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David Beard

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Posts posted by David Beard

  1. If the painters already have a language with a well-defined vocabulary, and in this instance, it seems to work, since it describes a situation involving varnish particularly well, is it really necessary that we steal their words, and give them new, different meanings, when the ones they already have are old, understood, and work? Having stolen their terms for how paints act when thin and thick and redefined them in an incompatible way, now you have to write a new term for something they've already explained and defined with their words.

    If that's how it's going to be, you can count me out. We need to build on what's already understood in other fields; we do not need to make ours different and incompatible by using old words in new ways that confuse anyone outside the field who already knows the way the words are defined in other fields.

    You picked a particularly good place to start the discussion with, I'll say that!

    Yes!! It's confusing to diverge from the general pigments and paints vocabulary when there isn't a need.

  2. I'm no expert, but it seems like the ideals of violins are somewhat parallel to wines.

    The ideals are substantially a set matter of established historical and cultural choice. If you acctually succeed in make a violin in some objective sense exceed the traditional standards, it would also start to be a different animal. The difference would likely be most often characterized in negative terms as a defect.

  3. Yes, the modulation frequency does not transfer energy. But the 'mother sines' does. That is a big difference.

    Again, this is a matter of choice of definition.

    You certainly acknowledge that the carrier waves transfer energy.

    If you now regard the carrier waves as only a medium, then the energy is being transfer by the resultant wave.

    The assignment of the transfer of energy to the carrier waves or to the resultant wave is definitional, not absolute. The combination DOES transfer energy.

  4. It is not an illusion in the ear.

    One could 'define' sound in terms of instantaneous pressure, in which case per definition the 'sound' is only the Fourier analysis sine waves. But this is not the only possibility, and it is a falsely continous and physically unreal but math ideal choice.

    However, since we aren't interested in idealized infinitely divisible mathematics but instead in physical phenomena, there is little or no reason to reduce the time slices below a phenomena appropriate percent of the wave length.

    If the observation is smeared or averaged out a bit, then we have to acknowledge that there really is a periodic variation in both presure and momentum of the medium. This really is sound. And it does all the same physical things.

    Most physical wave media are in fact ultimately granular or otherwise discontinuous and non-ideal in a math sense. The fact that these resultant waves are waves of waves instead of directly waves of the basic medium does not make them unreal. Fourier analysis is the unreal fantastically continuous falsehood, not the other way around.

  5. Fourier analysis is a mathematical thing that doesn't necessarily agree with our experience of sound.

    FFT should properly yield only the sine waves which add together to match the pressure pattern.

    But our experience of sound seems to be more related to the collection of ideal resonances the pressure pattern would be able stimulate, plus various ghost resonances to complete implied harmonic series.

    Sound then can be more complicated than the underlaying Fourier analysis might lead one to expect.

  6. Early in my violin acoustics career I also thought that these parts, top, back and the ribs were more or less idependant. But, at least in the 'modal model' of the violin, they do act as an unit. Possibly the air is somewhat less coupled to the body than the plates and the ribs. But I do not think the air and the body ever act independant, unless the plates are made immobile or are really heavily damped.

    I have a feeling that a filter can be as complex as you want (or do not want). I know some hate that description, but to me the violin body is an 'acoustic amplifier' in addition to the filtering property. (It may sound counterintuitive to call the body a n 'acoustic amplifier' when we know that much less sound energy comes out than we put in, but even an electrical amplifier and a loudspeaker system produces mostly heat, remember. Maybe somebody know the ballpark 'energy budget' numbers here?)

    Signal processing is not one of my main subjects. My mental models may well be insufficient or just not valid.

    Hi Anders,

    I'm still interested in the potential independence of these elements. Consider: demonstrating elements act in concert for particular frequencies and modes does not mean that those elements might not work independently for other modes or frequencies. Further, I'm as much or more interested in the other behaviors of the elements besides resonance. Elements can also have functions of transmission, radiance, and loss/resistance. Also, resonance isn't necessarily the whole story for the element's induction, impedance, and mass. I don’t see any way to exclude the possibility that an element might not work as a part of unified large/slow resonance while simultaneously working as a separate transmission element for some high frequencies.

