| Цитата |
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| Если измерить КНИ на разных уровнях, то с ростом уровня искажения сначала снизятся, а уже потом будут расти |
Очень интересный и сложный вопрос, которому, к сожалению, уделяется мало внимания. Проблема сдесь в следующем: формально мы имеем дело с упругими изгибными деформациями подвеса, которые по идее не должны проявлять нелинейность при малых деформациях. Да и пороговых ограничений быть не должно. Реально - они есть. Причин тому - множество, но это уже детали...
Итог - снижение "детальности" в звучании, которое достаточно сложно предсказать по формальнымм параметрам динамика. Неким косвенным признаком может служить только Qms...
Кстати, вот интересная выдержка из интервью Joachim Gerhard:
- Many "old" paper woofers still sound astonishingly good compared to modern drivers?
- Oh, yes. We have not always went to the better. What many driver manufacturers have done the last years, is to increase the damping to make the frequency response more flat. But some old drivers, like the famous 6,5" paper woofer that Jan Paus at Seas made several years ago, (The Seas CA 17 RCY, ed. note) was optimized for low loss. So they made a compromise between frequency response and sensitivity. This driver was very good, and was used by Wilson Audio for many years. Later, in the 80's, manufacturers started to add more mass, they added more damping, and they made surrounds with high loss. That gave an extremely flat frequency response, but also a lot of energy storage. This compared, the old drivers were much quicker. They had some resonances, but you could get rid of that in the crossover. It was this run for flat response that gave a lot of modern drivers this dull, uninteresting sound. And you can also measure higher second and third harmonic distortion in some of them. If you compare the on-axis response between an old and new driver; you will see that the energy in the treble is far higher than in the new drivers. These so-called "modern" drivers often has a Qms of maybe 0.8 or 0.6. The old drivers had Qms values of maybe 5 to 7! We found that drivers with a very high mechanical Q sound more open, more clean and dynamic. And when you look at it, you find it is very simple, because they have less loss. The surround is easier to move, the spider is better constructed, they have better air flow, higher sensitivity. So a high mechanical Q is a very good indicator of energy storage behavior. This is one of our secrets. One of the many!
Маленький коментарий. IMHO - увеличение "потерь" и снижение Qms страшно не само по себе. Просто в реальной жизни это неизбежно приводит к повышению нелинейности на малых амплитудах и к пороговым ограничениям. А для головок с магнитной жидкостью в зазоре надо учитывать даже такой момент как поверхностное натяжение этой самой жидкости, которое может приводить к ограничениям на малых сигналах. Вспомните "фокус" с булавкой, не желающей тонуть в воде.