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Anders Buen

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About Anders Buen

  • Birthday 06/03/1970

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    Oslo, Norway
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    Violin-, Hardanger- fiddle-, room- and architectural acoustics.

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  1. Interesting observation!
  2. Crossgrain stiffness of spruce and wood in general is very depedent on the grain angle. It drops fairly fast with increasing angle. So squaring up the wood makes the plate as stiff as that piece of wood can be, crossgrain. In my statistics work it seems like the crossgrain stiffness is more significant than the along grain stiffness. At least when it comes to predicting the B1- frequency. Mode 2, )(, seems to be a better predictor than the other three typical modes, #1, or #5. Mode 2 is mainly crossgrain bending.
  3. He used to have this on his website. http://www.fiddleheadstrings.com/fiddleheadstrings_web_revised_dec17_010.htm
  4. Oliver Rodgers and Molin et al idependantly developed measurement procedures for assembled symmetric top and back plate blanks for extraction of three of the elastic moduli and density, of course, based on FEA calculations during the early 90ties, I believe. Rodgers made graphs and a program for the purpose. Molin et al made graphs for the purpose. Later Tom King made an Excel sheet based on Rodgers work Both methodes were presented in the CASJ, (Catgut Acoustical Society Journal) which is open access now.
  5. This kind of data was what I originally was looking for. So thanks for that! Are the weight gain for the entire violin or just the plates?
  6. An update on the statistical modeling on free violin plates. Now I have run some multivariate regression which seems to work pretty well for the top plate data, a larger set than for the back plates. The input for the top plate modes are weight, average thickness, in some cases the density, the crossgrain soundspeed C|_, and for the highest mode (#7) also the Davis impedance, Z is used. The archeight given by the highest arch height does not enter the models, somewhat to a surprise. For the back the formulas are a bit more simple. Nonlinear regression does work for very narrow values of the input data, but just outside that, the predictions becomes non natural, even negative in some cases. Clear signs of a too small data set, especially for the more un-usual modes to note. The back plate data size also suffer from not having my n= 92 ish data points in there, as I record the tap tones for the backs on the maple, ribs and the neck in place. In spite of this, the predictions are not far from the former sets based on weight or average thicknesses alone, except for #7 in the back plate where the data and model rely heavily on Schelskes thinning experiment in 14 steps. The back plate mode 7 has very high frequencies in that study. The back plate mode 5 prediction is also probably a bit weak, only 52% of the variation in the set is explained by the used model. The prediction is lower in frequency than I would have expected. However, not far from the other simpler models. The nonlinear modelled point in Möckels data end up in the lower quadrant as well for the Strads with a slightly higher mode 5 frequency for the top. The data points up to #6 still lie close to the top = back line, just barely lower indicating a slightly stiffer back than the top for this example. The other data inputs are shown in the first graph. For the top the explained variation is from 81-95%. For the back plate the explained variation is from 52% up to 97%. However, it remains to be seen if the models behave natural in all natural input regions.
  7. I think every now an then a violin can have a harsh note, even a fine one. Maybe the better violins have fewer of these. I think it is really hard to pin a harsh note down to a given building trait. But if you find one and a violin without a harshnes, or even better, a harsh note and a non harsh one of the same violin, those could be investigated further in comparisons. The best situation would be a harsh note and a good none next to each other. It is possible to make a fiddle with no recurve to sound deep and great. Nothing harsh. Arching is in my opinion less important than graduation and wood. We know a higher arch supress the lows and give an apparent boost in the highs. High and or bad archs give instruments that behave more suceptible to changes in the relative humidity.
  8. If the instrument is stolen, and the player knows, it may sound harsh.. :-)
