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Marty Kasprzyk

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Everything posted by Marty Kasprzyk

  1. Your explanation is fine. Professor Jim Woodhouse gave a video presentation on the wolf note for the Oberlin Acoustics Workshop last Summer :https://www.youtube.com/watch?v=gTaOtKuWAHA His presentation avoids any math stuff and is only about 45min long. The subsequent question and answer discussions are informative too. I should point out that Jim has also made instruments so he has a practical feel for the problems. If you want more math detail on the "force window" for Helmholtz motion I suggest section 9.3.1 of Woodhouse's online book: euphonics.org He has suggested an easy way of reducing the severity of a wolf note is to use a lighter tension string which reduces the minimum bow force needed.
  2. Attached is a good university study on using different woods for guitar backs. The wood choice doesn't seem to be very important for sound quality so you might as well pick something based upon its appearance. I'm not aware of a similar carefully done study on different woods used for violin backs. Guitar back plate wood.pdf
  3. What do you think is suitable wood for back plates?
  4. The Kudela and Kunstar shows the various acoustic properties wavy grain wood are on the average better than the plain grain wood. But there's quite a bit of scatter with some overlap in their populations. So It is true that some plain grain wood is better than some wavy grain wood and history has shown that some good violins have been made with plain wood and some poor violins have been made with wavy wood.
  5. The Catgut Acoustical Society's May 2001 issue of the CAS Journal "A Retrospective on Air and Wood Modes' has several articles describing why A0-B0 might be desirable for improving the playing qualities of a violin. Professor Jim Woodhouse wrote a peer reviewed paper on this which I have not read. Its abstract is attached.
  6. He's trying to match the violin's B0 body bending resonance frequency (his tapping of the scroll) with the A0 air resonance frequency (from blowing air across the f hole) by adding weight to the fingerboard.
  7. They do move around a lot. Apparently their territory is between about 130 to 2600 square kilometers.
  8. Sam's talk is now on youtube with the above site.
  9. Is it better to reduce the height of the B1+ peak or should we try to move its frequency so that it falls between notes rather than on top of a note. Or try to do both?
  10. Attached is an article which examines the occurrence of fiddle back maple wood in Europe and its economic importance. One of its references is : Harris, J. M., 1989: Spiral grain and wave phenomena in wood formation. Berlin, Springer-Verlag Berlin Heidelberg New York. I think it is interesting that spiral grain wood is not desired for violin plates but wavy grain is appreciated. From the tree's point of view both may offer some survival benefits. I'm guessing tree trunks with either of these have high hoop strengths which improves resistance to length wise splitting while also reducing bending stiffness of the tree trunk. But I don't want to purchase the Harris book to find out. Fiddle back maple in Slovenia.pdf
  11. The cited paper gives some acoustic reasons why wavy maple might be preferred over plain grain maple and it was mentioned that players often like the appearance of highly figured maple. In addition to those reasons we might ask why a maple tree has highly figured (non straight) grain in the first place. Highly figured wood always is present in the stump and the branch crotches of a tree where a root or branch goes off at an angle from the main trunk. The straight portion of the tree trunk usually has straight grain but is sometimes wavy. If you have ever split firewood you will know that straight grain is real easy to split and that the figured grain is much more difficult. So a tree uses this complicated grain pattern to better resist splitting in those areas that have complex stress patterns such as the stump and crotch areas. The tree naturally grows this way without much thinking to resist the bending from the weight of extended limbs and from wind loads. So if you want to better avoid cross grain cracking of your back plates it is helpful to use highly figured maple wood. Or use plywood.
  12. What was wrong with Strobel? For the difference in cost you could buy a few good tools and sharpening stones.
  13. I don't think you should group all players together as you implied. Some players will immediately play an instrument (in my case just a few seconds) to first see how it sounds and then when they are done will look closely at the construction and wood which might influence their final evaluation. On the other hand, some players will first carefully inspect the instrument which might bias their evaluation and then play it to see how it sounds. So there is at least two different groups of players. This is why I used to believe that double blind playing tests were best way of evaluating the sound character of violins because it completely eliminates the affect of appearance on their evaluations. But I eventually realized that even blind folded players immediately sensed something was not quite right when they picked one of mine up. Thanks, Abby Normal
  14. Maple isn't good for fenceposts because it rots too fast. I don't see any advantage of using plain maple other than its low cost.
