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About elderthomas

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  • Birthday 08/25/1930

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  1. Torbjörn : I am not aware of any mechanical method to generate the modified cycloid curves. Regarding the other speculation about whether the deviation from the perfect curtate form can be explained by age and stress related distortion, from fitting about 5 different Strad posters and observing the deviations, I don't believe they can be explained entirely by age and stress. From an intuitive standpoint I find it hard to believe that the old masters settled on the perfect arch as being an exact curtate cycloid. I suspect that their approach was primarily based on a cut and try method where they experimentaly determined which arching gave them the results they considered best. I would imagine that other than tone and responsiveness, esthetic form considerations were important. This is why I am suprised at how close their archings are to even a modified cyloid form. For what its worth Regards
  2. Dave, Where did you download it from? Its been quite a while since I put the arching program on the website, and I've forgotten what files were with it. If you would like the Milanolla files for the arching program I can post them separately. Let Me know by PM. Bye the way I should clarify why I put the drawings on the forum. I have seen a lot of discussion about curtate cycloids and how they approximate the archings on the Cremonese instruments. So I thought it would be interesting to see just how well they fit. As you can see some of the arches do match the curtate cycloid quite well. but from the Milanolla and others that I have fitted, more of the arches deviate from the exact curtate cyloid form than fit it. Unless, of course, you are willing to include the shape factor modification in the Curtate cycloid family. I don't want to nit pick the subject. However, the thing that suprises me is how good a fit you can get to almost all of the arches if you modify the cycloid equations with a shape factor. Regards, Richard
  3. Torbjorn Sorry I don,t know how to make the umlaut. The green curves are modified Curtate cycloids. Mathmatically they are curtate cycloid equations that have a multiplying factor which I call the shape factor. If the factor is 1 the curve is an exact curtate cycloid. <1 gives more concavity near the edges, >1 give more convexity near the edges. You can get the program to generate these curves on my site http://mysite.verizon.net/vze3zndd/.
  4. Sorry I didn't get both files attached to the first reply.
  5. Since the subject is curtate cycloids and their relation to Cremonese instruments. I thought some of you might be interested in seeing some drawing showing how well the curtate cycloid fits the front and back on the Milanolla Strad. The arch lines in black are from the Strad poster. The Red arches are exact curtate cycloids, and the Green lines are best fits from my Arch Fitting program. As you can see the exact curtate cycloids do fit in some cases but others require quite a large Shape factor (SF on the drawings) modification to fit the poster arches. A SF of 1 corresponds to an exact curtate cycloid. Just thought there might be some interest in seeing these. Regards
  6. Introducing a slight variation on the "playing in" concept. I am sure most of you have heard comments by professional violinists that "When a violin is played for a significant time by a poor player. That violin will sound bad if next played by a good player. At least initially until it is "played in" for a while by the good player. I would be interested to know how many players and makers subscribe to this concept. My meager experience tells me that if I (a poor player) simply saw out double stops for a while on a new violin the violin will usually start to sound better to me. This I can rationalize to some extent, but I can't imagine what the mechanism would be that would allow the violin to remember the quality of the playing it has experienced. Any thoughts?
  7. Mauricio You may be right, varnishing may even things out some. Thanks for the string suggestions. Henry, I am aware that some violins sound loud under the ear but don't project as well as some that are not as loud under the ear. In this case my wife tells me that it is loud across the room. But I have a "Cannone" model that sounds relatively quiet under the ear, but loud across the room. She thinks that the Viotti is comparable in projection to the "Cannone". I have others that don't project as well, according to her. One thing I notice about the Viotti is that it requires very little bow pressure for lots of sound. Regards Richard
  8. Manfio I am using Dominant strings, and the afterlength is 56 mm. What did you think you might have said wrong? Melving You and Michael are probably right. but for reasons I explained earlier, I decided to try it like it was. For about 10 violins I have used the tap tones as something of a guide. I have usually found that the thickness was about right with the the mode 5 tap tone was about 360 Hz. The exception being a Milanolla model and the "Cannone". I graduated them both according to the poster thickness, ignoring tap tone. The Milanolla gave a deep hollow tone (not good). The Cannone of course sounds fine after being played enough. For this violin at 3.5 mm the top seemed quite flexible. I didn't want to get another boomer, and since I can always take it off, but can't put it back on. I went with it as it was. That will give you an idea of the things that influenced my decision. The E and G are not bad but they don't seem to come out like the D and A. Could this be setup, or due to excess thickness? Cassi I think that the biggest problem in interpreting the measured thickness of the old master's violins, is that (from what I have heard) most of them have been regraduated. I believe this was done to get greater projection out of them. I could be wrong about that last. Others in the forum can address this better than I can.
