I have a pair of BR Radia 520s. They have a 50" PM ribbon. Stereophile measured them (Dec 19, 2004). I would like to do my own measurements. Atkinson said in his write up:
I understand that the cylindrical wavefront is only a result of an infinite line array, and that in real life with a finite array, the response tapering is frequency dependent and mainly restricted to mid an high frequencies. From several sources, it appears that the best I can determine is "To achieve focus, or near–zero dispersion, which is a more stringent requirement, it needs to be somewhere approaching four times the wavelength." So that works out 1080Hz for 50", and below that there's increasing vertical dispersion. The bottom of the ribbon is 16" from the ground.
If necessary, I can measure outdoors where I can get about 30 to 40' of open coverage Would a ground plane approach be best?
I did a number of web searches, but other than general articles I did not find anything from which I could derive the right approach (a function of my limited knowledge most likely, not a deficiency of information)
"The microphone was placed 50" away from the speaker on an axis level with the midpoint of the 50" drive-unit, and this may well not have been far enough away to properly characterize the behavior of a drive-unit as long as the Radia's ribbon."
I understand that the cylindrical wavefront is only a result of an infinite line array, and that in real life with a finite array, the response tapering is frequency dependent and mainly restricted to mid an high frequencies. From several sources, it appears that the best I can determine is "To achieve focus, or near–zero dispersion, which is a more stringent requirement, it needs to be somewhere approaching four times the wavelength." So that works out 1080Hz for 50", and below that there's increasing vertical dispersion. The bottom of the ribbon is 16" from the ground.
If necessary, I can measure outdoors where I can get about 30 to 40' of open coverage Would a ground plane approach be best?
I did a number of web searches, but other than general articles I did not find anything from which I could derive the right approach (a function of my limited knowledge most likely, not a deficiency of information)
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