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Soundpost placement symmetry


Sam Howell
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So, I understand from Trianglestrings that soundpost placement (on cellos, at least) should be symmetrical with the bar, i.e., placed at the same distance to the centerline. This determines the bridge width which will vary considerably (in cellos) because of the wide variance in bar placement. I hope I am understanding this correctly @PASEWICZ

So what about violins? I am working on a post/bridge for an old dutzendarbeit with the bar placed at 16mm from the CL. If I place the post symmetrically to the bar, a standard 42mm blank will overhang 5mm on each side. This seems problematic.

So what do you guys do for post placement on instruments with narrowly-placed bars?

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1 hour ago, Sam Howell said:

...I hope I am understanding this correctly...

You are.

 

1 hour ago, Sam Howell said:

...what do you guys do for post placement on instruments with narrowly-placed bars?

Though it may noy be optimum tonally because it violates this symmetry rule, I use a standard-width bridge and fit the post in line with the bridge foot.  To make everything symmetrical, the alternatives are to use a different bridge width or to move the bass bar.

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There may be good underlying acoustic reasons why the bass bar is aligned (mostly) with one bridge foot and the soundpost is aligned (mostly) with the other foot.  But beyond that, imposing rigid symmetry just because there is a "symmetry rule" seems arbitrary to me.  The soundpost should go where it works best for the player, which is the ultimate goal.

For the OP question about narrowly placed bars... use a narrower bridge would be #1.  If the F eyes are wide enough and you want to put in the time:  new bar.

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35 minutes ago, Don Noon said:

...imposing rigid symmetry just because there is a "symmetry rule" seems arbitrary to me.  The soundpost should go where it works best for the player, which is the ultimate goal...

I agree completely.

But if the soundpost can go anywhere and the bass bar can go anywhere, then trying out all the different possible positions of both in an attempt to optimize the sound would impractical.  Besides the aesthetic appeal of symmetry, I think that the reason for this particular symmetry rule might be simply to eliminate some variables to make set-ups practical.  There are already too many other variables.

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1 hour ago, Brad Dorsey said:

Besides the aesthetic appeal of symmetry, I think that the reason for this particular symmetry rule might be simply to eliminate some variables to make set-ups practical.  There are already too many other variables.

For new making, it certainly makes sense to have a general standard.  But in the case of an existing instrument, where the bass bar is already there and closer to the centerline than standard (which is the specific OP question), there are two choices as I mentioned... either give up on the "standard" 42mm bridge, or change the "non-standard" bass bar.

Going with a narrower bridge... or even a 3/4 bridge... would be far preferable, as it is reversible.  Changing the bar depends a lot on the skill and experience of the luthier, and IMO wouldn't be a tranformative improvement anyway.  Could even be slightly worse, but hard to say anything with confidence, especially without knowing the other construction features of the given instrument.

In any case, the soundpost should end up where it works best, rather than any precise symmetrical dimension.

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1 hour ago, Don Noon said:

For the OP question about narrowly placed bars... use a narrower bridge would be #1.  

Ok! That makes sense. 

 

1 hour ago, Brad Dorsey said:

  There are already too many other variables.

Like, using a 1/2-sized bridge (35mm MENC) on a 4/4 violin is obviously not practical. And even if you could make one, wouldn't it "rock" too much if the feet were placed so closely together? (I'm imagining a theoretical bridge that simply tapered from a standard width at the top of the arch to a narrow stance.) 

So, for a 32mm edge-to-centerline bar placement the solution is: I've got lousy bar placement and there are no good solutions, but putting the post at 21mm from the CL is better than trying to center it.

Do you guys get a lot of these? I seem to get several each year.

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1 hour ago, Don Noon said:

Going with a narrower bridge... or even a 3/4 bridge... would be far preferable, as it is reversible.

Is this something you've done much? I've done it a few times (and I do it on cellos all the time) but I'm pretty new to this and I haven't done any A-B testing on it. The cut is pretty different (in absolute terms) from 4/4-3/4 bridge. Do you compensate with more or less carving on eyes, wings, etc?

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Given the state of affairs, I'd wager that the entire violin is of such poor quality, that whatever decisions you ultimately decide to make, will make very little difference.

Better to save wasting more time, and just move onto a better example, with at least some potential.

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I just measured a few of the "42mm" bridges I have, and the distance between the center of the ankles runs between 30 and 32 mm.  So it a bass bar is 16 mm from the centerline (is that to the inside, or center??), I'd say the alignment isn't too bad.  The ankles is where the force comes in, and the feet just spread it out.

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15 minutes ago, Don Noon said:

I just measured a few of the "42mm" bridges I have, and the distance between the center of the ankles runs between 30 and 32 mm.  So it a bass bar is 16 mm from the centerline (is that to the inside, or center??), I'd say the alignment isn't too bad.  The ankles is where the force comes in, and the feet just spread it out.

Unfortunately, I'm measuring to the outer edge of the bar. On this fiddle, the ankles will be nearly beyond the bar!

 

1 hour ago, Wood Butcher said:

Given the state of affairs, I'd wager that the entire violin is of such poor quality, that whatever decisions you ultimately decide to make, will make very little difference.

Better to save wasting more time, and just move onto a better example, with at least some potential.

Probably true. It does seem to be a not-too-uncommon situation, though, and I'm hoping to learn what the best practice is for these narrowly-placed bars.

 

Thanks for all of the feedback, guys.

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1 hour ago, Sam Howell said:

Unfortunately, I'm measuring to the outer edge of the bar. On this fiddle, the ankles will be nearly beyond the bar!

 

 

38mm bridge will have the ankle on the bar. Best practice is to choose a bridge width that works as well as possible with the bass bar position.

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7 hours ago, Guido said:

You can also try to place the bridge slightly off centre to get the bass foot closer to the bar. 

I'd rather eat my own ear wax.

I agree with Wood Butcher that whatever you do is unlikely to lead to a leap in performance of this instrument. But if you fit a narrow bridge commensurate with your bass bar position, you'll at least look like you know what you're doing :).

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When I set a new sound bridge and post, I generally fit the bridge to the distance between the f-hole eyes, observing the overhang relating to the bass bar. That's usually within norms. As far as the post and symmetry goes, that's determined by "what works", and final location is determined by sound, but the most important thing is to get a perfect fit of the top and bottom.

When I fit a sound post, I start from the inside out, I get a good fit top and bottom, and gradually move the post "east", trimming just a whisker at a time until I have the general tonal balance and character that I want. Some customers want a smoother sound, or a stronger G, some want a growlier sound. Some want changes in the treble sound, which is, for me a final N/S adjustment. Once we're close, I leave the instrument to be played for a time and to settle in, at which time final tweaks can be made. This isn't necessarily a long involved process; it depends on how the instrument responds and how much time one wants to spend with it.

 

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