A cure to comb filtering in line arrays
Se on moro!
Much discussion have been present on high frequency vertical comb filter effect that rises from physical separation of tweeters in a line array. Usually it is said that the center to center separation of the tweeters should be less than a wavelength, or preferably a half wavelength at the highest frequency of operation. Obviously this way of thinking assumes that the element is radiating as a point source up to the highest freq. As known, usually this is not the case and so I'm wondering if the statement for the driver c-c spacing is accurate enough. OK, there are better quality drivers out there where the radiating surface diminishes to the center of the cone as the freq rises to increase the dispersion, but this is a different story. So, my suggestion is to use drivers where the radiating area is not diminishing at high freqs. The second requirement for a high freq driver in a line array is to have the radiating cone to come down very close to the edge of the driver. I think dome tweeters are quite useless in this regard as are some planar tweeters with front plates.
So the solution: check out e.g. Visaton SC 5.9 oval full-range driver http://www.visaton.com/english/artikel/art_384.htm
You see from the vertical polar plots the narrowing lobe with freq. This means that the whole cone area is radiating up to the top end of the audio band. Also note that the surround of the element around the cone is very narrow. Now take 16 or so these drivers and put them side by side in a line array, the long edge mounted vertically. To have any bass you need separate woofers, preferably dipoles of cource
In this way it would be possible to make a line array where the gaps between the radiating surfaces are minimised and it would approximate continuous 'line source' (as opposed to line array) quite well without the comb filter effect. Another good point: no crosover needed in the critical audio range. And the best part.. the cost will be reasonable
Everyone is happy, no?