tuned) bridge should increase the amplitude of frequencies near its rocking frequency, and attenuate frequencies higher than that... with the caveat that the "rocking frequency" is what it has on the instrument, with strings on... which may not bear much relation to what you'd get with a bridge clamped in a vise.  It may be that the strings and flexibility of the violin body mangle the nice, clear bridge resonance.

In practice, I have looked for the theoretical effects, and not been able to find them.  I did, however, find that if you go extremely high on the flex, the higher frequencies do die off.  I never have seen the theoretical enhancement effect.

Share this post


Link to post
Share on other sites

Please provide a link.

What kind of thread, and what part of the bridge is it tied to? I have some thread that would rip the top right off the bridge.

Share this post


Link to post
Share on other sites
4 hours ago, Don Noon said:

Yes, I should have made clear that the mass nearest the strings is the really important one.

Try snapping the arms off of  a bridge in place so you can hear a before/after, and I think you will get some respect for the effects of weight in other places than just along the top. :-)

Share this post


Link to post
Share on other sites

I've seen all kind of experiments with tuning a bridge......generally the bridges used were not good. When I hear luthiers talking about tuning violin parts I kind of tune out. Tuning needs to be left to the musicians...wood  moves with the climate......just out of tune sounds awful.

 

Share this post


Link to post
Share on other sites
2 hours ago, FiddleDoug said:

Please provide a link.

What kind of thread, and what part of the bridge is it tied to? I have some thread that would rip the top right off the bridge.

I found the pic at learningtradesecrets.com. Just guessing that the weakest thread you can find will work.

Share this post


Link to post
Share on other sites

Though it might take some effort, I bet you could tune a bridge that is 4.5 mm at the top and 1.3 mm at the bottom to the same frequency as one that was normal. And I am betting they would sound very different from each other.

Share this post


Link to post
Share on other sites
1 minute ago, Michael Darnton said:

Though it might take some effort, I bet you could tune a bridge that is 4.5 mm at the top and 1.3 mm at the bottom to the same frequency as one that was normal. And I am betting they would sound very different from each other.

Ha ha!!! Loved it! I would like you in my law office Michael!!!

What I see is that when the instrument is excellent, the first good set up will work well right away. It can get better, but will sound good from the first set up.

On the other hand, when the instrument is bad, you will can try many things that will not work. Bad instruments will not respond well, they are like when you are playing an instrument that does not response well.

Share this post


Link to post
Share on other sites
3 hours ago, Michael Darnton said:

Try snapping the arms off of  a bridge in place so you can hear a before/after, and I think you will get some respect for the effects of weight in other places than just along the top. :-)

I've improved a stubborn instrument by snapping the arms off a bridge. It gave me a lot of respect for the effects of weight in that are of the bridge.

Share this post


Link to post
Share on other sites

If you are just looking for the first few resonances, a simple scratch with the fingernail will do. Or drop it on a solid table top.

To substantially change the bridge resonance, one must remove a lot of material to the point where the structural integrity will be compromised.

To substantially change the bridge response amplitude, a much smaller amount of material in key places can be used.

The main rocking resonance of a bridge is well beyond the fundamental frequency of most of the notes that can be played on a violin. This means that reasonable bridge tuning cannot do very much to change the core tone of most of the notes.

The main bridge resonance does fall in the frequency range where the human ear is most sensitive. So by trimming the bridge in a way that increases (or decreases) the response amplitude, one can affect the perceived brilliance and loudness of the violin by affecting the higher frequency modes of the notes.

Basically, if your violin sounds  like cr@p, there isn't anything bridge tuning can do to fix that. But if you want a little more brilliance or loudness, think about removing material form the waist on up in a way that does not compromise the ability of the bridge to hold up the strings without warping.

 

 

 

 

Share this post


Link to post
Share on other sites
7 hours ago, ctanzio said:

. . . This means that reasonable bridge tuning cannot do very much to change the core tone of most of the notes. . . .

. . . Basically, if your violin sounds  like cr@p, there isn't anything bridge tuning can do to fix that.

You would be surprised by how much difference a bridge can make.

Share this post


Link to post
Share on other sites
4 hours ago, Michael Darnton said:

You would be surprised by how much difference a bridge can make.

Agreed. Not only with sound but how it feels or responds when you play. Granted there are limits of improvement. Skilled players will notice.

Share this post


Link to post
Share on other sites

John, another method is to use FFT software and a small, inexpensive sensor wired to your smart phone.  (I cannibalized an old set of ear buds.) 

I am sure there are lots of ways to make different parts of the bridge resonate, including flicking the chamfered side.  There are so many variables to take into account that, if you are looking for great precision (as in comparing bridges) that it seems like it would take the kind of intensity they apply to the work done at the Oberlin acoustics workshop.  My opinion. 

Variables such as: keeping the placement and force of the impact constant, maintaining the same clamping pressure and location on the bridge when placed in the vise, wood source/quality of the bridge,...All of that is a bridge too far for me (sorry).  I just use the sensor and the FFT software and shoot for a certain range in the response.

 

Fast Fourier Transform spectrum analyzer: lots of freeware online, but I selected this one.  I like the display options it provides.  

http://allbestapps.net/android/fft-spectrum-analyzer

I can't find a record of my purchase of the sensor, but I'll take a picture and post it.

 

BTW, Joseph Curtin has an article on bridge acoustics in the November issue of The Strad.

Edited by Julian Cossmann Cooke

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.