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Marty Kasprzyk

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Everything posted by Marty Kasprzyk

  1. The Italians have used bark tannins for (you guessed it) tanning leather since ancient times. Apparently different tree species have different color tannins which enables many different color leathers to be made. It's probable that when spruce trees were cut for violin top plates that the bark was saved for tannin production. Oak and chestnut tannin are used as preservative in wine making (Italy makes wine) and I tried a water solution of chestnut tannin to dye a curly maple strip. It then was given several coats of Birchwood True-Oil gunstock finish (Brescia Italy was a leader in gun production at the same time the violin was being invented) and the attached photo shows a center area which had the chestnut tannin dye applied. The outer areas were plain wood. The color was a light amber rather than a golden yellow. Maybe spruce bark or some other tree bark might give a more yellow color tannin.
  2. Strad had about 90 unsold violins when he died. I think I can do that too.
  3. Good question. I used Audacity's Hanning window of 256 for the plot I had shown. I'll try some others to see how the noise looks.
  4. One things different with real instrument sound is the presence of noise. Apparently some noise adds an element of "richness" to a bowed note. Attached is a fft of a bowed open string A note (440Hz) on one of my violins which shows noise between some of the upper harmonics. I suspect this rather high frequency noise is coming from random bow hair slipping or grabbing and that the bow-bow hair- rosin and bowing (force, speed, position) affect the amount of noise and where it occurs. I'm further guessing that amount of this noise is also dependent upon the height of the "bridge hill" in the violin's frequency response curve.
  5. That's already being done. A solid body electric violin accurately amplifies the string's natural vibration harmonics. A filter(equalizer) circuit can be added to change the harmonic's amplitudes to duplicate the sound of any acoustic violin. The people who are able to do this are "downright stupid".
  6. Does anybody have any ideas what causes this 'click effect' at the beginning of each note which some players seem to like?
  7. No, Anders said it correctly. At resonance you should use a higher minimum bow force
  8. The violin is slightly tipped in the photo. The back center joint is curved rather than straight and the heel isn't centered with the neck.
  9. Yes, that is correct. The carbon fibers should be on the outside surfaces to prevent bending to the front or back. I've made a very light balsa wood bridge that had the unidirectional carbon fiber tape on the outside surfaces with a vertical fiber direction. I thought it worked well but apparently the VSA judges didn't like it. The traditional maple bridges have the grain going in the horizontal direction with a low bending stiffness which is the worst way of avoiding bending in the front or back directions. There must be an acoustical reason for this choice that is more important than bridge deformation.
  10. I suggest adding a second sound post located below the bass side lower f hole eye to limit top plate motion in that area.
  11. Should the string spacing and arch shape of the tailpiece fret be the same as the bridge such that the after lengths of strings are parallel or is something else better?
  12. I got slightly a slightly higher 15.6 percent increase in string downward force on the bridge going from 161 to 158 degrees but I don't know if this increase affects the sound, or if it does affect the sound is it better or worse. But the advantage of a real low degree angle (acute) is that it puts a lot of force on the top plate which causes it to deform by creep and perhaps crack. This keeps violin restorers employed.
  13. I beg to differ. When I mathematically model the transient response of a forced harmonic vibration I find a high amount of damping gives a shorter transient time to achieve a steady state vibration at the start of bowing a note. After the bow is lifted off the strings the decay time is shortened with a high amount of damping. So if you are playing fast passages a lot of damping gives a crisp note sequence. Torrified wood with its low damping seems to be recently popular for guitar makers because it gives a long sustain (long ringing) for plucked notes which is greatly appreciated for guitar players. Maybe guitar makers and violin makers might have different wood preferences. A while ago Joseph Curtin had a chance to examine a top plate of a Strad violin. I think he said that when he tapped it it had a dull "thud" sound. This lack of ringing may indicate that this Strad top plate had a lot of damping. Perhaps other readers might give us Curtin's reference and his opinions.
  14. The suspense is killing me! What did you find out? I found that if you make the string angle near 180 degrees the strings can lift out of their bridge notches during heavy bowing and that the bridge tends to skate back and forth over the top plate nether of which sounds very good.
