Marty Kasprzyk

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About Marty Kasprzyk

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    Enthusiast
  • Birthday 06/02/1945

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  • Gender
    Male
  • Location
    Olcott, NY, USA
  • Interests
    Wine making, gardening, dog training,

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  1. Marty Kasprzyk

    slab cut - wide grain front

    Tops naturally come out made with the annual ringed closely perpendicular to the surfaces as a consequence of the wedge splitting and the length to width proportions of the violin were established long ago for the resulting longitudinal to cross grain elastic modulus ratio. If you wanted to keep the same sound character by keeping the same mode frequencies with off angle (45 degree example) low cross wise stiffness wood made by sawing it would be necessary to use narrower width bouts. While that might be able to work acoustically nobody would accept the skinny appearance hence it's not used. The opposite problem exists for plywood which has little stiffness difference in different directions. In this case the instruments should be made with wider proportions. But nobody likes a fat belly. Projection is important for violas too so you do want to have a long flight path.
  2. Marty Kasprzyk

    slab cut - wide grain front

    You could have used cross grain low stiffness for small violas where it might be beneficial to have low mode frequencies which are normally only seen on large ones. Model airplane gliders are similar to violas where you want a long time aloft before hitting the ground.
  3. Marty Kasprzyk

    An experimental pegbox and nut

    Now if the string is too long and bunches up against the peg box it will put an outward force on the peg which may cause it to loosen and slip. Be sure to cut your strings short enough to avoid this problem. Your original way of putting the string on the end opposite the handle was better (although confusing at first for a player) because a bunched up string would force the peg to become tighter.
  4. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    The Bissinger graph I presented was done with a stiff welded sheet aluminum body of violin size and shape ("La Empierre" in his references). The volume was changed by filling it up with various amounts of water. A real wood violin would be more flexible and would have the normal A0 frequency (~270Hz) however it apparently didn't seem like a good idea perhaps because of the hide glue. In any case, one interesting experiment was to add 200cc of water and hold the aluminum violin vertically with the lower bout at the bottom so the water leveled up there, then the experiment was reversed with the upper bout face downward, and then the experiment was repeated again with the body held horizontally (similar to using a low rib height). In each of the three cases the volume V remained constant (same amount of water fill) and the f hole area A wasn't changed yet the A0 frequency did change a lot---308, 329, 310Hz respectively. The classic Rayleigh equation predicts the A0 should have remained constant because the volume and the f hole area didn't change and their A/V ratio obviously stayed the same. Since the A0 frequency did change it meant that the Rayleigh equation (A/V)^0.5 was not correct for violin shaped cavities. The shape of the cavity has an affect not just its volume. But your point is still very correct--it take a huge change in f hole area or body volume to make much of a change. Tomorrow I'll take some photos of two of my experimental violas with greatly different f hole areas which proved to me that reading about other people's experiments was quicker and cheaper than doing my own. On the other hand "ignorance is bliss".
  5. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    Bissinger's graph shows the coupling effect of the upper and lower bout volumes and it was done with rigid walls of a full size body. Increasing the body stiffness or rigidity (decreasing the compliance) increases the A0 frequency. The A0 frequency increases about 10% when you insert the sound post which stiffens the body. Making the ribs thin and plates thin reduces it back down. There have been experiments with encasing the entire violin body in plaster to make it rigid to see how stiffness changes the A0 frequency.
  6. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    I very much agree that you have to make huge changes in the f hole area or violin volume to see an affect on the A0 frequency but I don't fully understand what affects the A0 amplitude. There are several reasons why the A0 frequency doesn't follow the classical Rayleigh square root of 1/volume. or 0.5 exponent. Rayleigh's equations are for rigid cavity walls whereas the violin walls have some compliance. Rayleigh's assumptions also used a simple shape (a bottle is a typical example used in experimental work where you fill it up with different levels to change the volume). The violin cavity on the other hand can be modeled as two cavities (upper and lower bouts) joined by a narrow portion (C bout). The longitudinal A1 air mode is influenced by the relative volumes of these two cavities. Since A1 is coupled with A0 the shape of the violin cavity has an affect in addition to its simple volume. George Bissinger has done many A0 experiments and he's shown the A0 frequency closely follows a 1/volume exponent of 0.25 and an exponent of 0.27 is even better. Attached is one of his experimental plots. The classic rigid cavity exponent of 0.5 is a poor fit for violin shape cavities which is shown with the blue line. 1. G. Bissinger, "Acoustic normal modes below 4 kHz for a rigid, closed violin-shaped cavity", J. Acoust. Soc. Am.100, 1835-1840 (1996). 5. G. Bissinger, ‘‘Semiempirical relationships for A0 and A1 cavity mode frequencies for bowed string instruments of the violin, viola and cello family,’’ Catgut Acoust. Soc. J. 2 (1), (Series II), 8–12 (1992). 8. G. Bissinger, ‘‘The effect of violin cavity volume (height) changes on the cavity modes below 2 kHz,’’ Catgut Acoust. Soc. J. 2(#2) Series II, 18–21 (1992). 11. G. Bissinger, “ Effect of f-hole shape, area, and position on violin cavity modes below 2 kHz” Catgut Acoustical Soc. J. vol 2, #2, 12-17(1992) 15. G. Bissinger, "Wall compliance and violin cavity modes", J. Acoust. Soc. Am. 113,
  7. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    The A0 frequency for a violin shaped cavity is more closely proportional to (1/V)^0.25 instead of the square root, (1/V)^0.5
  8. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    I try to follow standard string length, spacing, height over the fingerboard, bridge curvature, fingerboard curvature, neck length etc. that affect the player's fingering and bowing interactions. But all the other construction details (geometry and woods used) are completely different from Strad's or any other Old Italian instruments because we already know those designs are perfect so there's no sense in beating a dead horse. I do however meet the requirement that the instrument cases fit in the overhead bins of airplanes.
  9. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    Hi Andreas, Yes, all these data points are from my experimental light violas and violins. No. 22 violin had rich and loud low notes due to its low A0 frequency which I and many others liked however others thought it sound too different from a normal violin. My later experiments were attempts to get closer to normal violins. I often use an old fashioned Saunders loudness test to compare my violins. This test measures the loudness of each bowed note of a chromatic scale. I use Audacity for recording the notes and for measuring their loudness and I plot the results in Excel. The attached graph shows how No. 22 compares with No. 29. I've also included on the graph the average of 5 Strad violins measured by Fredric Saunders about 60 years ago. The vertical loudness scale in dB was fudged so that Saunders' amplitudes and mine are similar so the loudness is arbitrary and my loudness measurements can't be compared with his. But the important information is the overall shape of the plots. No. 22 had very strong low notes and weak high ones compared the Strad average which was pretty much the opposite--weak low notes and strong high ones. No. 29 was closer to the Strad ave. I should point out that my No. 22 and No. 29 plots look quite jagged. Individual Strad violins are also quite jagged but when you average 5 of them together the envelope looks smoother. It is my belief that you should try to minimize the loudness difference between the notes to make it easier for the player to adjust his bowing--you don't want to have overly strong or weak notes. My last just completed violin, No. 31 was played for the first time today by a good player. He said "it sounded like a violin" which was a novelty for me.
  10. Marty Kasprzyk

