Was reading the patent summary and other information on Geddes. Trying to relate to what I think I hear. When I measured horns in the past, they showed very high IM distortion. I guess I am making the bridge that the HOM issues (reflections/refractions) are causing the modulation. At least that's what horns sound like to me. If refractions are the evil problem, how come most PA horns have sharp discontinuities in them? Does not make sense to me. Dispersion more important than distortion?
Anyone wiser than I, pipe in here.
Taking some of his ideas, what if you took a big block of fairly high density absorptive material, like compressed fiberglass, Celotex etc., cut a cone out of it, then put the very low density foam as the good Dr. recommends in it.
Could you get an absorptive horn with the added HOM suppression in the path?
Yes, Celotex. I still remember a very good sounding, very large single driver horn made with it back in college. I was going to play with it but it looks like you can't get it anymore.
The other comment in the paper was talking about how a compression driver relies on a refraction in the throat to set the initial wavefront, but it does cause issues. Would thin not suggest a dome or ring driver to be useful for a hi-fi transducer? I have never seen a good cross-section of a quality CD and horn, so I am guessing a bit.