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Ken_N

Viola Bass Bar

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Koo Young has a post on thicknesses from a physical standpoint.  Would that be transferable to the bass bar as well?  I'm fitting two bass bars now.  The violin I have ready to glue.  I rough the thickness down to 15 mm, and then tapering down with 1.11 squared, cubed, you know regualr practice.  I figure then It is somewhat in the ballpark; I can taper the sides and cut the top to suit.  I have no idea what to do a viola at.  Using the formula, my viola that is 1.2 times bigger would need a bar ath 16.9 to start, compared to the 15 for the violin.  if the bar was 1.2 times tall in scale with the length it would start at 18.    The top is very low, maybe 16.5 mm, and withouit a bar and the f holes in it rings at C4.  

Is 16.9 mm a reasonable start?

Ken

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Stroebel lists the following measurements for viola bass bars :   For 17"; 334mm long,  6.6mm thick, 15mm high at bridge    For 16"; 319 mm long, 6.3mm thick, 14mm high at bridge   For 15 1/2", 303mm long, 6.0mm thick, 13mm high at bridge. I'm not quite sure what you are doing.

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The violin will finish at 14, I just rough in the shape a little high.  Apparently 14 is high for a violin?  Viola bars are not any higher?

Ken

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The violin will finish at 14, I just rough in the shape a little high. Apparently 14 is high for a violin? Viola bars are not any higher?

Ken

14mm high is fine for violin (measured without the thickness of the top). 16mm for viola seems ok. It leave it high, put it all together, see how it plays and then decide if it needs to be lower. It's much easier to lower it than it is to make it taller. :^)

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14mm high is fine for violin (measured without the thickness of the top). 16mm for viola seems ok. It leave it high, put it all together, see how it plays and then decide if it needs to be lower. It's much easier to lower it than it is to make it taller. :^)

[/qu 14 mm. including the top, no?

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14mm high is fine for violin (measured without the thickness of the top). 16mm for viola seems ok. It leave it high, put it all together, see how it plays and then decide if it needs to be lower. It's much easier to lower it than it is to make it taller. :^)[/qu 14 mm. including the top, no?

14mm plus the top. That's about as big as I'd go but I go there all the time.

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I have always wondered what effect lowering the height (within limits of course) of the bass bar has on the sound.

No definitive answer here. It depends on the relative stiffnesses of the top and the back. If the top is too stiff sound the sound will improve. If the top is already weak the sound will be even worse.

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14mm high is fine for violin (measured without the thickness of the top). 16mm for viola seems ok. It leave it high, put it all together, see how it plays and then decide if it needs to be lower. It's much easier to lower it than it is to make it taller. :^)

 

 

14mm plus the top. That's about as big as I'd go but I go there all the time.

 

curious1:

 

These seem to be conflicting statements. First, let's talk about the peak height of a violin bass bar measured from the inside belly surface to the peak of the bass bar. I was told to keep this to 12 mm or less. Is that right or wrong?

 

Do you feel that the bass bar height MUST be measured to include the belly thickness? I am curious why because I thought the bass bar height was determined by the properties of the entire belly, not just the thickness under the bass bar peak.

 

Please correct my misconceptions.

 

Mike

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curious1:

These seem to be conflicting statements. First, let's talk about the peak height of a violin bass bar measured from the inside belly surface to the peak of the bass bar. I was told to keep this to 12 mm or less. Is that right or wrong?

Do you feel that the bass bar height MUST be measured to include the belly thickness? I am curious why because I thought the bass bar height was determined by the properties of the entire belly, not just the thickness under the bass bar peak.

Please correct my misconceptions.

Mike

I make my bass bars up to 14mm high excluding the thickness of the top. That is measured with a ruler on the inside edge of the bass bar. I do measure the bar with the top too (easy enough to add the thickness of the top and come up with a number) and that is the more accurate method for the reason you mention.

post-53756-0-04970200-1418930751_thumb.jpg

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I seem to remember a Strad article on installing  bass bars by Joseph Curtin similar to what C1 says where the max height was 14mm measured from the internal belly surface  but the bar was much reduced in thickness as it approached that height to reduce weight while keeping strength. There is a good master to learn from. EDIT AS well as C1

I have tried all kinds of bar combinations. A lot of folk get hung up about what the depth of the bar can withstand in terms of string pressure. My current personal preference is a bit of a refuge after trying a lot of stuff. Currently for new work I do something like the 'modern bar' in the Hill Stradivari book and take it from there.

One think I will generally do use is ( unfashionably?)a bit of tension. Once tension comes into factor the longitudinal strength of spruce comes into play via lamination  and this has much more strength than 2mm on the depth of the bass bar. As far as I am aware the general consensus is that string pressure in  Strad's time is similar to modern.  Given the small size of the Strad bar and my experience so far as a luthier I can only say that that tiny bar was possibly masterfully sprung in. using the rigid long grain strength of spruce to create stiff low mass vibrational structures...I think other luthiers making lutes etc were/still are springing stuff aware of how wood grain could support it and still are

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BTW, I want to add this observation: I notice that some of the experienced makers pop the top to make tonal adjustments. This includes bass bar adjustments and some top plate scraping. This is a topic not usually mentioned.

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BTW, I want to add this observation: I notice that some of the experienced makers pop the top to make tonal adjustments. This includes bass bar adjustments and some top plate scraping. This is a topic not usually mentioned.

If you want to make great instruments I think is obligatory. Consider the fact that Stradivari violins were probably very great to begin with but also have the benefit of 300 years of the best luthiers bringing/keeping them to perfection.

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If you want to make great instruments I think is obligatory. Consider the fact that Stradivari violins were probably very great to begin with but also have the benefit of 300 years of the best luthiers bringing/keeping them to perfection.

 

Given that the same best luthiers have consistently failed to make violins remotely close to Strad's best, one thing is clear :  Strads were incredibly great to start with. :)

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Given that the same best luthiers have consistently failed to make violins remotely close to Strad's best, one thing is clear :  Strads were incredibly great to start with. :)

This old axe again, eh? Yer WRONG, Carl! hahahahaha

Except for the incredibly great to start with part.

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This old axe again, eh? Yer WRONG, Carl! hahahahaha

Except for the incredibly great to start with part.

 

Could be. I'm often wrong. Would you care to supply an example of modern maker's work as good as Strad's best. "Soil class" I mean... 

But I think now you've just discovered you have urgent matters to attend to. :) :) :)

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If you want to make great instruments I think is obligatory. Consider the fact that Stradivari violins were probably very great to begin with but also have the benefit of 300 years of the best luthiers bringing/keeping them to perfection.

Perhaps some of the best luthiers, but also wrecked by some of the worst luthiers over the past 300 years. Techniques and theories have varied so much over the past 300 years that it's difficult to find an "untouched" instrument. Fact is that quite a few Strads are not that good, and a lot of modern makers easily surpass many Strads in sound quality.

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Given that the same best luthiers have consistently failed to make violins remotely close to Strad's best, one thing is clear :  Strads were incredibly great to start with. :)

Not sure we can say one way or another since there isn't a single Stradivari that has come down to us in original condition.

Certainly many must have been of the highest caliber but some of them were probably just very good and some just average. He was not a god just incredibly skilled and industrious.

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