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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 wh
  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. b
  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 curtat
  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 m
  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 requir
  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
  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.
  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
  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 var
  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 wh
  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
  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 g