Skrivis - Srajan Ebaen has recently written about the "Doppler Effect" in his quasi review of the Zu Cable Druid speaker. The following is an excerpt in which he mentions the Doppler Effect.
"Conceptually, single-driver loudspeakers (this one's technically a 1.5-way) are phase and time coherent though the Doppler effect could be cited when you consider how the high-frequency whizzer cone rides atop the woofer. The day-to-day observable Doppler effect occurs with police or fire sirens. They sound higher pitched as they approach (wavelengths shorten), then successively lower as they pass us and recede into the distance. Theoretically, each time the Druids' woofers move forward, they modulate the tweeter response. Once you do the math and consider the average stroke of this 10" driver -- to calculate possible tweeter response deviations in terms of how woofer distance traveled equates to wave length -- it seems more of a conceptual than audible problem. Still, it's only fair to mention in this context and avoid painting a picture of theoretical perfection. Clearly, if the single-driver ideal were the one perfect solution, nobody would bother with multi-driver designs. The market place rather demolishes any such notions in one brief instance. As usual, it's about priorities. What type of compromises are acceptable to facilitate certain concrete gains that matter more to you than that which is sacrificed?"
Here is the link: http://www.6moons.com/audioreviews/zu/druid.html
"Conceptually, single-driver loudspeakers (this one's technically a 1.5-way) are phase and time coherent though the Doppler effect could be cited when you consider how the high-frequency whizzer cone rides atop the woofer. The day-to-day observable Doppler effect occurs with police or fire sirens. They sound higher pitched as they approach (wavelengths shorten), then successively lower as they pass us and recede into the distance. Theoretically, each time the Druids' woofers move forward, they modulate the tweeter response. Once you do the math and consider the average stroke of this 10" driver -- to calculate possible tweeter response deviations in terms of how woofer distance traveled equates to wave length -- it seems more of a conceptual than audible problem. Still, it's only fair to mention in this context and avoid painting a picture of theoretical perfection. Clearly, if the single-driver ideal were the one perfect solution, nobody would bother with multi-driver designs. The market place rather demolishes any such notions in one brief instance. As usual, it's about priorities. What type of compromises are acceptable to facilitate certain concrete gains that matter more to you than that which is sacrificed?"
Here is the link: http://www.6moons.com/audioreviews/zu/druid.html