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Marty Kasprzyk

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Posts posted by Marty Kasprzyk

  1. 5 hours ago, Bodacious Cowboy said:

    I think this is already well understood by those who know about these things. My (undoubtedly flawed) understanding is that the "force window" for clean Helmholtz motion of the bowed string is significantly smaller for a heavy string stopped at a high position. So it's more readily disrupted by the vibrational body mode responsible for the wolf tone. I guess someone like Marty will be able to give a more authoritative/rigorous explanation.

    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. On 6/17/2022 at 6:44 AM, HoGo said:

    OMG. After reading the paper I'd like to get the lab-rats to actually make instrument out of the wood to show something. I don't see any proof of anything in the paper. Just comparison of wood properties of samples from two logs. They somehow assume that higher density is better quality wood based upon citation of another paper. These guys pretend they know what makes great instrument but in reality they never made one or most of them don't even play. I know personally few folks from that university department and they are pure theoretics, they can measure wood samples properties, that's all.

    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. On 6/16/2022 at 8:47 AM, JacksonMaberry said:

    This is far less important historically than we tend to believe now. And many an excellent maker today doesn't care whether the maple is figured or not. Players, on the other hand, which aren't required to have a detailed knowledge of what makes wood suitable for making, tend to judge more on looks. 

    What do you think is suitable wood for back plates?

     

  4. 8 hours ago, nathan slobodkin said:

    Marty,

    > but my intuition tells me narrow flame is not always acoustically great while some plain wood is.
     

    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. 3 hours ago, Bodacious Cowboy said:

    Sure, but why?

    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.

    Screen Shot 2022-06-18 at 9.26.31 PM.png

  6. 1 hour ago, John_London said:

    Ida Haendel complains about the wolf on her 1696 Strad at 25:20 and 44:30 in this video https://www.youtube.com/watch?v=2fARPbGGbtE. She says that it appeared from nowhere. It is on the 3rd finger D on A string, not somewhere high on the G string. No wonder it drove her mad. If it appeared out of nowhere, it is perhaps not so much a feature of a fine instrument, as of a violin past its best?

    The luthier tries to fix it at at 47:20. He diagnoses by blowing into the bass F hole which gives a note around D, then holds the bottom and taps the scrolls and hears a B flat, and says these frequencies should be close and are too far apart.

     

    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. 3 hours ago, Anders Buen said:

    !+It may be worth trying a different chinrest. The Guarneri models attached over the tailpiece affect the B1+ mode to some extent, adding mass and thus reducing the amplitude of the B1+. The frequency may also move a bit. Then the wolf may move too

    I prefer light side mounted chinrests. 

    Lighter strings also reduces the driving force, and thus wolf. Maybe mainly the G string or both G and D. 

     

    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?

  8. 3 hours ago, HoGo said:

    I haven't heard from any respectable maker that they use curly maple because of acoustic reasons. Most of the makers actually never made violin(s) out of plain maple to compare... Most of old factory violins were made of curly maple and thay sound like they do, some better, some not so much.

    Natural figure in stump is result of the bend in the wood so the outside fibers necesarily "fold" as their path is shotrer. Visually this is very different from curly pattern. Curly trees are curly along large part of the trunk. In most extreme cases up into thicker branches. The curly pattern gets stronger as the tree grows. It's very likely genetic predisposition of extreme cambium growth. The stump or crotch areas have the curl combined with the natural deformities of wood.

    I think curly cracks cross-grain much easier than plain maple - rib bending of curly maple tells it clearly.

     

    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

  9. 1 hour ago, HoGo said:

    OMG. After reading the paper I'd like to get the lab-rats to actually make instrument out of the wood to show something. I don't see any proof of anything in the paper. Just comparison of wood properties of samples from two logs. They somehow assume that higher density is better quality wood based upon citation of another paper. These guys pretend they know what makes great instrument but in reality they never made one or most of them don't even play. I know personally few folks from that university department and they are pure theoretics, they can measure wood samples properties, that's all.

    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.

  10. 5 hours ago, nathan slobodkin said:

    Brian Derber’s book is the only one I have ever seen which I think could guide a beginner to make a decent first violin on their own. The C. and J. I have never seen but have heard good things about. The Weishaar is an interesting book on repair although some what dated. I would not recommend Strobel. Having said all that if you are going to be studying at a (good) violin making school you should learn their methods first before exploring alternate methods of doing things.

    What was wrong with Strobel?  For the difference in cost you could buy a few good tools and sharpening stones.