  9. Glad3600 Yes I know that a day isn't long enough to really play it in. However, I did notice an improvement after a day. (Lots of double stops). Manfio, To my untrained ear the sound isn't bad at all and the D and A strings sound very good. Lots of complexity, in the tonal quality, as well as good projection. Because there is some unevenness in the string response (subdued G and E) It has me at the point where I am uncertain whether to leave it as is and varnish it or to take the top off and remove at least another 0.5 mm. I do believe it will improve more. with playing. I spend a couple of hours moving the sound post around this afternoon, and each new position sounded worse than the original placement. Trouble is I don't have a lot of time to invest in playing it everyday. Decisions-decisions. Cassi, What Manfio said. Thanks Guys
  10. Hi Manfio, I understand what you are saying. But I was wondering if you have any specific tonal characteristics you would expect if the top was too thick. Or are the possibilities too extensive to list. I remember the "Cannone" model that I made was muted at first, until it was played for a good while. I guess I would have expected to get a similar response from this Viotti model if the plates were too thick. Regards,
  11. Hi everyone, I want to thank you all for your previous thoughts and suggestions I'm rejuvenating this old thread because I have strung the violin up in the white. As I mentioned I left the plates thick, 3.5 mm on front and 3 and 4 mm on the back. I did this mainly because the top plate felt fairly flexible at this thickness, and the tap tones where where I normally find them. I thought I would see how it worked out. I have been playing it for a day or so now and it seems to have plenty of projection. If I could single out any problem are it would be that the G and the E are some what subdued relative to the D and A (not really bad). The D and A sound good to me. I believe the sound post is well fitted, but I have not made any attempt to optimize its position. My question now is what symptoms would I expect to find if the plates (especially to top) is too thick for optimum tonal quality. I am still considering the possibility of thinning the top plate. Any comments?
  12. Lance, I think the issue here is that the plates are 'too" thick everywhere. Especially the top plate, which is graduated pretty uniformly to 3.5 mm. I guess I could remove some wood in the center, but that would still leave the upper and lower bouts pretty thick. If I remove wood from the center of the back it would tend to make the back more uniformly graduated instead of the conventional 'thicker in the center' pattern. Am I missing your point? My plan now is to leave it as is, and if it doesn't sound right remove the top and thin both the top and bottom down before varnishing. I was especially interested in finding out if anyone else had found significant differences in the thickness - tap tone relation for different woods. In this case the top is especially low density compared to other wood I have used. Regards Richard
  13. Michael, I appreciate your input. I am familiar with your views of plate tuning. I am no expert either. I do know that you can achieve a wide range of mode frequencies and still control the average thickness. But that usually requires that you graduate unevenly, and its a fairly complex process. trying to raise or lower a particular mode by removing material on the nodal lines or in the anti nodal regions. I try to graduate uniformly (at least on the top) and use the frequency to tell me something about the stiffness of the plate. For most of the wood I have used I find that when mode 5 is around 350 Hz I am somewhere near normal thicknesses. But this wood was different. I don't like to blindly graduate to a given thickness and hope for the best. Until I develop a better 'feel' for what I am doing, I will have to use something like the mode frequency as an indicator. The fact that this wood behaved differently from most of the other wood I have used, was sort of a red flag for me, and I didn't want to proceed further without getting some input on it. I think I am going to go ahead with the present thicknesses and see what I get. If I don't like it, I will take the top off and re graduate it before varnishing. At least I will have learned something by first hand experience. I will let you know how it turns out. Bye the way Michael. a couple of years ago I made a 'Cannone" model, and used the thicknesses given in the poster. When it was first completed, It sounded muted and I was thinking about re graduating it. You advised me to leave it be and play it. I took your advice and now it is probably the best sounding violin that I have made. It is quite bright but projects well. Thanks again. Glad3600 The wood I am using is from SVS tonewood. for most of what I have obtained from them in the past , the spruce has a density near 0.4 gm/cm3 and the maple a little over 0.5 gm/cm3.
  14. Thanks Manfio and Oded. I am going to go with your suggestions and leave it be. Bye the way Oded the top plate is a little heavy at 78 grams. But as you say, if I am not happy with the sound, I can always open it and regraduate it. GJW thanks for your comments. I am glad to hear that someone else is trying the Viotti. You didn't mention if you measured the tap tones (in particular mode 5). If you did I would like to know what the frequencies were. Your weights are in the normal range for wood that I have previously used. As you can see my weights are higher. If I had taken mine down to your thicknesses I would probably have had weights similar to yours. As I mentioned in the original message, I am wondering if the arching has anything to do with the lower tap tones. I hope that it turns out well for you. Let me know what it is like.
  15. I am making my 13th violin based on the Viotti Strad. I usually use the mode 5 tap tone as a measure of when I am close to the right thickness. On previous plates when the tone is about 360 Hz the thickness is close to what one expects it to be .i.e., 2.5 to 3.5 (mm) on the back and about 2.5 on the front. However the Viotti plates seem to run quite a bit thicker. When the tap tone is 350 on the back its thickness is 3 to 4 mm. At 330 Hz on the front the thickness is 3.5 mm. The wood density on the back is 0.56 gm/cm3 ,a little on the heavy side, (back plate weight is 135 gm) and the front is 0.36 gm/cm3, lighter than usual (front plate weight is 78 gm). The Viotti poster gives about 2.3 mm for the front and 2.3 to 3.3 for the back. I realize that some of the best makers don't put much stock in mode tuning, but it is about the only thing I have to go by other than thickness. My best estimate from flexing the front plate is that it's stiffness is about right. Since I don't have much experience to go by I am uncomfortable basing too much on my estimate of stiffness. Hence, I am at a loss whether to take them down to more conventional thicknesses or leave them be. I was wondering if the arching on the Viotti would account for the difference in thickness. The Viotti seems to have a little more scoop than the Milanolla and Betts models which I have used previously. I would appreciate any thoughts and suggestions. Richard