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Roger Hill

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Everything posted by Roger Hill

  1. does any of this really matter when a real violin will be varnished, which will change damping, Q, E etc. ? It seems to me that we can create almost any set of properties we want. The real question then becomes how can we make the composite behave as we want?
  2. Hi François: Thoroughly enjoyed the Strad article. Anything you would care to add about how the old masters reached their final arching shape would be of great interest here. Of course, we have beaten catenaries, curtate cycloids, circles, etc. to death but tell us more of what you think if you will. If is a research topic for your next book, we'll understand if you don't want to.
  3. Not at all. Our real problem here is that our city employees are simply overpaid and that we can't seem to control city owned enterprises. City utilities department has spare water, yet to get the parks watered we have to pay them whatever they ask for water, despite the fact that we own both the utilities department and the water. Head of utilities department is the most powerful guy in city government, i.e. his department has the most revenue. Have a real issue as to who has the power in the city government. Fundamental flaw in how we govern ourselves.
  4. Hi David: The concertmaster of the Colorado Springs Philharmonic (Michael Hanson) plays a 1920 Carl Becker violin. It is plain blond, no color at all added to the varnish that is apparent to me. Only one in the whole orchestra and it is, to my eyes, simply beautiful. Based upon it, I see no reason to add colors to my varnish. The market here accepts him for many solo performances.
  5. Thanks, David. I'll experiment some with that ground. Where do you get the alumina?
  6. Very nice, David, Judging from the ff-holes, this is a GdG model. Tell us a little more about it. Thanks,
  7. Jeffrey: on page 4 of the cycloids thread there is a post by C T Dolan that is apparently a scan of some arches. Everytime I arrive at that post it crashes my computer. Have tried with Firefox, Opera and Chrome browsers. Same result every time. Could you resize those images in hopes that they will be better behaved? Thanks
  8. In these days of looming inflation, you better buy all the snake oil you are likely to need for the foreseeable future......
  9. Except that you would be wrong to expect exactly where it could be... you did not know both the position and momentum Except that you would be wrong to expect exactly where it could be... you did not know both the position and momentum exactly at the earlier time... That was my point....when classical notions lead to conflicts with what the wave function is telling you, you are forced to give up some of your classical notions, causality being among the first to go.
  10. You're stretching my memory 46 years to my study of the uncertainty principle. Unlike old violin wood, my wooden head is not becoming more elastic. IIRC, the pre-ringing in the wave function was what lead us to question causality, i.e. the wave was indicating some probability that the particle would be somewhere before it could be there. With the DACS, the input of a square pulse into a non-oversampling DAC will output a square pulse starting when it should. With the oversampling DAC, a square pulse input results in a gaussian-like output pulse, but with pre and post pulse ringing in which the small pre-pulse squiggles overlap backwards in time.
  11. Perhaps my memory is faulty, but IIRC, "Gibbs Phenomena" is the name given to the wiggles on a Fourier transform that describes the little wiggles at the beginning and end of a square function. Correct me if I'm wrong.
  12. Don't think so, just looks like ordinary gibbs phenomena on a Fourier transform.
  13. I can't imagine that, John. The da conversion ringing distortion is non-causal. I can't imagine that in a violin. I can imagine all sorts of wierd energy transfers from mode to mode, but causality just has to be there for a violin. Post impulse ringing I think is part of the non-causal ringing. Sorry, everybody, sometimes you are overcome by the passion of the moment, even obsessively so! :)
  14. There are d/a converters and then there are d/a converters. Two types are most popular. What I prefer is "zero oversampling" as they seem best with dynamics and an impulse in produces a clean impulse out. On the other hand, there are numerous oversampling schemes which attempt to interpolate between the actual data points on the cd. Some think they give a smoother sound, but I think they introduce some digital hash. This is most readily seen as a pre and post ringing when an impulse function is input. Such ringing may be quite high in frequency (i.e. above 22kHz) and not heard by old guys like me. I think it still causes the edginess that makes the vinyl crowd to dislike cd's. I personally have a large collection of vinyl that I never play, just too much trouble to keep it clean so that you aren't annoyed by clicks and pops. Again, you pays your money..............and if you are addidted to vinyl you get your vinyl and equipment from a pusher, not a dealer Maggies lose a bit of their ambience if you take away their back wall. They are dipoles and depend on that back wall to add the reflections that make the music seem as if it is "live"
  15. So at least here you are only concerned with phase shift at the crossover points. Do you think that within the signal there are frequency-dependent phase shifts in one of the ranges? Not just at the crossover points, things have to sum properly over the entire audible frequency range. Not difficult when you are well away from the mid range and effectively only one driver is really being summed. If you mean phase shifts of the signal on the cd, god only knows what went on in the mastering and mixing of the channels to make the source signal for the playback system.