  11. 11 hours ago, JacksonMaberry said:

    This is far less important historically than we tend to believe now. And many an excellent maker today doesn't care whether the maple is figured or not. Players, on the other hand, which aren't required to have a detailed knowledge of what makes wood suitable for making, tend to judge more on looks. 

    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

     

  12. 2 minutes ago, JacksonMaberry said:

    Be that as it may, this was obviously unimportant to a lot of really excellent makers, as evidenced by great fiddles by then still in use that may as well have been made of fenceposts. 

    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. 

  13. 8 hours ago, JacksonMaberry said:

    This is far less important historically than we tend to believe now. And many an excellent maker today doesn't care whether the maple is figured or not. Players, on the other hand, which aren't required to have a detailed knowledge of what makes wood suitable for making, tend to judge more on looks. 

    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

  14. 7 hours ago, sospiri said:

     

    Only a true Master Craftsperson could achieve such attention to detail as to copy the original wolf to the point where an expert pair of ears couldn't tell the difference.

    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.

  15. 6 hours ago, David Burgess said:

    >

    While owners of older instruments may expect rather expensive routine maintenance, including periodic neck resets, it seems that owners of newer instruments do not, so I've put a lot of effort into trying to meet new owner's expectations.

    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).

     

  16. 10 hours ago, David Beard said:

    Not when a fixed frequency drives into the instrument!

    Violins are not marimbas.  Other than for research, we don't normal strike a violin to simply excite the resonances, the situation you described.

    Instead, we normally send or drive a collection relatively fixed frequencies into the instrument for the duration of a note.   If the instrument is to respond, it must set up into standing waves that match the driving signal.  These standing waves will match the signal, which in general will not usually match the natural resonances exactly.

    This is where lower Q in the natural resonances is valuable.  The higher the Q, the less the resonance will be able to bend and setup in a standing wave that is only near to the natural frequency but not an exact match.

    We don't normally talk of standing waves and Qs in the violin world, but it is in fact the relevant physics.   Maybe we should expand our habits?

    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

  17. On 6/8/2022 at 12:10 PM, David Beard said:

    I don't believe 'light as possible' applies to violins the same as speakers.

    Speakers don't aim 'hold' the signal energy in standing waves.   A speaker cone is slaved to it's driver, and aims ro radiate the energy directly and cleanly.

    For a violin, the energy sets up in standing waves, and then radiates.  Mass is an essential component of these standing waves.

    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.

  18. 4 hours ago, Davide Sora said:

    Normally not, as far as I know most use the mortised neck. But who knows, there is always some eccentric personality who tries different things, such as this unknown maker:D https://josephcurtinstudios.com/instruments/ultralight/

    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.

     

  19. On 6/7/2022 at 10:16 AM, Don Noon said:

    There are all kinds of speakers... cones, flat panel, electrostatic, plasma...  but my favorites are these:  the travelling bending wave type on the left, and the pulsating sphere (compression bending leaves?) on the right.  IMO, a violin is none of these, or perhaps a blend of them, but speakers and violins have very different goals in terms of sound and performance.  Trying to "improve" the violin by chasing extreme speaker concepts would make it less like a violin.  However, I'd like to see someone make a plasma violin.

    Speakers.jpg.13c162fb73f584ebb2fa787dd0094cce.jpg

    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.

     

  20. 20 minutes ago, Anders Buen said:

    A narrower bridge will normally give a worse wolf.

    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. 

     

  21. 10 hours ago, Mat Roop said:

    I guess when you have your nose to the grindstone and don't look up, you have a lot to learn!... True in my case.

    In my earlier comment I noted that all speakers that I am aware of, are cone shaped with the hollow pointing forward. Well that is not at all true... apparently the better ones costing $25000- 250000 are shaped quite different as in the you tube video. ...and sound far superior to the cone versions, and more like instruments.

    Here are a couple of links my audiophile son pointed me to...The first is really interesting reading but way over my pay scale.

    https://www.audiosciencereview.com/forum/index.php?threads/omnidirectional-loudspeakers-best-design-available.19024/


    https://www.youtube.com/watch?v=JLnSsE6GZAs

    Based on the comments in the science review link... I think the experiment I proposed is a lost cause and I will not be sacrificing an historic Markie "Usual" for a test!

    Interesting discussion and thanks everyone for their input... Cheers, Mat

     

     

     

    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.

  22. On 6/3/2022 at 5:27 PM, David Burgess said:

    I hope most of you watched the Oberlin Acoustics Online Seminar presentation today. Lots of the things which have come up in this thread were addressed and discussed. Sam Zygmuntowicz was the main presenter, but there was a lot of input from some other really successful makers, as well as from some highly respected fiddle acoustics researchers.

    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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