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Everything posted by Edgar

  1. I was wondering the same sorts of things. Another way of looking at it is, "100 percent is (only) 3 dB". That means that driver parameters can change by a whole bunch and still yield just a 3 dB difference. And as I showed in my WinISD model previously, even a 50% change in compliance resulted in just 1 dB difference.
  2. Can't say that I did. Well, you learn something new every day.
  3. "Acid test" comes from testing samples of ore to determine whether they are gold. Gold does not dissolve in nitric acid, but it does dissolve in aqua regia.
  4. I have a 49 year old Brooks saddle on my mountain bike. I'm pretty sure that it's broken-in.
  5. At my former employer (I'm now retired), we set up a test of a dozen or so capacitors operating on the medium voltage line. These were special film capacitors designed to face 7200 VAC @ 60 Hz continuously, so we were testing them for premature failure and any changes in their performance parameters. Over the first month their capacitance changed by a few percent, and then stabilized. Now audio capacitors will never face anything like 7.2 kV, but the example does offer at least some evidence that capacitors "break-in".
  6. If you get excessive wind noise when riding your bicycle, then you must be very fast. 🙂 Old adage among bicyclists: "Anybody who rides a circular route and complains about a headwind the whole way is either very fast or has a bad attitude."
  7. I think we've established that driver break-in does occur, and that it's probably audible. We still haven't resolved whether it takes 20 minutes or 200 hours.
  8. Using the "breaking-in a pair of shoes" analogy, imagine walking for 600 hours. At 2 mph that would be 1200 miles, by which time most shoes would not only be broken-in, but worn-out.
  9. It would not surprise me if sample-to-sample production tolerance differences between drivers had more effect than break-in. For the record, that's just conjecture on my part.
  10. I get the impression that modern compression drivers are designed (at least in part) for much greater power handling and excursion than vintage compression drivers (such as my Altec 288). Do you find that to be the case? If so, what compromises were made in the process?
  11. That is torture for a compression driver! Do you also get a lot of infant mortality with this test?
  12. But does it take 200 hours at close to full power to happen?
  13. You beat me to it. We've gone from changes that are "significant" (the best word that I can think of to summarize the various claims about the sonic changes) to "a few percent". So which is it? In my experience, woofers do break-in, and the effect is measurable. Whether it's audible is in the ears of the beholder.
  14. You'll find that many of those early stereo recordings don't mix down to mono well at all, because some of the stereo content was out-of-phase.
  15. A top fuel drag motor only makes about 1000 revolutions between teardowns.
  16. I tried a little experiment with WinISD. First I modeled a K33E in a vented box. It is shown in green on the attached graphic. Then I reduced its compliance by half (equivalent to doubling the suspension stiffness), let WinISD recompute the T/S parameters, and modeled that in the same sized box tuned to the same frequency. It is shown in red on the attached graphic. A doubling of stiffness caused about 1 dB difference in the frequency response.
  17. Very little effect below about 300 Hz. Essentially no effect below about 125 Hz. As expected, given the thickness.
  18. I have noticed that highly efficient (or highly sensitive, take your choice) speakers also handle dynamics better than inefficient speakers. At least, that's how my ears hear it.
  19. Years ago we were using a FFT spectrum analyzer to check the noise floor on a piece of equipment that my group had designed. The SA showed superb noise performance, yet when we listened we could clearly hear an unacceptably high noise floor. It took a bit of investigation, but it turned out that what we heard was impulse noise (a series of discrete clicks occurring often enough that they sounded like noise) in which, by sheer coincidence, the period of the impulses almost exactly matched the spacing between the FFTs. More often than not, the impulses occurred during the intervals in-between the FFTs, so they were rarely seen by the SA. Just one case in which what we measured did not agree with what we heard.
  20. https://www.don-audio.com/Edcor-transformers
  21. I lived in Minneapolis for six years. Never heated my block. Never failed to start.
  22. Edcors are not Jensens, but offer most of the performance for a fraction of the price.
  23. If you've ever owned a pair of real leather shoes or boots, you know that they eventually break-in ... and that they also eventually break-down. We try to minimize both problems in loudspeakers and electronics.
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