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Don Noon

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About Don Noon

  • Birthday 03/20/1952

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  • Gender
    Male
  • Location
    Carlsbad, CA
  • Interests
    Acoustics
    Violin construction
    Varnish
    Old-time fiddling

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  1. Gamsol is great if you want it to go away clean and fast. How well it mixes with things is important, and I think it's not the mixiest of the solvents out there. I would also prefer slower evaporation. Joe - I know nothing about the cemistry.
  2. Mike Molnar sent me some Rosemary oil and Lavender oil (both from Woodfinishing Enterprises), and I did a few evaporation tests along with some other solvents. I started by putting a drop of each solvent on a ceramic plate. Results so far: Gamsol - lowest viscosity, spread out quickly and quite far. Evaporated completely in 1 hour, no residue. Rosemary oil (WFE) - spread nearly as well as Gamsol, but dried more slowly. Even after 1 day, there was a thin, oily/greasy film. After 2 days it seemed to be all dry. D-limonene - spread pretty well, dried to a hard film in 1 hour where it had spread thinly, but not in some of the beads at the edges. After 4 hours, it was all dry. Lamp oil - spread slowly. Didn't seem to evaporate much in the first few hours. After 1 day, a thin, oily/greasy film was left. After 2 days, it was dry. Lavender oil (WFE) - more viscous than the previous ones, spread slightly. Still very wet after 1 hour, but in 4 hours dried leaving a hard film. Lavender oil (internet inexpensive) - by far the most viscous, minimal spreading. No apparent change after 2 days. (I had previously tested this, and it didn't dry after a month). So, yes... source matters a lot especially for organic solvents like this. And this is only evaporation and residue testing, not considering how well it solves in varnish or wets onto previously dried varnish coatings.
  3. While the high frequencies do seem to be more mysterious and unfathomable, my experience with regraduating very thick tops (I mean REALLY thick student type violins) is that the high frequencies (2-4 kHz) can be attenuated by overly thick tops. The bigger change is in the lower frequencies, though. Once the thickness gets into something reasonable, then the high frequencies become more mysterious and unfathomable.
  4. Probably. It's difficult to say what the "something" is, and whether it's desirable or not. Lower modes have larger antinode patches, so it's easier to see what's happening even with the hidden zone under the fingerboard. Each mode has its own shape... but from looking thru the Strad3D modes, it appears to me that the upper bout has more HF activity, which matches my experiments and hearing. Looking at the air wavelength, even at the high frequencies, I think the fingerboard is too narrow to do much in the way of reflection or setting up any kind of resonance. The sound will just squish around the fingerboard.
  5. 1) I am confident that you assume incorrectly, and that is what is interesting... exactly where and how the plate actually vibrates. 2) ? Yes, each resonance is its own thing... but I have no clue what you mean by that first part.
  6. I think there may be... we just don't understand it yet. I think it is pretty clear from close listening to a voice-coil driven body that there is a lot of high frequency sound coming from the upper bout. This is an internal air resonance idea, which might not be obvious to others. I drilled a number of small holes in the back plate of a violin, just big enough for a small microphone, to check for this. I could not find any evidence of such a resonance, even though it seemed like a good idea. Ribs too, to check for lateral resonances. Nada. A0, for sure matters. A1 can be measured, but doesn't seem to do a lot. Above that, I don't see much evidence.
  7. Basically, everything blanked out by the fingerboard, which is more than your diagram. This is a mode at ~3000 Hz, and shows there's something significant going on under the fingerboard. I'd like to see the details. Marty, I don't see how you can attribute a preference to A0 alone, as it is a function of construction features which may (and I would say probably are) creating other tonal effects which are preferred. Most notably, I see that lighter tops appear to be even more strongly correlated to preference, and presumably lower A0 is inversely correlated with plate weights... thus lighter plates might be the driver for preference, and lower A0 just a meaningless side effect. I think it is notable that the highest preference went to the viola with the 2nd lightest plate, but was also among the highest A0 frequencies.
  8. Of course you can. You have Audacity... play a note and look at the FFT spectrum of it. Where the overtones are the strongest will vary radically from note to note, as the body response has all kinds of sharp peaks and dips in the high frequency response. Really good violins I think will have less dips, and thus more overall output in the overtones. I'm not that quick to dismiss arching. While the patchwork of antinodes might appear to ignore arching, according to my estimates, the arching can do significant things to area of the antinodes, which in turn would do significant things to output. It is a shame that the Strad3D animations are blocked by the fingerboard, and can't show what's going on in this critical area. Here the crossarching is usually the tightest radius, and where I believe a major part of the high frequency power radiates from. Ignore facts at your peril.
  9. If you have a Godzilla model, that would ber a good start. My very first carving was a snakehead, for which I purchased a real head of a rattlesnake on eBay. It was handy to see how the scales were shaped and how they fit together around the mouth, nose, and eyes. I didn't want the spade-shaped rattlesnake head, so I modified it to look nicer. If you want to do scales and small surface features, you will likely need very small, tight-radius gouges. I made 2 small ones from scrap HSS for the scales.
  10. Presumably thise dB levels are the composite loudness as measured by a microphone. To evaluate the loudness as perceived by the human ear, I think you'd have to take each harmonic component, adjust it by the ISO loudness curve, then recombine it all. Then it doesn't really tell you whether the sound is generally desirable or not, which is something else entirely. Marty - re: 5 string viola with A0 at 196Hz... yes, you'd get some more roundness on the low G string notes. However, that does other things. On the low C string, the A0 is still too far away to help. And looking at the next 3 overtones, the fall into response dips, which seems to me would make the low C string extremely weak. I have taken the opposite approach on my viola, using relatively large F holes and small body to keep the A0 up around C, where it gives some reinforcement to the 1st overtone of the C string. The size of the plates shifts the other resonant frequencies down relative to the violin, giving a tone that is distinctly different from the violin without getting to radical about things.
  11. One would think that the recent shut-down of the Apple Daily sends a message that if you run a private media company and want to keep operating, publishing good things about China will help, and you'd better not do the opposite. So although the content may come from elsewhere, deciding which content gets repeated is likely getting a slight nudge from the political environment, although not directly from the government
  12. BTW, I checked the edges of the samples posted earlier with an eye loupe to see how deep the flames were. On the leftmost sample, I estimate about 10 degrees variation from longitudinal. Middle samples 20 - 30 degrees. Deep bigleaf: 45 degrees commonly, with occasionally more... some folded 90 degrees. Wanna guess how much fun it would be to try to bend that one? Such deep flame I think loses the 3D effect and looks burned, as it takes such a huge viewing angle change for the flames to move.
  13. There is definitely an abnormal sound to these instruments. You could say that they sound like their maker.
  14. Neither. Specifically, W/N Blending-Glazing medium, which is perfectly clear. WIth just resin/solvent, it was too thin, penetrated thru ribstock too easily, and dried way too fast. The medium was added to slow things down, and cooking (not very hot) was done to evaporate the most volatile stuff and thicken it up so it didn't wick into the wood so far and fast. Appearance-wise, the thickened version ends up looking no different from the thin version; it's just easier to work with and avoid soak-thru. Mostly, I posted the photos to point out that the starting color and flame of the wood makes a huge difference. Gotta test every time.
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