JohnCockburn

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About JohnCockburn

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  • Birthday March 23

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  1. it's good for sticking labels in.
  2. also, looks like your rib and block gluing surfaces could do with a bit of work, judging by the varnish leakage...
  3. Disagree. Complete waste of money
  4. Sorry, Don, that's not correct. The effect is due to the response of a non-linear system to 2 tones of different frequency. It's analogous to sum, difference and multiple harmonic generation in nonlinear optics. As the OP's spectrum shows the "Tartini" tone shows up in a spectrum, a beat note doesn't.
  5. People misunderstand the true meaning of "psychoacoustic". The word implies some kind of imagined or illusory phenomenon, but really it describes the response of our auditory system to external stimuli. These can, in some cases be illusory, but in other cases (like tartini tones) it's a completely measurable effect.
  6. Difference tones aren't an illusion. You hear them because of the nonlinear response of the auditory system. Or in your case the nonlinear response of your recording equipment (which also shows the sum tones and 2nd harmonic generation predicted by nonlinear response theory). It's interesting that we only hear the difference tones and not the other nonlinear products predicted by theory and observed in measurements as shown above.
  7. No criticism of you intended, Davide. I've seen this UVB/ozone thing mentioned in several KP articles. It's just plain wrong. UVB photons don't have enough energy to dissociate O2 molecules, the necessary precursor to ozone production.
  8. UVB doesn't produce ozone.
  9. violinbridges.co.uk is a valuable resource. Well worth the £10 registration fee to have access to measurements of lots of very nice "top shop" bridges.
  10. Actually, that didn't answer the question I asked earlier. As an example of what I was interested in, could you (for example) show spectra not only of the open G, but also of every successive G across all positions and strings? I think it would be interesting to see if there were any departures from harmonicity in higher positions for example. I could do this myself, but I'm on holiday at the moment
  11. I know that the textbooks tell us that a bowed string is harmonic. But have accurate measurements over a wide range of fundamental frequencies ever been made in order to confirm exact harmonicity?
  12. The Woodriver planes have got a very good reputation. I'm sure it'll be fine.
  13. If you don't have bench dogs you can clamp the plate lengthwise in a sash cramp, then stick that in your vice. Push wedges of scrap wood underneath the plate to stop it rocking if need be.