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Marty Kasprzyk

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Everything posted by Marty Kasprzyk

  1. Put it into smaller and smaller bottles to limit the air space. Excessive air exposure often badly affects wine and some people do purge partially empty bottles of wine with inert gases. Although these gas purging devices and their small gas cylinders are relatively inexpensive I have found it is better to simply drink all of the wine in the bottle.
  2. The violin body is not an amplifier--it is an energy transducer. It converts the vibrating energy of the string into the vibrating energy of the violin's body, which converts this energy into the vibration of air which is sound. Nothing is amplified--no additional energy is added. A vibrating string produces nearly no sound because the narrow width of the string is too narrow to move much air. The violin body merely adds more surface area to efficiently move air. All the original harmonics of the vibrating strings are converted into harmonics of the sound produced. No new harmonics are produced. Some of the string's harmonic energy conversions are more efficient than others due to the violin body's various resonance peaks and valleys. This makes the sound output of a note's harmonics louder or softer. A note from a bowed note does have some non harmonic noise from various sticking and sliding of the bow hair on the string. If you play a single note and do an Audacity plot you will see some random noise between the harmonic series. For example if you play an A note with a frequency of 220hz, its next harmonic will be 440hz, and the next one 660 etc. In between these peaks there will be many much lower random noise peaks between the 220 and 440 peaks etc. But this noise is not created by the violin body--it is produced by the string/bow interaction. The violin body merely converts this random string vibration energy into sound noise energy.
  3. The wings vibrate widely at their resonance frequency but they are too small to produce sound. However due to a conservation of momentum if the wing is going up and down some thing else is going down and up at the same time. If this other place is big enough such as a node of the top plate at this frequency it will produce some sound. Placing a weight on the wing tip will lower its resonance frequency and some plate region will vibrate at this frequency and produce more sound at this lower frequency and the change can be heard.
  4. If the tuning fork pitch is the same as the frequency of one of the violin's resonance peaks the sound will be loud. If it is the same frequency as one of the valleys between the peaks the sound will be much much less loud. A bowed string has many harmonics which are integer multiples of the fundamental pitch f: 1f, 2f, 3f, 4f, 5f, 6f..... the amplitudes of each of these harmonics follows a decreasing sequence 1/1, 1/2, 1/3, 1/4, 1/5, 1/6.... This forms a "saw tooth wave" form. Each one of those harmonics can fall on a violin's bridge resonance peak, valley, or some where in between. So some of the harmonics might be high amplitude while others low and the resultant note will be a summation of all of these different amplitude harmonics. Thus the bridge's frequency response curve acts as a filter which changes the shape of the bowed string saw tooth wave. The violin's body acts as another subsequent filter with its frequency response curve changing the amplitudes of all of the note's harmonics which further changes the shape of the bowed string's saw tooth curve. This is shown in the attached diagram taken from one of Colin Gough's presentations https://acousticstoday.org/wp-content/uploads/2016/06/Gough.pdf Thus a filtered bowed note for example can sound "boomy" and loud if its fundamental frequency and its second harmonic happen to have a high amplitudes and conversely the note can sound "tinny" and weak if the first few harmonics have low amplitudes. Every note has a different series of harmonics and it is apparent that the sound character and loudness of each of these notes depend upon how their harmonics are filtered by the bridge and violin body. If you are a serious student of the support I suggest doing a Google search on "Colin Gough, violin" and read many of his free publications and watch his Youtube presentations.
  5. If you are making violas I suggest having a commercial table at the American Viola Society Festival if we ever get over this Covid mess. Many players and educators go to these. There are other similar viola organizations and events.
  6. Stradivari had about 90 unsold violins in his shop when he died. With many more years of hard work I think I can do that too.
  7. Rocks are heavy. Putting powdered rocks on a violin makes it heavier and less loud.
  8. The shape of a viola can be approximated by a circular disk which has a fundamental mode frequency f proportional to its thickness t divided the radius R squared: f ~t/R^2 This can be rearranged to show the the thickness t is proportional to the frequency f times radius R squared: t~f R^2 So if you want to keep the same mode frequency to keep the same sound character of the Quarneri viola the thickness of your 85% smaller viola should be reduced by about 0.85^2 or 0.72 or 72%. This assumes the wood has the same speed of sound which never happens.
  9. That's what I think too natural looks best. If you like dark colored wood, use a dark colored wood rather than using a light color one with stain or colored varnish. There's plenty of choices--cherry, walnut, chestnut etc. What kind of pie did that turn out to be? Along the same lines, I like straight apple pie with no added spices at all--no cinnamon, nutmeg etc. No sugar either. What
