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David Beard

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Posts posted by David Beard

  1. A few things.

    If you go out looking to buy 'Venice Turpentine' these days you will in most cases be sold rosin thinned out with turpentine spirits.  For most commercial purposes that is what passes as Venice Turpentine these days.  So specifically buy Larch Balsam.

    These material remains very mobile, even when you cook off the volatile components.  This persisting mobility is very good for clarity right at the wood surface and into the wood surface.  But, an out varnish with too much portion of VT may not be stable enough to hold a polish.

  2. 4 hours ago, Andreas Preuss said:

    I tried already the reverse (thinning down) and I couldn’t hear any significant changes. So my logic is to stiffen that area.

    ‘Already strong’ is very relative. Looking at the three points where string forces act on the body (neck heel, bridge, lower nut) the neck with its leverage force applies the strongest forces on the body. Restorers know that thickness of the top around the top block is important for the neck.

    I think it's better to trust what we see in the classical examples.  Namely in the upper bout that is:

    a) Comparatively wide channels.

    b) Medium strong edge and lining work. (weaker than cBout area, but stronger than lower bout work)

    c) Light or no bass bar extending very far into the upper bout

    d) for top only, elevation of long arc sustaining partly or significantly into bout area. Meaning peaks of cross arches stay relatively high.

    e) relatively thinned top plate in upper bout (perhaps patches of thinness instead of even theough bout)

     

    Combined, these things leave the arched portion of the plate comparatively thinned and mobile and separated from moderately solid edges.

  3. 5 hours ago, Thomas Knight said:

    Hi David, I guess it is because I never like conventional thinking. It is hard to argue with 300+ years of bowed instruments and the experts that carry on that tradition. Maple is the standard bridge wood and has a Janka Hardness of 1450. Why was/is maple considered the only proper wood for a bridge? Ease of access? Maybe with treatments maple can achieve Janka 1550. My mind says why not try unconventional woods? What happens if we go even harder to rosewood or bamboo? Maybe a different wood will have greater transmittal of frequencies with certain instruments. Maybe a softer wood is better in some cases.

    As a former golf pro I worked with building clubs and the shafts were grouped into 3 categories by how much they flexed on a scale with a weight at the tip and the handle end held securely. Then in the early 80's a researcher discovered frequency testing and flex categories jumped in number. Aluminum shafts, fiberglass shafts, titanium shafts, etc were tried. Then composites were developed and can isolate certain frequencies and improve response to certain frequencies that you 'feel' when hitting a golf ball. At the pro level golf is 95% sensory.

    I am not a great violinist but was classically trained as a violist and can hear huge differences between two bridges, two soundposts, strings, tailpieces, and within adjustments of all of those. Tailgut lengths, achieving the proper length ratios, etc. It seems there is room for improvement, especially on student level instruments.

    I'm being sarcastic.  I do understand that many people come to violin making excatly this way.

    I understand the actual motive.  But, it still baffles me that people actuslly follow this impulse instead of letting the thought pass through and then out of the mind without turning into action.

    If a university near you has many years collection of Strad magazine, it makes for amusing reading.  You can see over a hundred years of attempts to innovate around the  violin.  But, it remains a very established classical musical icon. 

    Think of it like an historic variety of wine that has become cherished and classic. You can't satisfy the market for that cherished wine by making varieties.  But then down market there's a demand for any cheap buzz.  This crowd will buy any novel variety you can dream up.  But they also don't care.

  4. 4 hours ago, Marty Kasprzyk said:

    The complicated violin shape and arching are merely Baroque period fashions aren't necessarily any better sounding than simple flat sided boxes of appropriate size.

    1) a curvy outline enhance the contrast between 'plain of plate' pliability versus 'plain of rib' stiffness.   (Physical difference)

    2) coming in at the waist aids playability.

    3) trapezoid and simplified violins had well publicized and examined runs in early 1800s, but not success.

    4) the complicated arching and shapes as evolved support the sound well.  And have been greatly successful.

  5. 4 minutes ago, Andreas Preuss said:

    Yes, but I would say it is a bit audacious to think that ALL trial and error was for the purpose of sound (let alone our obsession of ‘projection’)

    In my view Stradivari was the one who redefined something fundamentally in this tradition which made his instruments outstanding. Any reports from musicians make the comparison between Stainer and Strad and describe Strads instruments as low arched creating a ‘powerful’ sound (whatever this meant in the 18th century)

    Ihave some doubts that this can be explained on a purely geometry design driven level. What I rather see is that Strad changed materials and size of linings and apparently figured out that top weight DOES matter in combination with the right material. Last not least trial and error based arch design is certainly much easier when always working with wood from the same tree.

