Horn for LE85

[spkrman57]

Tractix horns according to Dr Bruce Edgar(and others also) are shorter than other horn designs(hyperbolic/exponential/etc).


Tractix horns also are not designed to be used to their flare frequency since at the end of the flare(mouth) ends up being 90 degrees referenced to the throat.

Simple examples:

Edgar round tractix horns:

650hz flare - designed to be used no lower than 800hz minimum
500hz flare - designed to be used no lower than 800hz minimum
350hz flare - designed to be used no lower than 500hz minimum

While the 650hz flare works to 800hz(not well enough for my ears), I found a better overall sound performance when crossed over at 1khz or higher.

Not trying to confuse things here, just giving my points of view in the hope that it might help out.

Ron

[Mr. Widget]

I wasn't going to bring up horn cut off frequency verses minimum usable frequency because it can get confusing. Since you have, my personal rule of thumb, which seems to roughly correspond with your findings is that you should use a horn no lower that 1 octave above it's cut off. Using that rule, the 650Hz horn should be crossed over no lower than 1300Hz.

Widget

[Ian Mackenzie]

The LE14a might be interesting with a 2344 and perhaps Zilch has tried this already. Try making one out of wood like others have recently posted.

But it depends on your expecations and how hard you intend to run them and your level of skills with crossovers and system tuning etc.

If you are adventurous and intent on running horns down to 650hz, propably a good crossover point for a 1.4 inch driver; a 1.4 inch driver is a much better candidate or even a 2 inch driver like the 375. But the LE85 is still fun to play with and its a nice driver.

Some horn diy fans who love wood turning use mutiple horns over limited bandwidths ie 400- 1000hz using an LE5 , 1000 - 4000hz using a 375/2440. 4000-20K using a LE85 with some eq. These are not compact affairs nor are they Waf friendly but they can perform well with careful setting up...

[dmtp]

No, I haven't heard it yet (still mocking up an XO - probably 1000Hz, maybe 800), but I had to post pics of my "salad bowl" horn. It is a 500 Hz Tractrix horn in solid cherry. In the first pic, you can see it mounted just above the LE14A in the beginnings of a cabinet. Walls of the cabinet are 1 3/8" thick (5/8 particle board & 3/4 MDF) and the speaker mounting board is at 30 degrees to the front wall. (It is lying on its back in the pic.) Cabinet was ~4 c.f. before bracing and the horn. I have yet to cut hoples for the tuning ports which will be two 3 1/2" (ID) mailing tube that just fit between the horn and woofer on either side.
The second pic shows the outside of the horn. The entire horn is 8 1/2" in diameter except for the ring 1 3/8" back which is 10" creating a nice mounting flange. The LE85 is mounted to a 1/2" piece of composit (bowling alley material that I got at the dump years ago!) which is then lag bolted to the cherry horn. (recessed hole in the horn for the three bolt heads). I intend to coat the horn with West Epoxy to create a nice smooth, shiny surface, but I'm waiting to finish the other horn before mixing epoxy.
Stay tuned!