Don Noon

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About Don Noon

  • Rank
    It ain't rocket science... it's more complicated
  • 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. 12-string guitars have an octave G string. It breaks a lot, but that's about the highest stress (not tension, which depends on diameter) string I'm familiar with that is commonly used. If you assume a Martin 12-string scale length of 24.9", you can calculate (or, at least I can) that the octave G would have a scale length of 376 mm if used as a viola E string. So, good music wire can take the stress (barely) of a long-ish scale viola E string... with the caveat that the drag over the nut and bridge of a viola is likely higher than on a guitar, and therefore even more likely to break. Although this is a 12-year-old post, I wonder how the breakpoint can be so clearly defined between what is a 5-string violin vs. a 5-string viola. It seems to me like a very small viola and a very large violin could be the same thing.
  2. Looks like the geared tuners are from a guitar, cut up with tin snips. In keeping with the overall quality.
  3. I think it was all a compromise to get something that held together reasonably well, sounded good, looked nice, and was not too difficult to fabricate.
  4. Here's the perfect violin structure (in concept) if you want to only think about static loads. The lower one is modified to put in a neck and end blocks so you could play it and have something for a chinrest to clamp onto. You'd need two soundposts... one under each bridge foot. I'll bet it would sound like crap.
  5. Yes, if you get rid of the flexible surround. Again, we're talking about only static support of a point load, where straight lines are most efficient by carrying all load in compression or tension in the material, eliminating bending (which is very inefficient). Arches are for distributed loads. Once you demand that the vibration behavior of the plate produce a pleasing sound and work well for the player, the whole thing becomes a compromise and impossible to resolve by any theory.
  6. I think EVERYBODY sees that bridges are arched for a reason, and so are violin plates. Arches have been known and used for thousands of years. It's not like Leonardo came up with something brilliant or new (in this case). And almost all violins are not exactly what is done for bridges anyway. Thus all the nutty tangential posts. Actually, if you wanted to make the most efficient static structure to support the bridge and string loads, it would NOT be a nice, smooth arch... as the bridge is a point load and should be treated differently. The arch I think is more for acoustic/vibration reasons, and possibly some aesthetics thrown in.
  7. The back is easier to polish since there is no bridge, strings, fingerboard, or F-holes to contend with. I think the back gets more wear in certain spots from the case and the player's shoulder, so the varnish is often gone quickly from there... but then it's easy to polish over those spots to look nice.
  8. Varnish stripper, and a different varnish. And as jezzupe says, test it first.
  9. Even the unfaded varnish looks too weak in color, assuming it's the very thick blob that it appears to be. Applied thinly, I think it wouldn't look like much. I could varnish a boat with all the stuff I have that looks fantastic in the jar, but just a light amber when applied. Oh, well... there are good pigments and lakes out there.
  10. I recall Nagyvary once touted borax as a magical treatment. I tried it for a while, forcing a solution into the wood with vacuum and pressure (it wouldn't get into the spruce otherwise). Initial tests seemed to indicate that damping was reduced slightly, although the residual borax (which is impossible to get out) added a little weight and didn't do anything good for speed of sound. Repeating the tests did NOT verify the initial result, so I have abandoned it. I do, however, put a light coating on the inside of the instrument with a casein/borate solution, with the borate there for possible insect protection rather than any acoustic reason.
  11. I would be shocked if the A0 of that size instrument was more than 10 Hz away from 250 Hz. Definitely not 207 Hz. Unless you made the body out of wood-grained neoprene.
  12. For chalk, Eternity Arts makes pretty good stuff. Lots of color choices, including fluorescent.
  13. How do you determine what is "too high"? On my small (40cm) viola that got a tone certificate at VSA2018, I intentionally made extra-large sound holes to get the A0 even higher, close to C, so that the first overtone of the open C string would get a little more power. For larger violas, that alignment is not feasible.
  14. Don Noon

    NEED ADVICE

    In my experience, a tailgut free length of more than ~5mm can allow tailpiece vibrations in the playing range that become apparent (and usually not in a good way). Afterlength effects have not been as significant.
  15. "Strength" in normal engineering terms means the load it takes to break something... which is different from "stiffness" which is more of a concern for acoustics. From what I have been able to find, bamboo is about twice as dense as spruce, and about twice the modulus, or stiffness. That follows the rough rule that modulus is proportional to density. For soundboards, density (or the inverse of it) becomes a more powerful factor, with lower density usually giving a higher figure of merit (radiation ratio). There is one glaring error in there that jumped out at me, making me a bit suspicious of the whole paper. In table 2.2, it shows the modulus of steel is only ~5% higher than bamboo. That is off by an order of magnitude. Interestingly, the modulus/density ratio of steel is approximately the same as spruce and bamboo... but since steel is so much denser, the modulus is much higher. And it makes a crappy soundboard, where bending stiffness/weight is important. (resonators in dobros are designed differently).