Marty Kasprzyk

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Everything posted by Marty Kasprzyk

  1. Marty Kasprzyk

    The importance of varnish

    That all makes sense to me. I'm just suggesting the fine filler particles shouldn't have a high density to reduce plate weight gains so it doesn't have much acoustic affect. If colophony rosin (density of only 1.03g/cc) powder was first rubbed on the wood surface it would fill the pores and prevent subsequent deep varnish penetration. Colophony rosin has an index of refraction of 1.541 which is probably similar to various oil-rosin varnishes so it might not have any negative optical effects. Rosin powder is inexpensive and commercially available.
  2. Marty Kasprzyk

    Houshold LED lights than don't strobe? Does anybody know of any?

    A DC power supply would be more convenient than a battery. If it had adjustable voltage you could adjust the color temperature and spectrum.
  3. Marty Kasprzyk

    The importance of varnish

    One of the justifications claimed for using a ground layer is that it reduces the amount of varnish that would fill up the wood pores. The density of mineral fillers is probably in the range of about 2.5 to 5 g/cc depending on what kind of ground up rocks you're using. The density of various organic materials and hardened varnish is around 1.1 to 1.2 g/cc. So a mineral ground would probably add a lot more weight and change the various vibration mode frequencies and amplitudes a lot more than simply using a pure organic ground-varnish system. I don't see any acoustic advantage of using a mineral ground.
  4. Marty Kasprzyk

    Houshold LED lights than don't strobe? Does anybody know of any?

    Would an old fashioned incandescent bulb with a rechargeable battery (old car headlight) give reduced flicker?
  5. Marty Kasprzyk

    String tension and afterlength

    The pitch (f) of a string is dependent upon the string's length (L) from the nut to bridge, the tension of the string (T) and the string's mass per unit length (m) with the following "Mersenne equation": f =(1/2L)( T/m)^0.5 The pitch of the string's after length follows the same equation. The tension T and the mass per unit length m stay the same so the pitch is higher due to the afterlength's shorter length.
  6. Marty Kasprzyk

    String tension and afterlength

    No. The tension at a given pitch is independent of the afterlength.
  7. Marty Kasprzyk

    Houshold LED lights than don't strobe? Does anybody know of any?

    When I do an Audacity fft test on my iMac with its internal microphone I always get 60 and 120Hz spikes.
  8. Marty Kasprzyk

    The importance of varnish

    You nailed it! It took me about 15 years to realize when somebody said my instrument was "nice sounding" it was actually a bad insult but also a graceful exit for the player. Now I specialize in making terrible sounding instruments. Players love them because then they can show off all their amazing skill.
  9. Marty Kasprzyk

    Tailpiece Grain Direction?

    Should the curvature of the tailpiece also match the curvature of the bridge?
  10. Marty Kasprzyk

    Planetary geared pegs

    I have one (1) Wittner cello peg you can have free. That should bring the cost down. I use Wittner pegs on all my violins and violas and like them a lot. However some good players (Nathan Giem, one of the VSA tone judges for example) don't like them because their pitch adjustment movement is too fine. It's amusing to see players reach for the tailpiece string adjusters and not find them.
  11. Marty Kasprzyk

    The importance of varnish

    Martin Schelske's work on how various ground and varnish systems affected the wood's speed of sound and damping loss factor was very carefully done and thorough but I think he didn't emphasize some of his results enough (see page 39 "level difference"). If you look at his figure 7b you will see that the admittance (related to how loud an instrument might be) decreased with one of his varnish methods. An overall decrease of 2.6 dB up to 1500Hz is a lot of lost output. Consider his sandarac varnish in Figure 3. It increases the speed of sound only about 1% and doesn't change the damping at all. You might conclude that using this varnish wouldn't change anything. However the speed of sound c is dependent upon the square root of the elastic modulus divided by the density. Since the varnish coating is very thin the thickness of his test bars is essential unchanged so the speed of sound for his samples is proportional to the square root of the ratio of the sample stiffness S to its mass M: c = (S/M)^ 0.5 So if you increase the test bar's stiffness and weight nothing happens to the speed of sound and all the various mode frequencies and sound character should stay the same. You might say this varnish is rather benign. However if you increase the stiffness and also increase the mass the impedance i or resistance to movement (reciprocal of admittance) also increases proportionately to the square root of their product: i ~ (SM)^0.5 So adding a lot of varnish can reduce the violin's output even though the sound character might not change. Please notice that the output is decreased with the stiffer heavier example even though the damping didn't change any. Quite often we blame a decrease in output is due to an increase in damping when in fact an increase in stiffness and mass is the culprit. So the advice to use a minimum amount of varnish is still correct but some times for different reasons. Schleske did this excellent work 20 years ago and it has been bugging me ever since. I haven't talked about it all this while. Maybe I should also say some things to my ex-wife.
  12. Marty Kasprzyk

    The importance of varnish

    I think the microphones are too close. If you were hearing this seated in the hall it would sound more mellow.
  13. Marty Kasprzyk

    shop lights.

