Edgar

You're welcome. Be aware that the 58 inches includes the distance between the "foldback" nearest the corner and the center of the bass section opening on the sides of the KHorn. That is to say, it is approximately 58 inches from the throat through the 90° turn along the front face, through the 90° turn back through the "twist", through the 157½° foldback at the corner, to the opening of the bass section. Greg

Oh, no. Grey is worse than black. Stay away from colors that make things look like they are war surplus. There are faux granite finishes that look good. Also faux wood grain, but they really need a smooth surface. Otherwise, a solid earth-tone color that goes well with the wood finish of the cabinet. Greg

According to my measurements of a Speakerlab K (which I understand to be a pretty good copy of the KHorn), it's about 147 cm (58 in) internal. See here. Greg

I have been street-riding for decades, but in the past several years my riding has all but stopped. It's just become too dangerous. Granted, part of it is that I've become more aware of my own mortality as I've gotten older, but mostly it's the Suburban Assault Vehicle attitude of the drivers. As cars and SUVs have become safer and larger and more heavily-armored, the drivers have become more reckless and downright antagonistic. I don't even feel safe in my car any more, let alone on my motorcycle. The joy of riding is gone. To make matters worse, I'm a bicyclist, too. Talk about feeling vulnerable ...

I don't think that you could spray enough on to have much effect. I have heard that non-hardening modeling clay works well. And it's cheap. For the price of a can of spray-on stuff, you could probably buy a couple of pounds of clay. http://www.kitkraft.biz/product.php?productid=1754

I wonder if the Electro Voice ADH-5 ("from 1 screw-on to 2 bolt-on") adapter would work for this. Read about it here.

I just want to mention in passing that this is often true, but should not be taken as a general guideline. For example, the long-discontinued EV HR9040 CD horn uses a narrow diffraction slot, yet is regarded in "ultra-fi" circles as an exceptionally good sounding horn. As always, YMMV

I wonder ... did that horn make the VW go slower (because of drag) or faster (because of thrust)?

I may have told this story here before, but I remember being on the show floor at NAB many years ago. The noise was incredible -- it was difficult even to talk to a person two feet away. Every speaker manufacturer was trying to out-blast every other speaker manufacturer in the booth next door. I was working for Electro-Voice at the time, and one of the salespeople in our booth fired-up one of our large horn-loaded systems. It cut through the noise like a lighthouse lamp cuts through fog. It wasn't that our speakers were louder than all of the others; they were CLEARER. So I think it's a quality vs. quantity issue. Some small speakers can produce 105 dB, but they're working so hard that power compression and distortion become major liabilities. (With some small speakers, attempting to get 105 dB results in a puff of smoke!) Other, usually larger, speakers reach 105 dB effortlessly. I don't have objective measurements to back this up, but that is my subjective impression. Greg

Okay; I misinterpreted what you said in your earlier post. I thought that you were trying to adjust the length of the sidewall in some way that would cause the Tractrix curve to be followed exactly along the seams instead of along the centerline. My comment was that doing so will make some difference, but not much, overall. The seam joint problem that you mention is difficult to solve, because to do it right your cutting angle will vary throughout the length of the sidewall. Intuitively, the way shown in the 3d illustrations would be easiest -- build the curved sidewalls to the approximate size, then trim them to the final size with a large saw blade slicing through at the appropriate angle. But that's not so easy to do in practice. The only other idea that comes to mind is to cut the sidewall edges purposely too steep, so that they only contact the top and bottom walls at the outer or inner edges, then fill the gaps after joining.

If you are computing the area of a PLANE perpendicular to the horn axis, then (1) the expansion rate is NOT correct and (2) it doesn't matter. The sound waves inside the horn do not propagate as plane waves. The assumption in a Tractrix curve is that they propagate as spherical waves, but that is not correct, either. They ARE curved, though, just not spherical. So if you are calculating the planar area of a circular Tractrix along the axis of the horn and then just translating that into a rectangle of the same area at the same distance from the throat (or mouth), then you are NOT creating an equivalent horn. But it doesn't matter, because horns are very tolerant of contour differences. As has been mentioned many times before, as long as the differences aren't "too extreme", all horns of the same length, throat area, and mouth area behave similarly, in terms of loading, frequency response, etc. The thing that distinguishes the Tractrix from the other contours is the 90° flare at the mouth. As long as you maintain that in your rectangular horn, it should work okay. Greg

Search for a paper named "Subwoofers: Optimum Number and Locations", by Todd Welti, Research Acoustician, Harman International. It used to be available on the Harman site, but I couldn't find it there today. Anyway, the short answer is that the best configuration for two subwoofers is: one in the middle of the front wall, and the other in the middle of the back wall. Greg

Context plays a huge part, too. I saw "taws" in J.4knee's post above, and because "'twas" is not a commonly used word any more, I had to spend some time figuring it out.

"Each Isoclean fuse is packed separately with a thick cleaning cloth you use before installing the fuses. The gold plating is of a high quality, and with the supplied cloth, I buffed it to a shine." To gold plate a fuse -- an inherently nonlinear device that doesn't belong in the signal path at all -- and then to buff the gold plating to a shine, adds new meaning to the term "polishing a [fecal sample]"

Touché.

It's been a lot of years since I was there, but if I remember correctly there's a pristine example in the lobby of Telex corporate headquarters in Burnsville, MN.

These are some of the reasons that I feel much more confident designing bass horns than midrange horns. With 28-foot wavelengths, you can get away with some severe compromises. Not so with 2-inch wavelengths. (a different) Greg

Thanks. Not exactly a glowing endorsement! Greg

The patent office is overloaded and understaffed. My most recent patent application was filed in Sept '03, and wasn't approved until about a month ago. That's almost 5½ years, if anyone is counting. And the only reason I managed to keep the costs BELOW $20,000 was because I wrote the application myself. But obtaining the patent is the easy, inexpensive part! Defending it against a deep-pocketed infringer can be an express trip to the poorhouse. Nowadays, especially for high-tech patents, many companies opt for trade secret protection instead, and hope that somebody else doesn't decide to patent the same invention. Greg

Greg, I was just poking around your Website when something caught my eye. What are the wooden midrange horns atop the black Jubilee bass bins in this photo extracted from your site? They appear to be too big to be V-Trac horns.

Belle

I'm still refining the LaScala and Belle models. It's not like it matters, so I think maybe I'm a glutton for punishment. I revised the throat model as suggested by hulkss, and made a few minor changes in the cross-sectional area profile. These models still get the "Cir > 1" warning in Hornresp, but if you ignore that and compute the response, and then modify the areas just enough to avoid the warning and again compute the response, the differences between the two are very small. LaScala here; Belle in a followup post.

It's a tough call -- how to handle folds when the cross-sectional area changes significantly within the fold. After I developed the LaScala and Belle models, I went back to my KHorn model and changed the throat model. The overall effect was negligible. Yes, I understand. The warning says that the throat acoustical impedance becomes invalid. I experimented with that a bit and found that changing the area enough to avoid the message had no discernible effect upon the results, so the models must be very "close to the edge". That matches my experience, as well. Overall, horns are pretty tolerant of moderate changes in cross section, as long as overall length, throat area, and mouth area are maintained.

Interesting ... You and I used very different models, and even very different woofer parameters, yet Hornresp comes up with very similar results. Your LaScala model in black, my LaScala model (from my post yesterday, with Vrc corrected to 58 L -- apologies for the oversight there -- also 3 dB correction applied for the 4/8 Ohm difference) in gray: Greg Edit: K33E in both cases.

And a Belle, from here. Edit: see post 1184730.