    An experimental pegbox and nut

    It,s much stronger than a usual hollow peg box. The only negative thing I can imagine is that the pegs directions are reversed--it might take a player a little time to get used to them.
  11. Marty Kasprzyk

    What does a (too) high air mode do to the sound of a violin?

    If your starting volume is 2000cm^3 with a 30mm rib height I estimate with a 20mm rib height the new volume will be about 1550cm^3. From George Bissinger's violin volume experiments (I'll provide references in a day or two) this should produce about 20Hz increase in the A0 frequency. If your starting frequency was a rather typical 270Hz ( C is 261.6 and C# is 277.2 like Don mentioned) then the new A0 frequency would be 290Hz which is near an open D note at 293.7Hz which is a just a little higher. Some people might like the higher A0 frequency while others might not. But as Don often points out changes often aren't generally well accepted. If you want to keep the original low A0 frequency with a lower rib height it will be necessary to decrease your f hole area. There are equations which predict what the new f hole size should be which brings up and interesting question: What works better- a large violin cavity volume with big f holes or a smaller cavity with smaller f holes? I've been able to argue both ways which is an indication of mental disorders (Gollum in Lord of the Rings) Another variable affecting the A0 frequency is the flexibility of the cavity walls (ribs and plates) with stiff walls increasing the frequency. Since my instruments are constructed so differently from traditional ones I try to adjust the A0 frequency from one experimental instrument to the next to get close to typical frequencies. So I play with these above variables all the time. Attached is a graph showing how the A0 of my last 5 violins and 6 violas has been adjusted trying to converge on typical 270Hz and 220Hz frequencies respectively.
  12. Marty Kasprzyk

    Stainer-old wood

    What do real Stainers sound like?
  13. Marty Kasprzyk

    Another 5 string Sultana

    I screwed up. I should have said "Why are you making these changes in those directions?"
  14. Marty Kasprzyk

    Another 5 string Sultana

    Why are you making these changes?
  15. Marty Kasprzyk

    British Amateur violin 1938

    Along the same lines I've often thought if one sound post is really helpful-why not try several more. How would we know if one bass bar and one sound post were optimum unless we tried more?