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Marty Kasprzyk

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Everything posted by Marty Kasprzyk

  1. It's sometimes difficult to compare the results of violin researchers because they break up the frequency response curve into different bands of frequency. Attached is a summary of Saunders, Duennwald, and Joseph Curtin band frequencies. Do you have the bands for Lottermoser and Meinel?
  2. But Saunders never explains why the Strad violins were made to have such weak response on their G strings which was shown in his loudness curves. If an even distribution of strength among all ranges of frequency was desired then you could conclude Strad violins weren't very good. It should be good to strengthen the output of the G string to make it more even. But then it wouldn't sound like a Strad which would be a bad thing to do. So as George Orwell said "Weakness is strength", and it follows in violin making that good is bad and bad is good.
  3. I made a Western red cedar replacement top for a beat up old cheap German violin and it sounded very nice. Somebody might reply that they made a cedar top too but that their results weren't good so they recommend not using cedar. I might respond by saying that I made a top with spruce wood and the results weren't good so I recommend not using spruce.
  4. Attached are two examples of a 3-D view of the violin's note harmonics (1 to 10) and note frequencies (piano keyboard representation) on the horizontal plane and the amplitudes in the vertical direction which shows the peaks and valleys. Ted White called this type of illustration a "mountains near a sea shore". It was taken from: A. Langhoff, "Measurement of Acoustic Violin spectra and their Interpretation using a 3D Representation", ACUSTICA, Vol. 80 (1994)
  5. Maybe the people who make cigar box violins are doing it because cedar is naturally bug resistant.
  6. I recommend you use serial numbers on your violins. Start with something like 247.
  7. Use expensive wood--it will make you much more careful.
  8. Another criticism of a book from someone who hasn't read it. The book is just a literature review of all sound post studies done up until 2017. McLennan's hearing ability is irrelevant.
  9. Apparently the Amazon book reviewer didn't actually read the book. It is well known that tiny soundpost position adjustments can change the sound heard by the player. Some players are so sensitive they can hear a sound change when the soundpost isn't even moved.
  10. You're right. The soundest prevents its side of the top plate from vibrating much thereby reducing out of phase far field sound cancellations. The sound post increases the sound output. If you like a more detailed explanation I recommend John McLennan's 2017 book "The Soundest in the Violin" I've never met him but he's an inspiration to me now that I'm getting older. He got his PhD at the age of 84 (!) with his thesis "Violin Acoustics from Baroque style to Romantic style instruments". He along with Oliver Rogers. Norman Pickering and Carleen Hutchins have shown that actively doing violin research increases your life span.
  11. Most of the violin's low frequency sounds (<1000Hz) come from internal cavity volume changes which cause sound to come through the f holes whereas the high frequency sounds come directly off of the outside surfaces. So I try to think both inside the box and outside the box.
  12. Plate arching doesn't seem to be necessary to have a steep drop-off . The size of a plate's vibration nodes decrease with increasing frequency so the arching of the span they cover decreases and it approaches a flat plate. This is even more apparent at the plate edges where the arching is already nearly flat. Attached is a frequency response curve of one of my flat top plate violas which shows a similar dB/octave drop-off. The frequency of the start of the drop-off is dependent upon the thickness of my plates--thicker:higher frequency. This might show that the thickness near the plate edges of traditionally arched plate violins is also important in determining the drop-off frequency.
  13. I would be willing to bet that an Audacity plot of a full orchestra playing would have a very similar high frequency fall-off
  14. The impact hammer impulse is dependent upon the hammer tip hardness--a soft tip hammer bridge impact will produce a violin frequency response curve with a rolloff at a lower frequency than a hard one. So you don't know how much the violin's frequency response curve is affected by the impact hammer's tip hardness. The violin's FRC is also dependent upon the direction of the hammer impact on the bridge-- a vertical impact will produce higher amplitudes at high frequency than a horizontal impact. Many researchers now do both (averaged ?) to better represent the bowing angle on the strings. I therefore use repeated bowed glissandos on the outer E and G strings for a violin with my computer's microphone and Audacity software. I think this is a more realistic violin test but it has the disadvantage of having poor repeatability of the amplitudes of the frequency response curve because my bowing (force, speed, distance from the bridge) is inconsistent despite efforts to control it. As a result I can reliably see the overall shape of the FRC and can determine the frequencies of the various peaks but their amplitude measurements is questionable. So if I make violin construction changes I can't reliably know if the violin's loudness changes. I should buy one of Curtin's rigs.