  9. Lets say there is a twisting mode or so in a fingerboard neck lying close to a body mode. Slight chnges of fingerboard length or thickness may give an effect on that particular mode. I think there are examples shown in my article. Or at least shared here on MN while I conducted the change from violin to Hardangerfiddle in steps. Inlcuding steps of cutting the fingerboard. I have bought e few custom made dragon hardanger fiddles from China. There is a dip in the B1+ mode and I tried to hollow out the somewhat large heads, and the dip was still there. I know the dip is related to the neck-fingerboard system in some form (also shared here on MN), but that operation did not make much change to the dip nor playability. It was some time between the before and after test, though. In general I think the longer and heavier HF nack gives a lower B1+ mode frequency, although HF in general have thinner backs. Also a possible reason. It is hard, I think, to generalize on this matter. As it is with chinrests as well, I think. It is even harder to percept the changes by playing than to measure a change using high resolution instrumentation. However, I do believe violinists can spot these changes better than a fiddler as they can and my stay longer on each note at a given frequency.
  10. Thanks for being interested! It is a while ago I did these experiments. I do have the strings lying somewhere. I think they are sort of synthetic core strings, not much different from Dominants. They are not of the steel core ones. They are less easy to play, but probably louder. The test instrument is of "high grade", thickish as del Gesu but the wood is likely to be stronger. A rather stiff fiddle. I have not tested the different Chinese strings in detail. Maybe a thing to look into. The larger number of violins tested against hardanger fiddles are mainly with mittel Domintants.
  11. The most compressed version on this is a poster from the 2013 Stockhom Musical Acoustics Conference: https://www.researchgate.net/publication/339587232_Buen_SMAC-242_Poster_A3 The article governing it: https://www.researchgate.net/publication/325392479_THE_ACOUSTICS_OF_THE_HARDANGER_FIDDLE A more recent presentation, also including some speculations on the string effect, theoretically: https://www.researchgate.net/publication/351283853_Some_aspects_of_the_acoustics_of_the_Hardangerfiddle There is a later article as well governing this presentation. However, it is very similar to the one from 2013. If you prefer to hear me talk on a slightly shorter version of the above slides (nothing on the string theory, due to time constraints) i have the presentation from the Baltic Nordic Acoustical Meeting 2021, which was a video conference due to te pandemic: https://www.youtube.com/watch?v=YVY7MsN3lZ8&ab_channel=AndersBuen
  12. The Hardangerfiddle is kind of baroque. Gut strings, traditionally, and played at a higher pitch. Shorter and lighter strings makes it sound a little weaker than a violin with Dominants mittel. Still the sound is more intense. The bridge is also different with long legs, chelloish kind of. A baroque bridge would also influence the sound spectrum, and I guess the violins were played at lower pitch. Please correct me if i’m wrong. The pitch varied with the region and instruments there, like flutes, or maybe the church organ. I am sorry that the baroque violin and fiddles are not studied more in the VSA and in general. I think this limits the insights and makes the violin acoustics subject less interesting than it could have been.
  13. Maybe pure sound, and not necessarily loud, may be weak-ish fundamentals on the e-string first position and getting support from the bridge/body hill region instead. Maybe also a sharper dropoff at the very highs. I do not have full control over the bridge body model. But higher damping there can play a role, as well as lower damping of the bridge. In vibration insulation theory, a mass spring system with a dashpot damper (viscous damping) give a stronger filtering above the resonance than does a higher damped system. The response around the resonance will be stronger for the less dqmped system than the more damped one. So a low damped bridge body system may give a clearer bridge/body «formant».
  14. The lowest graph is the interior impedance. What goes out of the instrument in the open end is the part that does not become reflected. The wavefront in a woodwind instrument or a trumpet is a «flutter» going beck and forth in the conical tube, amplified or sustained by the lips or the beating reed. If the impedence is high in the tube, less enters the room behind he tube. With a cone, less becomes reflected and more enters the room. Brass instruments have a high frequency effect you may hear in angry elephants, even sportscars or japanese street racers with long pipes as a «brassy» sound. A trumpet eg, playing loud may sound more brassy, perceived as being louder. The brassiness thing is nonlinear, caused by a sharpeing of the wavefront inside the instrument which leads to higher output of higher frequencies.
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