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Trachorn plans?


cscmc1

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Is there a published plan anywhere online for wooden Trachorns? I can't afford (and don't need) the ones specifically designed to sit atop K-horns, but I do have access to woodworking tools to try making my own. Any assistance would be greatly appreciated!

Chris

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you can look at Bruce Edgar's mid-horn articles over at Volvotreter's pages and there are on-line tractrix calculators.  If a horn had two flat angled plates then a trapezoidal jig would be cut for mouth and throat heights
and marked along its axis from the throat.

then one would divide (I think) the height of each mark along along the expansion into the cross-sectional area at each point to develop the sidewall curves making a cardboard template.  A horn for cone midrange might be easier to do (?).  

Bruce Edgar truncated a 250Hz tractirx for LE5 back from the mouth a bit and used 2: 1 aspect ratio for mouth - it measured pretty good and needed a slight gap of driver from throat plate to alliviate peaking near cutoff.  (also there can be Z interactions with 1st order highpass)

conical horns seem popular today but might require lower xover or multiamping/contouring (?)  a Unity type could be compact and concentric. (look for Cowan's DIY Unity horn) and around 100dB

Volvotreter's pages http://www.volvotreter.de/

Cowan's pages http://diy.cowanaudio.com/

FWIW here's a few graphs of cone driven horn http://www.audioasylum.com/forums/HUG/messages/117396.html

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I am not sure what your requirements are other than the horn should have a tractrix flare. So my recommendation may be off the mark.

One possibility is to see what tractrix horns are available from Klipsch. They have used them in a variety of applications and one may work for you (whatever you bandwidth and other requirements are). At this point I don't know the relative cost and I assuming it would be cheaper than than some of the alternatives you suggested (since Klipsch has built these in relatively larger volumes).

This is especially true if the horn is hidden and does not need the craftsmanship for the cosmetics. IOW, is fiberglass okay?. I also don't know if Klipsch is willing to sell them individually or whether it would be as a "replacement" package that would include the driver also.

The advantage to this solution is that the horns were appropriately engineered. There are probably some hidden tricks that need to be incorporated in the design and construction. Knowing the rate of flare may be insufficient. They have the knowledge, experience and the measurement equipment to get it right. I am skeptical whether some of these other outfits or a DIYer could sweat out these details and refinements.

Good Luck,

-Tom

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