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Don Noon

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About Don Noon

  • Birthday 03/20/1952

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    noonviolins@gmail.com

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

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  1. A screw negates any weight savings from the tapered block.
  2. I don't think there can be any certainty about these kinds of details. The example slab-cut isn't absolutely perfectly on the slab all across the board; there's a skew angle toward the edges. If you cut the arch to follow the annular rings, that would get the whole plate closer to the slab direction. The other way, the skew would be stronger in the steeper part of the arch, and thus be somewhat less stiff... recalling that a skew angle of ~45 degrees is about the lowest crossgranin stiffness you can get. All this theory gets nowhere, really. The variation in stiffness due to skew cut isn't likely to be much (as opposed to spruce, where the rectangular cells make the off-cut angle quite important). Good luck trying to guess if these small differences make a sound difference, and I have no clue if skew vs. slab is more or less prone to cracking. I suppose that having the arching follow the annular rings might give a slightly more uniform look, but again who knows.
  3. I suppose if I had a great-looking slab back like that one, I might be tempted to use it. But there are great-looking quartered backs too, and for the previouly mentioned reasons, that's all I'll purchase... unless some client gives me a pile of money upfront to do otherwise .
  4. I'd like to see some statistics on the % of slab backs that crack, vs. quartered backs. I know it's only anecdotal, but I recall looking at some old-ish violins in a shop, and thought it was alarming how many of the slab backs had cracks. Even without seeing that, I can think of no good reason to use a cut that's more questionable physically,.. other than perhaps make a copy of some famous slab-back instrument. Or if a client has some strange attraction to the look of a slab cut back. Personally, I'm not a fan of the appearance.
  5. That would be my take as well. The "bit lighter" is very small, as the endblocks shown are spruce, and by the time you consider the massive chinrest and neck/fingerboard, I think it's pretty pointless.
  6. No, the compression wave method I only use for speed of sound calculations. It's fine for frequency, but not clean enough to get a good decay rate reading. For damping, i use the lowest bending mode frequency... if it's clean. As I mentioned, somethimes there's a nearby twisting mode frequency which interferes with a clean measurement. It doesn't ring well, and can sound like a dead slab of wood. Whether a dead-ish ring is due to this mode interference or actual high damping, I wouldn't worry too much about it in maple. The back is far less important than the top regarding what happens in the critical higher frequencies. My primary reason for avoiding slab-cut wood is that it is significantly more prone to shrinkage and cracking. If you really want to use it, I think it is important to make sure it is extremely well seasoned... or moderately torrefied. If you want to get the absolute maximum total sound out of the instrument, I'd still want a quartered back.
  7. Yes, for varying off-quarter angle. But Marty's plot is for varying from the longitudinal grain direction to 90 degrees, and you have to guess if the 90 degrees ends up at the radial or the tangential direction. I would also make a distinction between strength and stiffness, as they aren't interchangeable.
  8. It may well be correct... for the type of wood tested and the direction of the angle tested. But it's not complete. Importantly, it doesn't mention which plane the "angle" was varied in. We don't know if the 90 degree angle represents tangential strength or radial strength... which is the point of discussion here for slab vs. quartered. And I'm sure it varies a lot between different types of wood.
  9. I have no doubt that well-seasoned slab backs can look good, sound good, and live a very long time without problems when properly cared for. But the fact remains that slab-cut is significantly weaker than quartered, and changes dimension more with humidity as well. Quartered backs can also look, sound, and survive fine too... I just think there's less risk of a problem, like an accidental drop leading to a soundpost crack, so I choose not to use slab backs. Maybe I'm too careful about these things, but I don't see any downside to being this way.
  10. I agree that this isn't a profitable project. But I don't see that much in the way of getting it into functional condition if you just want something to play. A few seams to glue up, bridge and setup, and fiddle away. There could be non-obvious issues, though. Who knows what's inside.
  11. I'm not a fan of slab-cut backs, and have never used one. Slab is not good for shrinkage and cracking. But if it was very well seasoned (or torrefied), I might be tempted if it looked really nice. The dead-ish ring could be misleading. Fairly often I come across a wedge that doesn't ring well, due to some combination of the cut or grain that messes up the mode of the wedge that we normally listen to for the ring. Usually there is a twist mode very near the bending mode, and energy gets transferred between them. That type of deadness will disappear with carving. Or it could be high damping... in which case I would expect perhaps a bit less ringy of an instrument. That might be desirable or not, depending on what you want.
  12. No, I haven't tried that. I wouldn't expect anything transformative, based on what I noticed with chinrests: \ No chinrest => chinrest = fairly significant difference in the lower frequencies. Centermount => sidemount = small change, just in the very lowest frequency range If I ever get around to testing other edge masses, I'd use a spool clamp. That's what I use in some in-process testing when I don't want to be bothered clamping and unclamping a chinrest. If there was a golden zone to add mass, I'd want to glue a weight to the inside of the rib. But I don't think there is such a thing.
  13. Yeah, I'm sure it's heavy and stiff. But the point was to illustrate the echo effect. Perhaps it would be closer to the "empty barrel" sound if you used a 55 gallon drum for the body.
  14. Please don't go there again; we were just there for way too much time.
  15. "Empty barrel" works for me as a description. Others might call it "hollow" or maybe "tubby"... although tubby means something slightly different for me. I'd say it implies a sound echoing around inside, and not coming out directly. Maybe not really happening like that, but giving that impression. It might be actually due to thin plates acting like a mechanical echo device. Like this metal can:
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