Bass bar question

[James M. Jones]

While on the topic of bass bars, can someone perhaps shortly (or long if you want to) tell me what is meant by springing the bass bar? A picture would also be most helpful. I tried finding a picture myself, but no luck.

Rather than getting a spot on fit, a sprung bar has the ends raised up a touch,1mm or so, creating a graduated arc inside of the arc of the plate.when glued your still looking for a perfect joint , the top will bend to the bar.

[martin swan]

We experimented a bit with sprung and unsprung bassbars in hardangers.

For an excellent analysis of the results of our experiments, see Brad's post 5 above ...

[DiemViolins]

While on the topic of bass bars, can someone perhaps shortly (or long if you want to) tell me what is meant by springing the bass bar? A picture would also be most helpful. I tried finding a picture myself, but no luck.

It can be done in two ways. The picture below may be self explanatory:

 

The gap is about 1- 1.5 mm depending how much tension is desired.

 

Frits

[Don Noon]

Anyone experiment with different woods or material for bass bars? 

If I could think of a reason to try it, I would.  But spruce is great stuff, and there's plenty of it.

 

Similarly, I can think of no reason that springing a bass bar would do anything, other than to slightly pre-distort the arching.

 

I DID try changing bass bar height, and from the almost undetectable acoustic changes (even with large changes in height), it re-affirmed my lack of interest in trying those other experiments.

[K123]

Thank You for the explanations, James, and Dutchviolins.

[curious1]

If I could think of a reason to try it, I would.  But spruce is great stuff, and there's plenty of it.

 

Similarly, I can think of no reason that springing a bass bar would do anything, other than to slightly pre-distort the arching.

 

I DID try changing bass bar height, and from the almost undetectable acoustic changes (even with large changes in height), it re-affirmed my lack of interest in trying those other experiments.

Yes, spruce is great stuff. And it's amazing how sloppy (forgiving) the structure of the violin is. You have to make large changes to get things to move around.

And I always assumed springing the bar was meant to distort the arch. Either to correct some sinking or change the shape to make the arch stronger.

[Fiddler45]

As to Dutchs post, i have found if you spring the bar the second way, the resulting tone will be deeper . Placement of the bar definitely makes a difference in the finished tone, as does where you put the highest point of the bar.

[Peter K-G]

For optimizing weight and spring (more "woody" and power on G, D)  It is better to have straight cut bass bars like this (10,4 mm, ~3,5 g):

 

 

I use to make them like this, which isn't as good:

 

[Conor Russell]

For what it's worth, there were trade fiddles made with well fitted bars that had a very high bump under the bridge. I can't remember where they were from. They sounded cheap on the bottom strings, but if you cut down the bump and gave them a better shape, they usually sounded good.

[martin swan]

Friedrich Kochendorfer ...? The bump was so big you couldn't see where you'd put the bottom of the soundpost.