    Maybe violins look best and sound best in candle light. Other things are better too.
  14. Marty Kasprzyk

    The Title for this item made me laugh!

    I had always thought that "points" were the sticky-out projections on "corners". So you can have a cornerless violin or a pointless violin with corners. They are not the same.
  15. Marty Kasprzyk

    Violin Bridges Can Be Confusing!

    They would get a better sound if they cut in some string notches.
  16. Marty Kasprzyk

    Houshold LED lights than don't strobe? Does anybody know of any?

    My iMac desktop has a screen color time control. Apparently yellow light is more restful so you can set it so the evening is has a yellow cast to make getting to sleepi easier. It automatically reverts back to a blue cast in the morning to help overcome hang overs.
  17. Marty Kasprzyk

    Boxy, honky nasal sound.

    Some of the English words sound like the sound they are describing. Since the title of the original topic was "boxy, honky, nasal sound" to describe a not so nice sounding violin I compared my spoken sound spectrum of "boxy, honky, nasal" words with the sound spectrum of more pleasant descriptor words "smooth, sweet, mellow". The attached frequency response curve shows that "boxy, honky, nasal" is more intense in the middle range 700 -1700Hz while being lower in the low range 120-600Hz and the high range above 1800Hz. So if you want a "smooth, sweet, mellow" violin sound then you show have good output in the low end and high end (bridge hill) and low in the middle (nasal region) like people often say. The "chocolaty" sound some people use for describing violins seems to be dependent on the percent cocoa in the the chocolate and this might be another one of those a personal taste preferences. At this moment I'm sampling Lindt 85% coca Extra Dark which has a "Full-bodied cocoa flavor". "Full-bodied" is good for violins too but I better wrap this up soon because its 230 calories for four of these little squares.
  18. Marty Kasprzyk

    Violin directionality

    When there is a vacancy in an orchestra to be filled and they audition players, do they use different music for 1st string and 2nd string openings? My impression is that it is so competitive nowadays that anybody selected can play either position. Is that correct?
  19. Marty Kasprzyk

    Boxy, honky nasal sound.

    I'm always serious--sort of. I think you get a" boxy" sound with a violin box which is too stiff. A "tubby" sound is the opposite and you get that with a violin tub that is too floppy. There's a continuum in between with good sounding violins strong enough to survive with good care. There are three difficulties with the above statements. The world violin community needs a commonly accepted vocabulary to describe sounds. These sounds should then be correlated with some measurable acoustic feature (fundamental's strength, spectrum centroid, number and strength of harmonics and so on). These acoustic features then have to be related to the violin's physical construction (all the stuff we talk about--arches, thickness, wood, etc).
  20. Marty Kasprzyk

    Boxy, honky nasal sound.

    A "boxy" sound happens when the violin is built sturdy enough to avoid the aging creep distortion, neck dropping, top sinking etc.
  21. Marty Kasprzyk

    Boxy, honky nasal sound.

    Two things not discussed are the use of steel core strings and lack of humidity control may worsen the distortion problems. I had a large viola set up in tune with steel core strings in the winter (Western NY) and left it untouched over the following summer. An increase in humidity caused the viola body to expand lengthwise but the steel strings were not very stretchable and their tension therefore must have increased greatly. The neck pulled up, the upper block rotated forward, fingerboard dropped, bridge area sunk, cracks developed next to the saddle. It was a really impressive mess so now I put steel core strings on all my violas.
  22. Marty Kasprzyk

    Boxy, honky nasal sound.

    I hope by now readers can see how the string tension can impose several different kinds of stresses the neck joint and plates. I further hope readers can see the implications of using a shallow sting angle over the bridge (high nut and high saddle) which reduces the downward load on the top and by not attaching the string to an end pin-compression loading of the top causing it to buckle and bend, and tension loading of the back causing it to stretch are avoided. I even further hope readers can see the implications of not having adult supervision.
  23. Marty Kasprzyk

    Boxy, honky nasal sound.

    You're right. How about if the E and G strings are first brought up to pitch simultaneously and then the A and D tuned up simultaneously to keep everything straight. Will the E and G notes drop in pitch, go up, or stay the same? This might give a clue whether the top plate was deforming outward (sound post getting looser) or inward (sound post getting tighter).
  24. Marty Kasprzyk

    Boxy, honky nasal sound.

    If you are installing strings and first tune the E string up to correct pitch and then bring the other strings up to pitch does the open E string go flat or sharp or stay the same? Do all violins behave the same way?
  25. Marty Kasprzyk

    Boxy, honky nasal sound.

    I don't think you will find any engineers disagreeing with Don's comments. But I think it's simple and basic mechanics.