Duplex W/Tractrix Horn???

[RonSSS]

Has anyone thought about replacing either the multicell or Mantaray horn in the center of a duplex speaker with a nice round Tractrix horn?
I modeled such a horn with some software from Sonicdesign and came up with a short horn with a cutoff of 750 hz. It ends up to be 4.9" long and 5.7" in diameter at the mouth. This should fit the 604/904 just fine.
Comments?
Ron

[eibei]

Hi Ron:::

Does the 750 Hz cutoff indicate a crossover in the 1000 to 1200 Hz region?

If I would not be impossing - I would be intersted in Tractrix Horn for my Altec 288's. The crossover frequency should be 500 Hz.

If there would be a charge - I would be glad to pay it.

Thank you in advance,

Lynn

[RonSSS]

I really don't know if a 750 hz cutoff would require a crossover at 1000 to 1200 hz. But it sounds correct.
For the Sonicdesign web site, go here:

http://www.sonicdesign.se/horncalc.html

I was using the demo program.

Ron

[billfort]

Very interesting Ron. Some of the best sounding midrange horns I ever heard where round and used the tractrix curve (Edgar salad bowls). I've never taken my 604s apart so don't know how hard it would be too attach a round horn. I suppose a horn flair could be turned in wood but I suspect it should have as small a finished outside bulk as possible to fit the appropriate internal curve or it would be in the way of the woofer. Maybe ABS (like used by the Oris horn) or fiberglass over a turned horn flair plug?

Intriguing idea - as long as it's reversible if it sounds ******.

Billf

[jmarkwart]

Ron,
Excellent idea! I'm interested. I agree with Bill that tractrix midrange horns sound more natural than other curves. A good rule of thumb has been to allow at least one octave above horn cutoff with a 12db/oct slope to minimize throat non-linearaties near cutoff - so a 750Hz cutoff should work well with 1500Hz crossovers. Anybody know how difficult and how reversible such an horn swap experiment might be?
Jeff

[Jim D]

I hate to be the fly in th ointment, however the round tracktrix although it may load just fine and allow a lower crossover, will beam with frequency just like an exponential. The early 604-604B multicell and the later Mantaray horns were sucessfull in distributing the higher notes across a wider pattern. The C-D-E-G eggcrate multicell was an attempt that was not nearly as sucessful. From a perspective of someone who does not want to always be on axis of the loudspeaker, while it may sound good, this would considerably reduce the utility of the unit. I would be interested if someone were able to apply the tractrix flare to a horn that would maintain 60-80 degrees horizontal and 40-60 degrees vertical to the upper frequencies. I have seen some Klipsch attempts that looked like Mantarays with a final rapid flare. My experience with these is not totally positive. If you have any ideas, let me know. JIm

[marcuswilson]

One thing that must be considered is the effect the horn has on the midrange from the cone. Assuming a tractix horn to be circular, it will be a uniform shade on the woofer cone. Any resonances or frequency related effects this may create would be consistent over the whole of the cone. This may create a problem at one, or certain frequencies. The Altec horn, being rectangular has a more varied effect around the cone, making it's effect possibly less pronounced.

[billfort]

Yes Markus, this shading affect on the midrange from the cone would be my concern. There is an large unobstructed portion of the cone above and below the stock horn that might help balance out the the sound. The fixed diameter (frequency?) of a round "shade" might really muck things up. Like I said, I'd sure want this to be easily reversible if I tried it.

[tillpape]

I?m building some saladbowl style round tractrix horns. Plan is to build a A7 828 bass enclosure with a diy-horn with xover at something between 500 and 1000Hz on top. I post the progress of work here:
http://www.diyaudio.com/forums/showt...&threadid=7032

there are a lot of pictures and on the 3rd page some pics of the lates version of my cherrywood circular tractrix horns. Anyone interested please feel free to email me.

Till