  10. I suggest the quality (sound, appearance?) has to be better than Chinese instruments at the same price.
  11. I would cut the eraser's excess height off and color it with a black magic marker.
  12. That's a good question. The traditional violin's lower notes on the G string aren’t very loud as shown in the old 1937 Saunders's tests of Strad violins (attached graph). If you like this (flaw, deficiency, idiosyncrasy?) then you should try to place the A0 frequency in the usual spot around 280Hz. Schelleng had shown in 1962 in his attached graph that the G string’s low frequency out-put was due to the low end tail (light line) of the A0 resonance was out of phase with the low end tail of the B1- resonance (dashed line) so the two vibrations cancelled each other as shown in the (heavy line). So if the A0 resonance frequency is rather high and close to the B1-frequency the lower notes will have a very low fundamental frequency amplitude and they will be weak and also not very deep sounding like a typical Strad violin. About a half century later in 2013 John Coffey (previously attached report)also noticed this phase cancellation effect between the tails of A0 and B1- resonances and he recommended: "Theory predicts a 180 ○phase change of sound radiated from the f-holes relative to that radiated from the top plate, as the frequency increases from below to above A0. Below A0 these sources interfere destructively, reducing the sound volume. This suggests that A0 should optimally be only a little above 196 Hz (open G) on a violin – say at A (220 Hz)." So I recently strung up one of my experimental violas with an E string to give EADG tuning like a violin. It has a low A0 frequency around 220 Hz like Coffey had suggested. Sure enough its frequency response curve did have a much higher responses from 196 to about 250Hz compared to one of my violins (see attached graph) and the Saunders loudness curves did show the viola have much better G string loudness (another attached graph) as predicted. So finally getting back to the original question of how close the A0 frequency should be to B1-? Forget all this stuff and just make them the same old traditional way so you can sell them.
  13. I agree. It takes a huge increase in the f hole area A to raise the A0 frequency. I think it follows the A^0.27 relationship that Bissinger found. John Coffey's 2013 paper (attached) beats this A0 subject to death. After 65 pages describing his carefully done experiments and analytical studies he concluded: "I suspect from these studies that the main function of the f -holes on the sound from a violin is simply to let the sound out – to allow the back plate to contribute to sound radiation and so give adequate loudness." But the wall compliance seems to have a big effect. Bissinger's translation (J. Violin Soc. Am.:VSA Papers 2019 Vol. XXXVIII, No.1)) of the paper by Hermann Meinel "On Frequency Curves of Violins" has a graph (attached) which shows how the A0 amplitude increases greatly as the plates are thinned. 609760676_JMC-HelmholtzResonance--Up-ct.pdf
  14. I agree --bigger f holes are better. Claudia Fritz (attached paper) found that it takes about a 20% change in A0 frequency to be even detectable. But If you change the amplitude of A0 it takes only about 10% change to be detectable. George Bissinger (attached paper figure 4) found the a big difference between "bad" and "good" violins was that good violins had a higher amplitude A0. One way of increasing the A0 amplitude is to increase the f hole open area. Thus increasing the size of the f hole opening might be a better way of increasing the A0 frequency (not very important) than decreasing the rib height. Fritz--perception of changes.pdf Bissinger, directivity.pdf
  15. Hi Anders, When Carleen Hutchins and John Schelleng designed and built the original set of their Octet instruments the A0 frequencies for their large bass, small bass, baritone, and tenor were all much lower than they wanted so they cut down their rib heights a lot to increase their A0 frequencies. I've plotted the % increase in A0 frequency vs. the % of rib height reduction which is shown in the attached graph. I've projected those four data points down to zero which is shown by the straight line which has a slope of 0.33 so one percent of rib height gives only 1/3 percent increase in A0 frequency. George Bissinger has later done considerable experiments on the AO frequency when the volume of an aluminum violin is changed by filling it with water to various amounts. He found the A0 frequency is inversely proportional to the volume to the 0.27 power. That is also plotted in the same graph as grey dots which is very similar Hutchins data projection.
  16. I don't like the sound of a violin's G string lower notes at all when the violins have a typical A0 frequency around 280Hz. I like the sounds of the lower notes on my viola's G strings better when the viola's A0 frequency is below 196Hz. So now I think a large viola with EADG strings sounds better to me than a standard violin. Ive been using Helicore long scale light tension viola E steel strings. From this I've concluded that the violin was originally designed for gut strings and short players with short arms and small fingers.
  17. The article's conclusion says: " The final, and probably the most important conclusion of this study, is the fact that variations in the material parameters23 can only be compensated by changes in the outline of the violin," That's not very helpful because the only outline changes that can be done are the ones to make the violin's outline smaller. The resultant violin still has to fit into a standard size case.
  18. The shaft of the Wittner pegs is knurled with fine ridges so the strings don't slip. Only a wrap or two of the string are necessary. I cut off a few inches of the string's end to greatly reduce the amount of peg turning which makes it much faster to do. A drop of super glue on the cut string end prevents the silk from unwrapping. I found it is best to put the glue on and let it thoroughly dry before installing the strings.
  19. Was anybody able to listen to the whole thing? I used to like Max Bruch. I felt sorry for the musicians playing the same thing over and over.
  20. I agree that an outside bass bar on the back should be very helpful. Make it real high and then shave it down to get where you like the sound. Decreasing the rib height requires a big reduction. Attached is a graph showing how the A0 frequency might change with rib height if you use George Bissinger's frequency dependency of the violin cavity's 1/volume to the 0.27 power relationship.
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