  15. I saw a good violin player demonstrate how a change in chin rest pressure changed the sound. He wasn't doing it to tame a wolf. But at the time I didn't have any way of recording this so I didn't have a chance to analyze the sound. The B0, B1- and B1+ modes have large bending motions of the entire violin so I suspect a variation in player holding force would change the sound around those low mode frequencies.
  16. I agree. I tried to play a C note on the A string with a piece of chisel pointed wood pushing down on the string and doing the same note with a finger tip. But a couldn't seem to bow the two conditions exactly the same so it is difficult to conclude anything about loudness or damping of the harmonics. A bowing machine would be helpful. But I did find the wood piece gave a much longer ring after the bow was lifted off of the string than the finger tip gave which shows the finger tip is adding damping.
  17. The played open string notes are louder than the same notes played on fingered strings. This means that the player's relatively soft finger tips must add considerable damping. Attached is a plot of one of my violins with the open E string being bowed compared to the same note fingered on the A string. The finger tip seems to add more damping on the higher harmonics. I've sometimes gotten the impression in blind tests that there was more sound difference between two different players playing the same violin than the same player playing two different violins. I used to attribute this to the different players having different bowing (bow speed, position, force) but now I suspect that the physical properties of the player's finger tips also plays a roll. We like to investigate the violin wood properties and violin design but maybe the player's finger tip properties are more important: finger tip diameter, flesh stiffness, skin callus thickness etc.
  18. Assuming a good way of measuring violin body damping is found--does anybody have an opinion on what level of damping is best?
  19. All of your plots and references convincingly show that the violin has poor output on its G string. The instrument historian Stewart Pollens (1) makes the case that the earliest violins made before 1550 had an A0 frequency of about 270Hz and used only three strings with a DAE tuning with the D string tuning of 293.7Hz. He mentioned that these early three-stringed violins were later converted to using four strings and all violins made since then were made with the same original size. He stated: "A three-string violin having its lowest pitched string fully supported by the violin body's air-resonance represents intelligent design. The addition of a string (G) whose pitch was below the air-resonance thus represented an acoustical compromise." Some good violins have higher A0 amplitudes than poorer ones but their A0 frequency is still too high. The A0 frequency is inversely proportional to the cavity volume of the instrument which suggests in general that the violin is simply too small to have a good output on the G string. I think the notes on a viola's G string sounded richer and more satisfying to me than on a violin's G string. Attached is a frequency response curve of one of my recent large violas strung with EADG strings which, by chance, happens to have an A0 frequency right on the 196Hz open G string. Also attached is a Saunders violin's band average plot which shows its strong low frequency output which is the opposite of traditional violins. So I agree with Pollens' comments and I think it might be possible with some increase in violin body size to get a really even output in the lower frequency bands which some people believe is desirable. I also agree with the opinion that there should be a steep high frequency fall off to prevent harshness and that a "bridge hill" around 3000Hz is desired. Stewart Pollens, "Thoughts on the Tuning of the Early Three-String Violin", The Galpin Society Journal, March 2011, Vol. 64(March 2011), pp.61-66, https://www.jstor.org/stable/23209390
  20. Marty Kasprzyk

    ......

    I think this looks like it was drawn with a compass with linked circle arcs with abrupt changes in curvature radius. It doesn't look natural or appealing to me. This may indicate that it was drawn by an engineer or draftsman rather than by an artist. On the other hand I've noticed a recent popular trend in restaurant interior design towards an industrial appearance--exposed air ducts, pipes, steel beams, straight back chairs etc. all having strong geometric lines.
  21. Saunders mentioned that good violins have strong output in the low ranges but your graph shows that his examples of good violins have a weak output in their low range (G string 196-349Hz notes). Maybe he should have said that good violins have a bad output in their low range but not as bad as really bad violins.
  22. Thanks for the information. I updated the graph and added your other researcher's frequency bands. Apparently all six of these investigators had different ideas on what the band widths should be and it would be interesting to know why they made their choices. Meinel's bands are simple musical fifths which have a 3/2 ratio of frequencies. For example 194 to 290 Hz band comes from 194 times 1.5 = 290 and so on. This coincides with the violin's string tuning pitches for the G,D,A, E strings.
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