    The essence of their cultural evolution and success is that none of them started over.  They all stuck to tinker with different combinations of traditional choices, reuses of traditional choices, and occasionally small extensions.

    It was a VERY conservative process.  

    With the geometry choices, we have the advantage of being able to see them fairly directly and completely.  And you can look at their choices and compare from instrument to instrument.  Stradivari wasn't some renegade reworking the system. He mostly made just slightly different combinations of the same choices you can observe being used in other earlier making.  He did quite a bit of returning to Andrea Amati.  Much more than being innovative, he was just probing and effective.

    As with the evaluations and directions of exploration, I agree isn't wasn't all just sound/playing evaluation.  Strad particular seem to explore refinements of choice aiming for the visual.

    But also, it seems they pursued 'notions' to some extent.  This is very clearly evident in Del Gesu foe instance.  He for example pursued elongating the extension of the soundhole shape above and below the eyes.  And, as you pointed out, Strad pursued flatter top arches rather more than had been done.

     

  6. 13 hours ago, Andreas Preuss said:

    I ignore facts which claim things I can’t verify in experiments in an audible way. I always need to hear something. So on the other hand, even if I get a completely different graph and don’t hear anything it’s just telling me don’t go further. In the end I only need recipes which work. I leave the explanation to those who have the knowledge. 

    Remember, the Northern Italians already ran a continous series of these trail and evaluation experiments, for over 5 centuries.  They carried this on from late medieval times until the early phases of the industrial revolution disrupted the continuity of their making tradition.  

    Across countless iterations of bowed and plucked lute type stringed instruments, they explored differing choice in the making, and evaluated results the way you describe.  Not by knowing why something they tried worked, but by deciding if it work. By judging results by eye and ear rather than good or bad theory.

    And, they essentially encoded their learning in traditions of preferred geometry and proportion choices.

    All of their centuries of collective learning informed the violin, leading to its peak of success in the preferred traditional geometry choices of late Cremona makers like Strad and Del Gesu.

     

    Like others, I also enjoy enjoy trying to understand why violins behave as they do.  But this is a very separate curiousity from seeking to know how to build good violins.

    Consider some of the more definite experimental results from this thread.  We have for example the concrete results that both a too thick top and a too light treatment of linings/edges are bad.   But the examples of the old masters already told us not to do those things.

    Scratching the itch to understand is one thing.  But to improve our making, it's probably much more efficient to focus on learning the ways of the old masters.  Their traditions of structured geometry choices embed over 5 centuries of collective learning from trial and aesthetic evaluation tinkering and exploring.

  7. 9 hours ago, chiaroscuro_violins said:

    A $66 dutzendarbeit does not have historical value.  A standard dimensioned bass bar would likely increase its worth as a musical tool.  I'm not advocating for modification of legit violins.  

    This is very wrong headed.  

  8. 46 minutes ago, Andreas Preuss said:

    Here I am not sure at all. If the tripled linings on the top changed anything to an audible degree it was ‘overtones’. So without trying to figure out why, it is on my ‘recipe list’. 

    I think this is the exception to my point.  The extra strength in the linings, particular through the cBouts, helps make the top in comparison more flexibly or independently movable.  

    My point was more that many of the shaped elements, like the center back mass, the archings, the bar, the post, even the way the soundholes cuts up the plate, these are about enabling certain modes of vibrations, but lower ones.

    The freedom and strength of higher frequencies depends mostly on just a few specific aspects of the instrument.  I think these include sufficient thinness in the top plate and the 'daiphragm' parts of the back, thinness in the actual ribs, contrasting 'out of plane' strength in the sides from the working of linings and edges and approach to edges, and on the bridge table and it's relationship to post bar and bridge.

    There could be other specific factors. But these are the ones I see so far.

  9. A things come to mind.

    Most of all, as others have said in this thread already, the strings themselves and player are the source of the high overtones.

    So that implies that the violin's job is not to create those formant high tones, but to give them a place to build energy and then radiate as strong component of the 'signal'.

    The other thing is that these higher frequencies components correspond to a patchwork of physically short standing waves in the plate, and a patchwork of physically smallish air volumes in the air body.  

