Don Noon

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About Don Noon

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    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. 1) Probably. 2) I can't tell from here. If you can take a full breath of air and sink in fresh water, you're unusually dense.
  2. If you're making a Titian model (approx. 353 x 206mm), then 135.9g might be good... if you're making a solid-body electric version. If it was me, I would not go over 100g for that size. Maybe a little higher for extremely dense wood.
  3. Thinly built Strads I would call compliant, where higher bow speed and lighter bow pressure works best. Thickly built Guarneris I would call resistant, where higher bow pressure can be used. It's technically more of an impedance thing, but I'm using more common player terms.
  4. This isn't rocket science. I know that the method I use gives me adequately consistent results for what I want to do with it. I'm not writing technical papers, just trying to make better violins. Here's response plots taken 3 days apart, which shows that the 5-year plot above is vastly different. A few dB here and there is no biggie.
  5. Three huge factors enter into deciding if 385Hz M5 for a back plate is high or not: What size model is it? What is the weight? What is your aim... compliant or resistant character? 385Hz is high for what I normally make, but my last violin was a small (352mm) model and the back plate was 389Hz at 95grams. I generally pay more attention to the weight, and less to the Hz.
  6. It CAN be done, as each hit seems to have enough data for Audacity to generate a response plot. I haven't and won't bother with the academic exercise to look at each hit, as I know there is some variability, which is why I only do a plot of a lot of hits to get a much more consistant result.
  7. And/or damping decreasing. I will be regraduating this instrument as well; with A0 remaining the same and everything else increasing, the G string seems to be out of balance and needs some more depth. Plus I just like messing with stuff.
  8. The sound from all 90 hits are selected in Audacity, and a response line is generated from the whole thing. Whether that is "mean" or "average" or whatever, I don't know what you'd call it. Yep. Humidity differences could account for some. The RH has been moderately low here lately; I don't know what it was 5 years ago when the other response was taken. I never met Carleen Hutchins. I still had a day job during her most active years, and she died the same year I made my first violin. I have a lot of disagreements with her technical approach.
  9. Fingers aren't the best thing for plate tapping, as there's a heavy hand and arm attached to the finger, and the plate moves around a lot. It's plenty good enough for just getting plate mode frequencies, though. I use a 5g "hammer" with a vinyl cabinet bumper on the end for tapping. It's overkill for plate frequencies, but I have it for damping measurements, where the test piece has to be held at a consistent distance from the microphone. The amplitude variations (see how much Davide's plates move relative to the microphone) don't matter for frequency, but totally mess up damping calculations. Since I have the hammer, I use it for plate frequencies as well.
  10. Each line is a single test, and each test is a compilation of 90 hammer hits with 9 microphone locations. Generally I don't see much more than 1 or 2 dB overall difference between tests, although some peaks can vary locally a bit more. The A0, or air mode, is mostly controlled by the air volume, F-hole geometry, bridge height, and gross structure stiffness. I would not expect those parameters to change, so the amplitude would not change. However, I should admit that I do NOT have a great theoretical explanation as to why the rest of the response curve changed by such a large amount. Damping is about the only thing that could change that much, although this level is unexpectedly huge. As I mentioned, there is still a chance that a variation in my computer could be at least partly responsible, although I can't explain that one either, and why the result isn't more screwey than it is. I have had some computer issues that screwed up the measurements in the past, but the abnormalities were immediately obviously screwey, and resolved themselves after restarting the computer. I use a very light (1.2g) hammer to whack the bridge, and it is made of spruce so as to not damage the maple bridge. As you might expect (and as intended), the spruce has gotten significantly chewed up from years of use, therefore the impact is not as crisp as it was when new, therefore the high-frequency content of the impact energy is not as high as before. Such are the compromises of uncalibrated garage research.
  11. Sure. And since this is a sample of one, and my computer isn't a calibrated piece of laboratory equipment, there is also a non-zero chance that there's something different in my computer equalization curves or some such thing like that. But for now, it looks pretty real to me, and my ears tell me it's a better violin than it was before. A0 = air mode = strong resonance around 278 Hz. Dropouts = dips in the response amplitude Hammer frequency = I have no idea what you're referring to. No, all wood is NOT naturally dried. There's kiln drying, and then hydrothermal processing at even higher temperatures. Currently, the only naturally aged wood I use is for linings, so I can bend it.
  12. All original fittings and strings, except for the E string. Impact measurements don't read the strings anyhow.
  13. The problems I have had with trying to objectively measure how a violin's sound changes after construction have been numerous... I haven't been building for very long, my oldest ones are usually modified several times, my measurement techniques and equipment have changed over the years, and often I don't get to see my violins again. I just got back one of my fiddles that has been on consignment at KC Fiddles for 5 years. It is one of my few instruments made with totally naturally aged wood, not hydrothermally procesed. It was also the last one I made that way, as it seemed significantly less lively than ones I made with processed wood. My measurement techniques and equipment are about the same now as they were then, so I think this is a very good view of the acoustic differences over 5 years, probably with very little actual playing (but not zero, and likely kept tuned). What I observe (not in any particular order): 1) Resonance frequencies are all slightly higher. Could be the wood getting a bit stiffer, or humidity cifference. 2) A0 amplitude is about the same. I would be suspicious if this was significantly different, as it is far less sensitive to changes in the wood. 3) Throughout almost the entire range, everything is stronger, with many of the dropouts filled in. 4) At the highest frequencies (around 4kHz and above), it is about the same. My "hammer" surface is quite frayed after 5 years, and this could contribute to the effect. Before taking the impact spectrum, I played the fiddle and my impression was that it was far better than it had been as far as liveliness and response. Yes, sound recall over 5 years is highly suspect... but I have a reference fiddle or two that have been around for comparison for all these years. Again, this is a fiddle with NORMAL aged wood, and it was already a few decades old when I made it. I would not expect processed wood to change as much, as it would likely start out more like the 5-year state. And newer wood would likely change more, starting out deader. BTW, KC Fiddles retail shop is gone, but Michael Richwine is still alive and downsized the operation to his home.
  14. The first plot was at far too low resolution (size 512). The second one is at a more reasonable 8192 setting. You don't mention how the plate is being held, tapped, or where the microphone is positioned. All 3 of those things are critical to highlighting specific modes.
  15. I think there is a higher tendency to carry forward thngs that are more interesting. "Reinforces certain frequencies and provides better resonance" is more memorable and fun to repeat than "probably doesn't do anything; nobody really knows," even though the latter is most likely the truth.