In Reply to: RE: Should we send a "representative" to Magnepan? posted by josh358 on October 17, 2011 at 06:40:39:
Yes, the high freq is a problem because of the small wavelength at 9-10khz and the narrow beam from the mids at that area. the combo provides comb filtering as you move your head - true head in a vice. Only works at LR4 - but that kills transients and adds gain stages to the XO.
Essentially, the difference in ear to driver distances should not excede the XO wavelength so that a normal head movement of +-5" should result in a change of less than 1/2 wavelength and preferably less than 1/4 in the difference of ear to driver distance from one extreme to the other - in the tympani that would be at a 10 ft listening distance roughly 10" * 8"/120" = 0.7" which is 13500/(0.7*2) about 10khz for the 1/2 wavelength criterion - ended up too close for me, and 13500/(0.7*4) = 5khz for the 1/4 wave criterion - where you can not go from positive to negative reinforcement by moving your head in a 10" range - that did work in my setup.
Taking Fc on mid LP to 4-5 khz while keeping Fc for ribbon HP at 9+ khz - XO about 6khz solved the problem because head movements have much less of an effect with the much broader mid beam in that freq range to 6khz.
I think the holes in the Tympani around the tweeter are supposed to prevent both bass induced damage and reduce doppler effects since there should be cancellation at that point so less (if not insignificant) of a doppler effect from the bass wave.
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Follow Ups
- RE: Should we send a "representative" to Magnepan? - Satie 11:46:55 10/17/11 (2)
- RE: Should we send a "representative" to Magnepan? - TitaniumTroy 23:07:42 10/17/11 (1)
- RE: Should we send a "representative" to Magnepan? - josh358 18:05:39 10/18/11 (0)