  16. I Have the Klipsch Forte speakers which have horn tweeter and midrange, 12" cone woofer plus 12" passive radiator for bass. My transient perfects are a three way system I designed using Scan-Speak drivers, 1" dome tweeter, 5" cone midrange, 10" cone woofer. Transient Perfect designs with cone drivers and passive crossovers are a particular problem because the drivers must be offset relative to each other in order to get the sound arriving at one point (10' away in my design) at the same time for all three drivers. That makes cabinet design difficult, particularly if wife approval is required. Note there is sound delay due to the offsets plus due to the roll-offs of the crossover components. The real attraction of horns is that they produce very high spl for the input voltage and dynamic range is incredible. Normal drivers (cones, dome tweeters, etc.) suffer in transients due to their lack of sensitivity; A sudden surge in power heats the voice coil, resistance goes up and the coil heats, increasing the resistance and the thing just does not reproduce the change in spl associated with a transient. This is worst for the tweeter, thus taking the leading edge off of transient signals, so you have a non-linearity to deal with. Horns do transient spl changes spectacularly well. However, the great lengths of horns make it very difficult to use spatial offsets to properly create a transient perfect combined output. Your only reasonable approach is to use a digital crossover and separate amps for each driver, a new level of PITA. Further, tubeophiles object to having opamps between them and the source of output signal. Finally, electrostatic earphones give a reference to HiFi nuts as to what music actually sounds like as only one transducer is needed for the full range of music frequencies. There are no delayed signals to try to properly sum. You pay your money and you take your choice as to your favorite forms of distortion.
  17. No contests, just different experiences, interests and points of view about it all. Gawd knows I couldn't argue with Michael about anything having to do with violins.
  18. She is truly amazing. One of her first recordings was "Tribute to Sarasate" for which she played the Amati that she was carrying when the train door closed on her. In the opening bars of the Carmen Suite, she makes the Amati produce a low, smooth growl that any del Gesu violin would be proud to claim as it's own. The accident she was in cost her part of one leg. She plays leaning against a tall stool. Having had the chance to talk to her for a few minutes, and stand in line observing her for more than ten minutes in order to buy a cd, My observation is that the personality displayed on the video is who she is, even at ten at night, having just completed wonderful perfomance of the Beethoven. Since she is from Chicago, I suspect that Michael Darnton knows her well.
  19. Yup, just like split locating pins and beestings are wasted on me
  20. Based on designing and listening to very good audio equipment, I have to disagree with that contention. In what is called a "transient perfect" loudspeaker design, you are unlikely to hear much difference in music involving very few musicians, most of the sound for a given instrument coming from one speaker driver at a time. As the music increases in complexity and number of musicians, in a "transient perfect" design" the silence between notes becomes more distinct, transients are sharper and most notably, very low spl sounds are clarified. As an example, on my transient perfect speakers I can hear every time Isaac Stern breathes on the Beetoven concerto. On my Klipsch speakers, his breaths are just part of the background noise. This is just what you would expect when sound signals at different frequencies are not delayed by different amounts of time. The average person, who does not obsess over phase shifts in his crossovers ( ) will never notice.
  21. I am continually amazed at the details fiddle-makers obsess over that don't affect sound........corners, scrolls, end-pins, labels, colors, authentic scratches, dents and nicks, genuine imitation dirt and probably a dozen more that an unwashed Philistine such as myself is too unsophisticated to appreciate. I suppose that if that is what floats your boat you can have lots of fun with it. Think I will continue my studies of arches and thicknesses which IMO are much more interesting
  22. Why indeed? It certainly is more convoluted to have to precisely locate the pinhole so that the purfling will pass through it The pins sticking out the bottom would be a convenient way to hold the plate fixed to the bench.
  23. I don't understand why purfling through the pins is definitive evidence that the plates were glued on before purfling. What is to keep one from drilling alignment pin holes in the plates, carving the plates, gluing in alignment pins, then purfling (right through the pins) then gluing the plate to the garland, using pins protruding from the bottom of the plates for alignment?
  24. to say nothing of what will happen when all those photons come through your windows and are trapped by the CO2 molecules. Man, you're as good as roasted, well done................
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