  15. The rain drops seem like really good way getting a broad band force into the plate. But if the area size of the plate increases it appears that the total force applied to the plate also increases. So if large plate produces more sound than a small one it might be due to a large plate being inherently a better sound producer or it might be simply due to more rain hitting it. On the other hand your impact analysis might use the same impact force on both a small plate and a large one so the difference could only be due to the plate size difference. Anyway I still think your program could be great way of comparing the effects of different wood properties, plate thickness and size.
  16. The high frequency fall-off above about 3000Hz is desirable and most other orchestra instruments are designed to do this too. Perhaps another topic heading should be : "How does a violin not produce high frequency overtones?"
  17. Professional players also sometimes have this problem too and it is helpful to have a violin capable of being played quietly.
  18. Do the rain drops hit the entire surface of the plate? Where on the plate does the impact hit when doing the impact simulation? Center, off center etc. This might be similar to a bridge impact test on a violin.
  19. It has been known for a long time that high arches and thick plates suppress the lower end of the violin's frequency response curve. This gives the impression that the violin sounds bright. Flat and low arched plates and thin plates have a similar amounts of high end sound but since the lower end has higher amplitudes the violin sounds deeper and louder. Attached are some graphs showing these effects from George Bissinger's 2019 VSA Papers translation of Hermann Meinel's 1937 study which is also attached. This works suggests two other combinations should have been studied: High arched thin plates, and low arched thick plates. What is finally selected is a matter of personal taste regarding the low end/high end balance. Bissinger's Tran. of Meinel .pdf
  20. The famous Kon-Tiki expedition used balsa wood rafts to float across the Pacific ocean without sinking. Perhaps this might have floated the idea of using balsa wood for the boat maker Doug Martin to use balsa wood for his experimental violins. But I think this sinking issue is more important for violas.
  21. Hi Anders, I'm normally always confused but now I'm abnormally confused. To increase the sound loudness for your panels should the cross grain stiffness be high or low?
  22. Thanks Anders for your new comparisons. Your program seems to be the ultimate "what if ?" You can change only one variable at a time which is very difficult to do with real violin constructions. My impression is that the critical frequency of the plate determines the peak's frequency and loudness is determined by the plate's mass per unit area. The mass per unit area is simply the material's density times the plate thickness. This helps explain why some thick skulled (bone has high density) people don't respond well whereas thin skinned people (skin has low density) are overly sensitive.
  23. Long ago Carleen brought attention to the plate mode frequencies F and she also noticed that plate weights M should not be heavy. Evan Davis more recently combined the two to measure plate impedance Z= (FM)^.5. The very carefully done Bilbao project has evaluated different combinations of top plates and back plates having different impedances to determine what listeners and players prefer. https://www.bele.es/en/making-tops-backs/ taptones_vsapapers.pdf EB Davis Contemporary Traditional Violin April 20 2010.pdf
  24. Wow what a fun thing to play with! I'm really envious. If you used a thinner maple back with a thickness of about 2mm it would produce the same Kg/meter squared surface mass as the 2.6mm thick spruce sample (1.2Kg/meter squared). I predict from your graph that the thinner maple back would produce more rain sound output than the 2.6mm thick spruce top example. This indicates that the violin has mistakenly been made upside down for the last 400 years. The top should be maple and the back spruce. On the other hand maybe this only applies for violas used in the rain. Something isn't quite right with my thinking. A low critical frequency is supposed to improve sound production efficiency and the spruce sample is clearly better than the maple one (your 500Hz was a misprint, it should be 5022). This should give a better sound output for the spruce. But I just got done predicting above that the thinner maple wood with an even higher critical frequency be better if the panels weighed the same. One of me is wrong.
  25. That's an interesting question. Suppose we accept the idea that a vibration variation in air pressure is what causes sound it then follows that in order to produce a loud sound we should have a large variation in sound pressure. Since the air pressure in a container is inversely proportional to its volume it follows that a proportional change in air pressure (deltaP/P) follows proportional change volume (delta V/V). Assume the change in volume (delta V) is equal to surface area of the top plate A times the amount that it deflects d. This suggests that the plate should be large in area and highly flexible. And the rib height should be shallow to have a small violin cavity volume. A large instrument with shallow ribs might be louder than a smaller instrument with deep ribs.
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