    With the signal v noise business, I'm mostly interested in the potential for energy from the noise being fed into the signal. I don't see how to discount the possibility of signal amplification. I've noticed people concluding that a violin lacks a power source for amplification to be possible, but this is essentially incorrect. The noise component of the input through the bridge is a power source. It is possible that this power might feed the signal. Even a commercial bought amplifier overall loses energy. But we call it an amplifier because it takes non signal energy and feeds some of it into the signal.

  7. I'm not sure how wide spread the idea is, but at least some of the posts on this thread seem to accept a complex filter as a good model for violin behavior between the points of string input and radiated musical sound

    I'm reluctant to assume the violin is 'just a filter'.

    The plates, the main air mass, and the sides constitute at least three partially independent but connected/communicating systems each with sufficient mass to potentially lag or store sound energy. Further, we are mostly interested in the 'signal' energy that radiates from a violin, but the input from the strings and the energy within a played violin are both combinations of 'signal' and 'noise'.

    The interactions within a played violin might easily amount to something different then 'just filter' behavior.

  8. Good luck with that line of thought. I've been playing that tune here for years. To the science guys if you can't measure it, it doesn't exist and it doesn't matter.

    I would hope that market value is accepted as some sort of numerical measure of collective evaluation, reflective of the elusive qualities you cite?

  9. Hi LeMaster,

    The initial question in this thread had to do with moving the soundpost and not the role of strings (which is another story)... for me it's highly counterproductive to introduce even more variables into the equation while doing a soundpost adjustment. I prefer to do one aspect of the set-up at a time and then, only if deemed necessary, go back and repeat work on any other area of the overall set-up.

    I prefer to look carefully at the whole set-up even before I get the idea, or come to the conclusion, that the soundpost should be moved. For me its essential to have the other features of the set-up in the best possible condition before starting to move the post.

    For example, if Im moving a post around, new or old, in search of the best position, I wouldnt want to have to take the strings down again to change the after-length of the tailpiece, or adjust the string grooves in the bridge or the upper nut, nor remove wood from the bridge, smooth the fingerboard or any other job thats going to disturb my work on the soundpost.

    Bruce

    I take it then that the soundpost is the finally piece of the puzzle?

    Are there other esential points of sequence in the setup?

  10. Hi Ernie,

    I'm quite sympathetic to the problem, ...

    I'm thrilled to have the internet and Meastronet. ...

    I believe that the internet and Meastronet give more information then was ever available before to new learners. I feel priviledged to have the opertunity to interact with the likes of David Burgess, Bruce Carlson, Roger Hargrave, Michael Darnton, Jeffery Holmes, ... The people here are amazing. What school anywhere or anytime has given such generous opportunity for the beginner to dialog with the best with such frequency and depth?

    ...

    I guess what I'm trying to say is take courage. I don't believe anyone is trying to bar our way. There always are steps that are for the moment out of range and must wait. There always are steps that can be taken today.

  11. I was curious to see what a instrument would look like if it was to have a golden ground applied to all of the instrument with the exception of the top and bottom plate corners as well as not applying in the wear patterns on the back.I would like to get opinions .

    I suppose it might look like many of the very yellow/golden stringed instruments in early paintings.

    Oripment seems a likely component in at least some early grounds. As someone mentioned, arsenic shows up in some of the published info, and orpiment was used in the period. Cenini mentions both its danger and its beauty.

    post-30802-0-17985600-1314374733_thumb.jpg

  12. Hi All,

    It would be great to add a section on resonance terminology to Jeffrey's reference links.

    A0 B1+ M5 Transition Hill Bridge Hill Dunnwald Dip ???

    These things aren't always clearer to me.

    I'm probably not the only one who would benefit from a reference point for such terms.