    This suggests that larger scale design elements like the bar and the arching would be comparatively less significant for these frequencies.  

    But a big factor would be comparatively thin and flexible plates that can readily break up into a patchwork of driven standing waves.  But the plates need to balance this by also being thick enough to move in more unified ways for lower modes of vibration.

     

  10. 1 hour ago, Don Noon said:

    As I understand your thinking, no.  

    The natural frequency of any system is governed by (k/m)^.5, where the spring rate k is the addition of the rates of the "opposing" springs.  The don't oppose... they add together for the net spring rate.

    Also, the spring rate, and therefore the natural frequency, are independent of how much the springs are pre-compressed, or loaded, unless you happen to be using non-linear springs.

     

    53 minutes ago, David Beard said:

    That can't be a complete picture.  If I take a spring that barely begins to stretch with 10lb load, say it stretch 5mm.  And, if I pair this with another spring that stretches say 60mm with an 8ounce load.  Well, if I trap something of negligible weight between these, the lighter spring will only barely be able to engage the heavier spring.  You will be technically correct. But the combined system will behavior very much as the unloaded heavier spring would.  That is that light pulls on the trapped object would only barely stretch.

    I guess the core intuition of my earlier suggestion, that part that is either right or perhaps wrong, is the intuition that if you trap something between two of the heavy springs, and then stretch them a total 60mm, it should now take less than 10lbs force to move the trapped object 5mm.

    Hmmm?

    I think I'm seeing.  Seems I have some bogus notions floating around in my thoughts about springs and oscillation.

  11. Just now, Don Noon said:

    As I understand your thinking, no.  

    The natural frequency of any system is governed by (k/m)^.5, where the spring rate k is the addition of the rates of the "opposing" springs.  The don't oppose... they add together for the net spring rate.

    Also, the spring rate, and therefore the natural frequency, are independent of how much the springs are pre-compressed, or loaded.

    That can't be a complete picture.  If I take a spring that barely begins to stretch with 10lb load, say it stretch 5mm.  And, if I pair this with another spring that stretches say 60mm with an 8ounce load.  Well, if I trap something of negligible weight between these, the lighter spring will only barely be able to engage the heavier spring.  You will be technically correct. But the combined system will behavior very much as the unloaded heavier spring would.  That is that light pulls on the trapped object would only barely stretch.

    I guess the core intuition of my earlier suggestion, that part that is either right or perhaps wrong, is the intuition that if you trap something between two of the heavy springs, and then stretch them a total 60mm, it should now take less than 10lbs force to move the trapped object 5mm.

    Hmmm?

  12. Just thinking about coiled metal springs as an analogy for other systems of mechanical oscillations, obviously there are physical boundaries to free oscillation behaviors, and related driven behaviors.

    The conditions for free oscillation of a weight hanging from the string in two points.   1) the spring must be sufficiently load to stretch.  2) the load must not overwhelm or break or plastically deform the spring.

    These can reduce to one condition that the spring and the mass reasonable balance each other.

    It seems possible to me that both the string tension and the post tension may need to be rather high to load the twisting of the treble side bridge table and allow that dynamic to act as an admittance path for high frequencies as deflections of the plate.

    Also, a spring loaded by a free weight is not as good an analogy for this twisted bridge table analogy as would be something trapped between two oppossing springs that are loaded by stretching. 

    In this analogy, the weight of the trapped something is not necessarily a primary factor. And, in fact, the something could be more of transmission point than the main thing being oscillated or driven. It could even be something like a transmission lever.

    But, the interesting thing here is that a close good balance between the opposing springs would greatly contribute to the freedom in this kind of system.

     

    Perhaps that is what's happening, why the tensions matter.   The twisting dynamic is present at all until you introduce the opposition of the post and loaded bridge foot.  And, the dynamic isn't basically free unless the post tension and string tension are both sufficient.  And, the dynamic isn't very very free until the tensions find a good balance.

     

    It's an idea. And at least it roughly confirms to setup experiences.

  13. 50 minutes ago, Don Noon said:

    Seems like there's the continuing concept of static stress somehow influencing body vibrations, which to first order it doesn't.  If you want to think about static stress squishing out some micro-clearances between the top and the post or bridge foot, which would change mode stiffness primarily in the higher frequencies... go ahead.  I have no measurements to argue with for or against.

