Jump to content
Maestronet Forums

Oded Kishony

  • Posts

  • Joined

  • Last visited

  • Days Won


Everything posted by Oded Kishony

  1. Here’s some moldy curdled milk, you try it first and if you don’t die I’ll give it a shot.
  2. The main obstacles that I see with violin ‘acoustical’ work: the difficulty in establishing causality. Because violins are so responsive and delicate (the good ones anyway) any changes in the bridge position post tension or lag in time between changes pretty much nullifies the ‘cause and effect’ impressions. IMHO the academic approach to studying violins just hasn’t proven to be appropriate as can be witnessed by the dearth of practical results or even novel acoustic techniques resulting from this work. Violin sound needs to be approached holistically, understanding that the bow/string/player generates many multiple modes simultaneously and that they change during each bow stroke. It’s what makes the violin so enthralling. I also believe that not enough attention has been given to psychoacoustic effects, both objective and subjective. Oded
  3. First thing I would check are all the seams. If the crack is still closed then it’s very unlikely it’s the cause of the wolf.
  4. I find that identifying the colors and ground of the old masters much more problematic than the actual varnish. oded
  5. Transparency in pigments is tricky. You can think of pigment colors as musical chords comprised of multiple notes, when in harmony are transparent and when discordant opaque. This is just a useful metaphor. If you smear out a pigment you can see the variety of colors. As you mix different pigments the likelihood of achieving a harmonious chord diminishes and the result is more likely to be opaque. The best way to determine the transparency of a pigment is to draw a dark black line on a card and paint your color or combination of colors over the line, it is then apparent how transparent it is. Dye colors are inherently transparent even when mixed. The painting technique you are using is called ‘glazing’ in the art world. An excellent, though possibly outdated book on color theory is “Blue end yellow don’t make green”. Oded
  6. Yes!!! I agree, you can’t change a poorly made violin into a good one, certainly not with simple external changes. oded
  7. Well, Don and I have done this dance quit a few times now. Ultimately the only way for you to know is to try it yourself. I have found it quite useful and there are a number of professional makers who utilize some version of fine tuning the instrument in the white. A few caveats: the thicker/heavier the instrument the less effect changes to the arching/graduations. When you scrape from the outside you are also making a subtle change in arching. This is very intuitive. thinking about individual frequencies/modes is not very useful because every spot on the violin affects many multiple modes/frequencies. much has been made about the question of what happens after you varnish. Certainly the varnish changes the sound but you should know (or find out) what acoustical effect your varnish has. Also keep in mind that the same is true for whatever system you use, the varnish will always change the sound somewhat. But in my experience if a fiddle sounds good in the white, it will sound good after it's varnished. randomly scraping the surface is mostly futile. You need to be able to predict what changes will occur from any given spot. I use a couple of variations based on the simple principle of reciprocity ie vibrations going from the string to the corpus (body) equal vibrations going from the corpus to the string. This means that if you scratch or tap the white (unvarnished) instrument with your finger nail you will hear different strings and harmonics start to ring out (on a tuned instrument) It is my belief (religion) that the great makers of Cremona utilized some form of this technique. It has been noted that they finished the instrument from the outside (see Roger Hargrave see below page 3) you can also use a spectrum analyzer to observe this, set the analyzer to 'continuous' with 'peak hold' and you can watch as different frequencies increase in amplitude (get louder) as you change locations. Oded Kishony 1477066518_Chap_06_Labels_PRN1.pdf
  8. The changes in the sound were unmistakable and the nature of the changes generally agreed upon. One reason these strips had an effect is because the violin is quite thin. The notes, as I recall, were brief and noted the most obvious and agreed upon changes. All the participants were very experienced violinmakers. It’s much easier to be objective if you don’t have any stake in the outcome.
  9. It’s a very ordinary Chinese violin that’s been regraduated very thin. Surface is sealed with shellac. The stffening strips are a variety of dimensions and coated on one side with rosin. To apply a strip it is placed on the surface and a heated spoon applied to the strip, melting the rosin and adhering the strip. It made for a fascinating test platform. in one experiment careful notes were made on tonal changes as strips were applied but as the strips were removed in reverse order the tonal changes did not match the original impressions. Intriguing!
  10. You know....... violin color ;-) ”Golden “ brown ok
  11. There is an historic sealer that consists of hide glue and alum. Whatever it is it was applied as a paste. I’ve seen photos of drip marks inside the ‘Il Cannone’ but they are very different, a highly colored liquid that penetrated the wood. Oded
  12. Greetings: recently saw a photo of the interior of the Messiah (Strad), it showed a thick, crustaceous, white residue, all around the F hole. one has to believe it is original.
  13. I use a baby bottle warmer with adjustable temp. They automatically shut off if they run out of water and a recycling feature that returns the bath water to the pot so it doesn’t evaporate too fast. Keep it on warm then crank it up when you need it. you can often pick these up at yard sales etc.
  14. I would not bother with the sticlac color but make the varnish with the pernambuco (and madder and other color sources like rosewood and perhaps walnut hulls) and lay down many layers of ‘water thin’ varnish. Place the dry ingredients in a silk screen bag or a womans’ Stocking foot. Use it like a teabag in the alcohol. The wax in the shellac can be helpful in improving the brush ability of the varnish but removing some of it will help clarity. I varnished half a dozen instruments this way in 1987 and the ones I’ve seen, have stood up very well. this type of varnish is pretty soft and takes a while to fully harden. It will take a while for the instrument to sound good, the soft varnish can mute the sound for a while.