  13. Looking back to the contributions of Don Noon and Ode, and trying to ignore the flame portions of this thread –

    Just considering the flow of energy through the bridge into the instrument, one might expect a sort of mechanical crossover sending different parts of the input into different physical reactions. I’ll venture a hypothesis, but of course it must yield to actual experimental and practical results:

    1) Some signal energy would twist or flutter the bridge table due to the off set of the treble bridge foot from the post position. (higher frequencies, small movements)

    2) Some signal energy would pump the bass bar side through the widely discussed bridge rocking movement (lower frequencies, larger movements)

    3) Some signal energy would pump through both feet against the balance between the string load and the push back by the deflected top and back linked through the post (??middle frequencies, medium movements??)

    4) Some non signal noise energy might potentially pass from the bow/strings into the instrument. This is interesting because of the outside possibility that noise energy in the instrument has at least the potential to be recycled as actual amplification of signal energy in the instrument. –not to say that such a mechanism of amplification from noise energy is actually present, but only that it is an interesting possibility.

    Even if these hypotheses are correct (a big if!), they only address the initial path of energy into the instrument. Many further things might happen between these initial responses and eventual radiation and dissipation of energy.

    But I believe these are some good ideas to start with.

  14. While I can understand the historical starting point, I'm curious why there is still so much focus just on resonance, and particular in the pitch of resonances as 'tap tones'.

    I'm no physicist. Yet just a little amateur sleuthing shows that physics has a well established parallel between wave theory and electrical theory. In both cases there is power, transmission, inductance, capacitance, resistance, etc. --though each tends toward distinct terminology.

    I don't understand why more research doesn't bring this full arsenal into the analysis? Focusing on resonance is like trying to explain an electrical circuit only in terms of capacitance.

    Also, any successful analysis would need to study at least all of: Energy as Sound compressions in the wood, Energy as Sound in the air inside and outside of the violin, Energy as non sound noise vibration in the wood (interesting because noise energy might in some cases convert back into energy supporting the driving sound), and energy as deflections of the wood (essentially a system of elastic springs and mass).

    There is a difference between transmitting sound through wood (press an inducer at one end of wood sample and capture at other) versus storing a vibration in deflections of the wood to transmit to air (bow or flex a bar of wood)

    Also, why don't we see more borrowing from speaker theory. That industry has a fairly developed understanding of its work, much of which relates.

    Further, the violin is a driven system with external power from the bow and external 'signal' from the strings. There are also very important effects of time. Energy builds, retains, and dissipates. None of these aspects can be omitted in a successful theory of the violin.

    I think all the pieces are out there to be used.

  15. The fact that it was such an established an multipurpose art ingredient in classical Italy makes me want to favor its use.

    Also, glair can be mixed with a small amount of oil to make it a bit less brittle.

  16. Still, for those of us who have a huge amount still to learn, Wikipedia provides a ready and fluid starting point to begin research on anything unfamiliar. Thanks to Wikipedia, I can wonder what a mention of 'butter of zinc' refers to and 10 seconds later I have a little orientation under my belt.

    I'd be a fool to consider the information final and absolute, but only fools have that kind of confidence in any source.

    For novices like myself who don't live right at the university library, or have any significant budget for special rare books, open and accessible sources like Wikipedia and Maestronet are a treasure.

    True gold nuggets like the PDFs posted on Roger's site are rare and hard to come by. Sometimes we must dine on lesser food.

    Respectfully,

    David

  17. I understand that the prevailing working idea is that black mastic is made from ebony dust and hide glue.

    Are there alternate theories for the Cremona and Brescia black mastic? Perhaps oil or resin based? Perhaps serving as the actual adhesive?

    I ask both because ebony seems to be more a late comer to violin making rather than an early material, and also because some pictures of mastic don't seem to look much like a hide glue based material.

    post-30802-0-61234500-1307992711_thumb.jpg

    post-30802-0-09750600-1307992881_thumb.jpg

    post-30802-0-59041700-1307992918_thumb.jpg

    Any thoughts?

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