    Ok. I think I get the point.  As long as the static load is enough to preengage all the material flexes involved, and not so much as to crush or overwhelm any of the flexures, then the amount of load doesn't change material stiffnesses or the system in that way.

    However, intuitively something stills seems wrong in this.

     

    It seems like the tension of the post setting matters greatly in terms of practical results.  But how can this tension be important but the string tension not be important.  That's confusing.

  14. 12 minutes ago, Don Noon said:

    According to my measurements and rough calculations, string tension might add ~2% to the structural stiffness of the body at the bridge... IF the string deflection is 1:1 with the bridge motion.

    However, the relevant factor is the mode center of rotation relatve to the nut/saddle line... i.e. if the mode rotation is about that line, then the string isn't being deflected in a way that causes a string restoring force.  And most modes that I am aware of have centers of rotation rather close to that line.

    It ain't gonna be much.  

     

    What I'm mostly think of is the twist of the bridge island by the post pushing up and the treble bridge foot pushing down.

    The downward push of the bridge foot is almost entirely from the strings.

    Changes in this little twist seem likely to be the quickest and therefore the highest frequency movements of the top.

  15. 1 hour ago, Don Noon said:

    Why?  Mass will be unchanged, so the stiffness of the body would have to change.  How does string tension change the stiffness of the body?  

    One thing that will change: tailpiece mode frequencies as determined by string/tailgut suspension, and those can certainly impact what the instrument does.

     

    Maybe I'm wrong. 

    Won't the cantilevered twisting relationship between the post, treble bridge foot, and the treble area of the bridge foot change?

  16. I'm not so sure for a driven system that string tension is quite so irrelevant?

    I suspect the post and bar, in relation to the bridge feet and string tension serve as a sort of crossover system that is quite sensitive to the string tension.

    For some frequencies, the post will look immovable, and for other frequencies it will look movable.  Same with the bar.  The frequencies that can move the post and bar I suspect will change with a large change in string tension.   And, these things will change the balance of frequencies and energy that travel certain physical paths and drive certain parts of the violin and it's response.

  17. I think basically so.

    I believe electrical theory includes the notion that energy will take the easiest path.  And I think a similar thing happens with vibrations.

    But with vibrations, it seems to be frequency dependent.   

    High frequencies and high noose seem very ready to roll around in anything that kinda of presents as a stiff shell.

    Lower frequencies want to setup as standing waves, either at a natural resonance frequencies, or driven at a frequency not too far from a resonance.

    But it seems to take a bit more energy for these lower waves to set up.  When that doesn't happen, energy seems to readily go instead to higher harmonics and high noise.

     

  18. 48 minutes ago, sospiri said:

    Two different instruments. Old and new. 

    If the neck is longer, should the plates be thicker? Is a 60-65g belly better for a 229-330mm string length than 70-75?

     

    No.  The favored concert instruments today are the classic instruments with their old build but a modern setup.

    That is what I'm undertaking with 'Cremona Revival'.   The old build process and design choices, with a modern setup.

  19. 37 minutes ago, sospiri said:

    A nailed on neck 1cm shorter? 

    So that is a choice.  The old Cremona masters only made 'Baroque' instruments.  Later people have modified virtually all those old instruments to modern playing standards.

    So, today's best instruments were made by the old methods, then later setup for modern playing.

    My approach to this to say 'revive' the old ways of making, but let setup belong to modern methods.

    In practice, what this means is that if you are making an instrument for Baroque setup, then just 'Do As They Did', all the way.

    But usually, you're making for a modern playing setup.  This requires some decisions in handling the neck and fingerboard elevation.  But I still want the sides and neck to get worked together in the old way. I want the instrument to go through those steps of twist aligning the neck on pins.  Then working the back outline geometry 'chasing' the actual sides and corner disposition. And then later independently working the top outline, again in relation to the real disposition of the sides, sides which in the old processes aren't necessarily square.

    To reconcile the old build and the new neck/fb, you attach the neck early, just when you would in a fully Baroque build.  But, you mortice the neck, and anticipate the neck angle as best as possible.  And you cut the neck back alla Lady Blunt so top can fit at the neck in the old ways.  The Baroque build, their wedge system allowed final fb angel setting. To get this needed opportunity with the Lady Blunt style neck, leave wood where the FB glues to be cut back later.

    It's not difficult.  Old build. New setup.

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