Quote:
Ilpo wrote:
 About directivity; imagine you have two radiators for the same signal. Given that the radiators are identical, on the axis of the pair the radiated signals are in phase. Move your observation point sufficiently off axis so that the distance to the radiators is no more the same. At some frequency the path length difference is half wavelength and the signals cancel. You have first null in your radiation pattern. At very low frequencies the wavelength is so long that a small distance between radiators means practically nothing in this respect. (Example 100 Hz, 3,4 m wavelength, speakers are 0,5 m apart, at 90 degrees off axis the difference is still 0,5 m which is about 1/7 of wavelength.) Imagine you have only one speaker and do the same thinking. As the size of your radiator now is the size of your drive unit, this phenomenon does not happen (or to be exact, it happens but at much higher frequency, and then we are observing radiation from the opposite edges of the drive unit).
What if your speakers are not identical? The differences in the phase response mean that even on axis of the pair the signals are not in phase and the main lobe of the radiation pattern will depend on frequency.
So, you will hear interesting responses.
You will find the graphics on any acoustics textbook.
BR,
Ilpo |
This is correct. I however would not use two identical speakers for a single channel because the sound will not be even over a number of seats. I certainly would not use two speakers for the center channel where dialog intelligibility is of the upmost importance. Comb filtering does add diffusion or the sense of spaciousness, but this works at the peril of clarity. You would be far better off just using a single speaker per channel IMO