  15. Good job Don, you’ve managed to slander Stradivarius’ name with your snide, fact free, sneering innuendos. Congratulations
  16. In my experience instruments with higher plate weights/stiffness are more challenging to play but often have a greater range of tonal colors. I guess it's time for my annual rant..... I pay attention to weights and tap tones and like to get within what I consider an acceptable range based on the s.g. of the wood I'm using. The quality of the sound of an instrument depends on not only the frequencies of the radiated sounds, but as importantly, the relative amplitude of the frequencies. Then there is also the effect of the stuff between the ears that is critical as well. Oliver Rogers wrote a paper (one of his last) illustrating how a viola he was playing sounded wonderful playing in one key but sounded quite bad in a different key. He demonstrated that the viola had sonic holes in the frequencies of the second example! There is no way to closely control the frequency amplitudes in the spectrum of an instrument through plate tuning. The only way that I know of exerting any control is by removing wood from the exterior of a set up, tuned unvarnished instrument. Yes varnishing does change things a bit, but a clear sealer reduces that effect and an instrument that sound good unvarnished should sound good after it's varnished (change your varnish if you don't agree) Scraping any particular spot will affect multiple modes simultaneously and while one can perhaps discern that 'something is different' this random tinkering is mostly useless. In order to affect the timbre of the instrument the changes need to be focused. I believe that the great violinamakers of the past may have accomplished this by setting up their violin, tuning it and finish scraping while listening to the open strings vibrate to the fundamental and harmonics. Modern violinmakers can use a spectrum analyzer in a similar way. As the instrument is scraped one can see sets of frequencies responding and changing as the location of the scraper changes. If the area is further thinned an increase of amplitude can be observed. Here is what I believe is an example from a great violin. (Messiah by Strad) I was struck when I saw these ripples because this is such a typically acoustically sensitive area of the violin. This is exactly what it looks like if you're trying to affect the tone of the instrument from the exterior! Oded Kishony
  17. “it’s only a violin” I.e. not a sacred relic..... oded
  18. Yes, this wedge is used to level a 'step' in the plate. It's easier to visualize if you think of getting the two sides to first line up, using your fingers, then inserting the wedge, effectively making one leg a little longer than the other. It works, even if it doesn't seem obvious. The over sized hole is on the lower thumb screw, on the knurled side, to allow the towers to 'rack' a bit, otherwise they would always be perfectly parallel and you couldn't correct the arch. Oded
  19. a couple of points: after very carefully lining up the crack (dry, no glue) I glue the cleats in place. This holds the repair in place when I later apply hot glue on the varnished side. I sometimes loosen the upper screw a bit and ‘pump’ the glue into the crack and then reset the screw, always checking for alignment. I use 3x5 card stock for the paper at the base of the pillar. To speed things along I put a dab of very thin hide glue on the plate and use ca glue on the pillar to get an instant bond without introducing ca glue to top wood. I like using the magnets, despite the fact that they can be a bit tricky, because they are light weight and this clamping method does not impose any torque on the plate and allows you to more easily handle the plate. Oded Kishony
  20. I got my magnets from K&J Magnetics. https://www.kjmagnetics.com/proddetail.asp?prod=D84PC-BLK The thumb screws, both brass and nylon can be purchased from an industrial supply like MSC or Grainger https://www.grainger.com/product/GRAINGER-APPROVED-Thumb-Screw-4NHT8 or on Amazon https://www.amazon.com/Knurled-Head-Thumb-Screws-Machine/dp/B01729GGR2 or nylon ones at Home Depot https://www.homedepot.com/p/Everbilt-8-32-x-1-in-Nylon-Knurled-Head-Thumb-Screws-2-Pieces-26388/202209622 Oded Kishony
  21. Would your measurements reveal improved responsiveness? Did you check for that feature? OK
  22. I've tried various versions including an off center motorized twirling device clamped to a cello bridge. It made a huge roaring racket. Didn't seem to help the instrument very much (didn't hurt it either) I met a vioinmaker, years ago, who connected a violin to a radio via speaker driver with a stick glued to it, touching the side of the bridge. He claimed that when he first set it up he had to crank the volume all the way up to get any sound but over time he was able to reduce the volume setting significantly and the instrument worked very well as the 'cone for the speaker. Or you could try Micheal's gizmo. I don't think it matters too much what you play through the corpus (Limbaugh will ruin it though ;-) but this is something you could do that will not offend your wife since it will just be another audio device playing. Oded
  23. This photo illustrates how you can use this clamp to align a crack that has a 'step'. Notice on the right side of the crack is a narrow wedge that pushes against the screw shaft effectively pushing down that side of the crack. To glue the pillars in place I put a dab of thin hide glue with my fingertip on the surface, let it dry a bit and use ca glue on the pillars that are surfaced with paper (I use 3x5 card paper). Oded
  24. I use this flanged nylon knurled screw and a brass version with the corresponding tap. The lower screw is used to pull the clamp together, so the hole on the left is slightly oversized to allow for some degree of movement and the opposite side is drilled through and tapped. The upper part, drilled and tapped on one side, is used to spread the clamp.
  25. I've developed a clamp and procedure for this that works very well. The shop made clamps using hardware that costs apx $0.25/clamp plus scrap maple two drill bits and one tap. I use plastic covered rare earth magnets instead of clamps because they are light weight and clamping pressure is only vertical (no torquing from clamps). The plastic prevents scratching and glue does not adhere to it. Magnet clamps can be a little tricky to control. I 'park' the magnets alongside the cleat then slide them in place, lifting the one that goes over the cleat. If you get the magnets too close they tend to 'jump' out of control. I dry clamp everything, checking the alignment with a straight edge across the crack, glue the cleats in place then after the glue has dried apply glue to the warmed varnished side. Glad to answer any questions. Oded Kishony
  • Create New...