|Here's some old photos I took during construction of my third and final set of corner horns in 1976. The throat can easily be seen, and for reference, the dimensions of the throat is 7 x 14 inches. I still wonder if that 1:2 ratio has any audible effect on performance. Given that these dimensions correspond to wavelengths of 1937 Hz and 968 Hz, one wouldn't think so considering the mass loading of the JBL 2205 in the region of 200 - 250 Hz.|
|Here's a top view showing the three trapezoidal pieces whose left & right edge angles defied my ability to calculate. So, the trial & error method was used. the angles at the longer edges, marked as A & B were no challenge. Similar difficulties were encountered with the top and bottom panels of the rear chamber.||These horns are of the single flare type versus the dual flare as used by Mr. Klipsch based upon a paper written by Harry F. Olson in 1938 and titled, "A Horn Consisting if Manifold Exponential Sections". In this paper, he describes up to 3 flares which is probably a practical limit despite the purity of mathematics which might shew otherwise.|
|A dual and triple flare had been
considered for these fellas but I kept running into
snags. At the top of the priority list was low frequency
cutoff. I just HAD to get as close to 30 Hz as possible.
So, that essentially fixed the mouth size and DID fix the
flare rate constant, m. The throat was essentially fixed
at 87 or so square inches for the 2205. I did consider the
smaller throat idea but this would load the driver more
and at that time efficiency was in conflict with low
frequency cutoff for first place. With the aid of a fifty
step programmable hand held calculator, a myriad of dual
and triple flares were considered to little avail. See, I
also wanted to keep the flare transitions away from the
bends in the horn. This wasn't priority three. That was
reserved for the horn's fitting through a doorway.
Well, the single flare seemed to be the easiest way out since it "fit" within the paramaters set by my obstinacy. A few years after these were built, I got hooked on computers. My first was a Tandy Radio Shack TRS80 Model III. With Lotus 1-2-3, version 1.something, it was easy to set up a spreadsheet and do all the "what ifs". But, the fascination with computers sounded the death knoll for the building of another set of horns.
|The drawings for these guys were all done the hard way. No fancy table with that device, whatever it's called, that bolts or clamps to the table. No fancy parallel guided by nylon strings and pulleys. Just a parallel my father made at Dominion Bridge, several triangles, compasses and that calculator. Had it not been for the calculator, I'd have had to refresh on my slide rule use. My dad, an engineer, taught me how to use a slide rule when I was in grade school. The teachers wouldn't let me take it into class.|
|Two "IDEAL" Woofers ?
My Afghans, Ramses & Sabrina
I have no idea what is on the ground that seems to have caught their attention. I also have no idea how I happened to be there with a camera.
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