Marty Kasprzyk

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About Marty Kasprzyk

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  • Birthday 06/02/45

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  • Location
    Olcott, NY, USA
  • Interests
    Wine making, gardening, dog training,
  1. Conforming f-hole templates to arching between c-bouts

    The viola study was done by the Oberlin makers group not the acoustics group. I'm anticipating they will find a lots and lots of scatter. Scatter in everything: listener preferences vs. player preferences, geometry and materials correlations with sound character and so on. In fact if you study this stuff hard enough you eventually become scatter brained.
  2. Violin geometry references

    I wrote an overly long explanation of violin drawing methods for Julian Crossman Cooke a few years ago and it is attached. After thinking about it more I concluded my varnish takes too long to dry and I need to find something faster. An alternative is to have several instruments being made at the same time with staggered operations. Bend_rib...pdf
  3. Conforming f-hole templates to arching between c-bouts

    A ridged cavity would indeed have a square root proportion. But the violin body is flexible and compliant so tests have shown the exponent is closer to one fourth power.
  4. Conforming f-hole templates to arching between c-bouts

    The A0 frequency is proportional to the f hole area A to about the one fourth power A^.25. The width distortion reduction might be around ten percent from a 3d projection to 2d so 0.9^.25 = 0.974 so your A0 frequency would be only 97.4% If your A0 goal was 280Hz you would end up with only 273Hz. I doubt any body could notice this difference. I've found you have to make a massive change in f hole widths to notice anything changing.
  5. Violin geometry references

    You might like the attached pdf of a 1909 reprint of the book "The Analysis of Beauty" by William Hogarth, 1753 My only complaint about the book is that I wish somebody would translate it from English into American. I have difficulty understanding foreign languages. analysisbeauty00hogagoog.pdf
  6. One Very Loud Note (A5)

    Try wedging a rubber eraser between the chin rest and the top plate to kill the plate's vibration in the lower bout. The brown ones look better than the pink ones.
  7. Violin geometry references

    Attached is another reference for drawing the violin's outline shape. I don't agree with Krupowicz's idea that the C bout shape was generated with the bent rib approach because the Strad's real C bout shape doesn't match a bend shape very well. I think the C bouts were generated by some other drawing technique (free hand, circle constructions etc.) I thought Krupowicz's use of math was interesting but it is easier just to bend a piece of maple rib stock. 056.pdf
  8. Downforce Experiment

    A small percentage of people have "perfect pitch" they're at the tail end of a bell curve of pitch discrimination ability. Is there a term for the people at the opposite tail end of the bell curve who can't tell one note from another like me? I would like to feel special too.
  9. Favorite small viola model?

    My first viola I made in 2001 was a Carleen Hutchins Alto and it had a body length of 20 in. (508mm) and weighed 990g without a chin rest or shoulder rest. It sounded wonderfully deep and rich but only a very few could play it under the chin. I found that viola players liked shorter and lighter weights much better so after many years of redesigns my last one was only 15 1/4in. (387mm) and weighed only 434g total with a chin rest and built-in shoulder rest. So my violas have been loosing on the average about 0.3 inch (7.6mm) and 35 g per year and after a several more decades they might completely disappear.
  10. Downforce Experiment

    A harp has a long sustain or ring from its plucked notes which is desirable and a reason why harps are used for some music. This happens because there is a large impedance mismatch between the relatively light strings and more massive soundboard. The strings only slowly transfer their vibration energy to the soundboard because most of the energy is reflected at the soundboard. If a harp string was somehow bowed it would have a long ring after the bow was lifted from the string. Quick note passages would sound like clarion bells and each note would lack clear ending definition (mush). If we add a bridge with an intermediate impedance between the string's and the soundboard's impedance the string's energy is more rapidly transmitted to the soundboard. As a consequence when a violin string is plucked the sustain is real short and quick bowed notes will sound crisp and clear. As Don pointed out the string break angle doesn't have much of an effect on the string energy transfer. Please excuse me for "harping" on this issue.
  11. Violin geometry references

    An excellent review of historic drawing techniques is the book "Creating Shapes in Civil and Naval Architecture (History of Science and Medicine Library)" edited by Horst Nowacki and Wolfgang Lefevre, 2009 I learned that wooden ships were often built with molds in order to exactly duplicate their shapes which is similar to violin makers using molds. I can't afford to buy this book (151$) but there are many long passages from the book which are posted on the web for reviews.
  12. Downforce Experiment

    A harp doesn't have a bridge and it still makes sound. I don't know what this means but I thought I'd say it anyway. I used to just bolt my necks onto the body. It was really convenient to try different body designs without having to make new necks and fingerboards each time. But I discovered that an instrument sounded better (more even and higher peak heights in the fft curves) if the neck was also glued in addition to being bolted on. Perhaps the guitar world has also found this out. I concluded that vibrations aren't transmitted very well across joint discontinuities. Encouraged by the good neck gluing results I started gluing on my bridges too and this also helps greatly. People have always claimed that good bridge fitting was important and perhaps gluing is an extension of this practice. Of course I only do this with my own instruments.
  13. Violin geometry references

    The binding of my old physics textbook finally fell off and bent by itself into a violin bout shape thus proving that the violin's geometry is based upon physics.
  14. Violin geometry references

    I discovered this was just an ordinary drafting divider and straight edge "Triangle" method for making a parabola. The attached PDF from the internet is a description of how it is done. If you do a Google search you will find lots of examples. In the past I've mentioned that a bent rib(spline), hanging chain (cantenary), and a parabola all seem to very closely match the shapes of the upper and lower bouts. I had originally used mathematical plots of Y = aX^2 to generate the the parabolas. The constant a could be adjusted to match the bout curvatures but I thought it was highly unlikely that wood craftsmen would know how to do this so I didn't think the bout shapes were originally done this way. However Thomas's MN topic "Geometric References" made me rethink this. The "Triangle" drafting method is very easy and quick. The angle and or the divider increments can be adjusted to give a wide variety of "pointedness" and I constructed a several paper drawings of them in 1 degree increments from 60 to 67 degrees and cut them out as patterns which I have used for designing my own instruments. That way I can join the group and say that I too use "geometric constructions". But I still think the violin rib's bend shape is made by bending ribs.
  15. Favorite small viola model?

    Straight oak wine barrel staves were traditionally bent by building a fire inside the barrel to get the wood hot enough to bend into shape. If you had simply cut the curved shape the longitudinal hollow cell walls would let the wine leak out. By bending the staves the hollow cells follow the barrel contour shape so the barrel can't leak. The fire inside the barrel toasts the wood's inside surface and the amount of this toasting has an effect on the wine taste and you can use barrels with various amounts of toast--light, medium, heavy. A more modern way of bending the barrel staves is to heat them with steam however the wine taste is different from using traditional fire bent staves. California Chardonnay was never considered as good as French ones until they started using traditionally made wine barrels. In any case, if you using your violas to store wine you might want to consider how you bend the tops.