  15. Good looking wavy figured maple wood is better than plain maple for the back plate because it has a lower elastic modulus E and higher density p which in turn produces a lower speed of sound c. The attached article explains why wavy wood works better besides looking better. maple wood.pdf
  16. Martin Schleske made a tonal copy of a 1729 Domenico Montagnana violin and I think I recall reading an article where an interviewed player said that Schleske accurately duplicated the sound of the original one and even duplicated its wolf note.
  17. Whenever something fails over and over again in the same way it means the original design/material choice is no ____ing good (unless you business is a repair shop).
  18. I always recommend the book:"Why You Hear What You Hear- An Experimental Approach to Sound Music and Psychoacoustics" by Eric Heller. It gives a good explanation of how a violin works without using lot of math. If you want more detail I suggest Jim Woodhouse's web site: https://euphonics.org Attached is list of some of the reference books I have but some of them don't resonate with violin makers. Sharp tools are more important. Reference Books.pdf
  19. The term "standing waves" is not commonly used in descriptions of violin vibrations by researchers. "Nodes" (areas of no movement) and "antinodes" (where maximum motion occurs) are usually used in literature to describe the vibration modes (A0, B1-, B1+ etc.) patterns of violins which are often shown in laser scans of real violins or finite element simulations. These standing waves or antinodes happen because a bending traveling wave moving outward from a vibrating source point hits a boundary (like a plate edge/rib joint) and is reflected back inwards towards the original source (like a bridge foot). If the inward reflective bending traveling wave along a plate is in the same phase as the starting outward wave then they add their amplitudes together and a large unmoving antinode (standing wave) is formed which is called a resonance mode. If the out going and reflected in going waves are in opposite phase then their amplitudes cancel and no motion results which is a node. (it's easy to get confused between nodes and modes) It can be easily shown that the frequency of the resonance modes or standing waves is simply dependent upon speed of the bending traveling wave cl and the total distance 2L it has to travel out and back from a reflection. to be continued... Ahh skip all the rest: A light body with a low stiffness and low mass can give the same mode frequency one with a high stiffness and a high mass. The low mass one will vibrate more and produce a louder sound than a high mass one but if the mass is too low the vibrations become too large which screws up the string/bridge motion which produces weird or wolf notes as Don points out.
  20. If threaded steel machine bolts and nuts had been available 500 years ago the violin's neck attachment might have been quite different and Curtin's design would now be traditional.
  21. There's some similarities and differences between violins and speakers. Both use a moving body as light as possible to generate a loud sound without falling apart. The violin distorts the bowed string's saw tooth vibration input by having lots of strong resonances and its frequency response curve has lots of peaks and valleys which gives a violin its character. A Speaker on the other hand is designed eliminate any resonances in a frequency range so its frequency response curves is as flat as possible. So a speaker is supposed to give an undistorted reproduction of the distorted string sound of a violin.
  22. That's what I found too. The bridge acts as a lever which converts the sideways motion from the string's vibration to a vertical motion of the bridge foot. The ratio of the bridge height to the bridge foot width determines the multiplier effect of the string's force. A narrower bridge increases the bridge foot force on violin top plate which worsens a wolf. And a wider foot spacing helps reduce a wolf. But the effect is small. Another small helpful thing is to use a lower tension string. Adding a few of these small things together can make a wolf note more manageable. Good players take pride in being able to control wolf notes so you don't want to completely eliminate them because they become real frustrated when they can't find a wolf note to show off their skill. It's sort of a sick amusement for me to watch them searching in vain for wolf notes.
  23. If you are willing to be influenced by audio speaker designs I suggest you do a Google search on "flat panel speakers". One take away is that the panel should be very light and stiff.
  24. I was impressed with his systematic data entered on a spread sheet for all his instruments in chronological order. And his efforts to see if patterns or trends were emerging on works better or worse. Nice interplay of objective numerical physical measurements with subjective impressions.
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