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Everything posted by donbarzino

  1. Where are you holding and tapping the plate ? You are probably exciting some higher modes that happen to share nodal points with your core or ring mode and those higher modes sound like they are harmonically related to the frequency of your main mode. This could be good or bad. I would note it and see how the violin turns out.
  2. Do you have any idea of what the thickness of the top plate is around the sound post area ? A too great thickness or stiff sound post patch would possibly cause this effect.
  3. I believe we are incorrect in conceptualizing thickness graduating and arching as separate processes. Any removal of material, as in graduating, also changes the arching. Removal of material from the outside increases the radius of curvature of the arching thereby softening the arch and removal of material from the inside decreases the radius of curvature thereby stiffening the arch. I do assume that there is some more ideal state to be achieved by careful adjustment of everything, especially graduations and arching. These processes are some of the most sensitive, interesting and exciting aspects of making a violin. Without centuries of patient application of them by instrument makers our poor musicians would still be beating on rotted hollow logs.
  4. I cannot see any brand inside but will look more carefully when I find my light and mirror. Moving is hell. Ben Franklin said 'three moves equal a fire' and indeed I seem to have misplaced or damaged nearly a third of my possessions in this move. Yes, it is large at 360 mm.
  5. This violin has lain around my shop for many years forgotten until my moving recently unearthed it. The label reads Francisco Lupot in Orleano 1764 I acquired it from a pawn shop for which I was doing repairs in this condition . It clearly needs restoration and your expert opinions will help me decide whether it is worth doing. Thank you for your attention to this matter.
  6. For what its worth, the Kay plywood double basses of the 1930s-70s featured what appear to be maple sound posts and they are considered to be among the best playing and sounding of plywood basses.
  7. I have been buying and using wood for double bass and cello for many years and have amassed a large collection of one piece tops and backs. While the grain lines aren't close enough to satisfy some of you those who believe bigger is better might find this little scrap to be titillating. That is a two foot steel ruler on top.
  8. I have used Port Orford cedar for several bass tops with good results. Michael Darnton only mentions Port Orford cedar as cypress which it is, actually Lawson's cypress. It works well, is quite crack resistant and fills the shop with its strong odor as it is worked. The tone was more dominated by the fundamental and lower harmonics and quite acceptable for orchestral basses. I had also good luck with tulip poplar for bass ribs and backs. It is intermediate in weight between willow and maple, works very easily and also favors the lower harmonics over the higher.
  9. Jack Fry thought that varnishes ideally lost much of their damping by forming a network of microcrystalline cracks. The cracks allowed the varnish film to flex as a series of free hinge joints instead of the bending action of a continuous film. He demonstrated his theory by opening up the tone of a heavily varnished instrument through heavily x-raying it to induce the micro cracks. He also believed that varnishes were supercooled liquids held below their melting point and like window glass they slowly ooze and heal the cracks if not flexed regularly. Hence instruments going to sleep after not being played for a long time.
  10. I believe the stiffness is proportional to the thickness squared so a 25% thicker rib you suggest would be 62% stiffer. Many years ago a violin teacher of mine paid Carl Becker to thin the ribs of his lovely 18th century Italian violin and raved about how the tone improved and opened up from the operation. I like starting out with ribs on the thick side and scraping them thinner from the outside. From making double basses I can tell you that the ribs definitely resonate on their own and also interact with the plates and that you can tune them to work together.
  11. I have found that scraping along with the grain with the scraper oriented parallel to the flames accentuates the flames. Conversely, to minimize the flame texture one would scrape in a crossgrain direction with the scraper oriented perpendicular to the length of the flames.
  12. Flames certainly are considered a weakness because of the runout . Flamed boards are not allowed for use as stair treads by code. I think flamed wood is used for violin backs specifically because of the weakening effect which also slows down the speed of sound along the grain.
  13. I greatly enjoyed reading "A Thousand Mornings of Music: The Journal of an Obsession with the Violin" by Arnold Gingrich.
  14. I like your doodles very much and can visualize how they will add a nice personal touch to your instrument. Applying a light coat of clear varnish on the areas you wish to paint upon would make it easier to remove your doodles in the future. Remember, you are not the final owner of that viola.
  15. I looked into spaulting at Forest Products Laboratory Library years ago. As I recall the black lines form at the interface between competing species of fungi. In maple they found a 1% strength reduction and a 1% weight reduction. I understand the modern Cremonese makers have resorted to using spaulted wood years ago.
  16. Yes, but he would have flipped one side relative to the other so the runout matched.
  17. Stavanger, I would reject that piece of wood because of the longitudinal grain runout revealed by the strong harlequin effect, where one half of the back reflects light differently than the other. The beauty of the flaming is marred by the two tone effect.
  18. I question the necessity of using hardened steel. Its not really doing any terribly strenuous work. I have sometimes found it advantageous to be able to bend my setter to fit different situations and have been able to do so with my self made brass one. As to weight I would say the more the better especially in the head.