Originally Posted by
Steve Schell
Hi guys,
I thought I had posted the original article by Dr. Smith, "A Distributed-Source Horn" on the forum in the past. I couldn't find it in a search however, so here it is. Note that Dr. Smith mentions that his design was to be used above 750Hz., even though it has an exponential flare constant of 375Hz. This is very conservative design of the old school, no doubt intended to avoid the response ripples of a finite exponential horn down near cutoff. My guess is that his design could be reworked for a 2" throat and a slower flare rate and still have a reasonably compact horn. Smith horns were built to cover different frequency ranges in the 1950s; I have seen pictures of at least one system using three different sized Smith horns plus a woofer section.
People are often confused by what looks like a rounded triangular section in the throat in the drawing. It is only there to show the angles of the "torpedo" dividers, not to indicate a solid structure.
Sorry for the crummy photocopy- not my work. I have the magazine, so if there is interest I can make better scans from the original.