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Timbre Tones Audio Tractrix Horn
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Home
About
Contact
Timbre Tones Audio Tractrix Horn
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Cart (0)
Home
About
Contact

I used an online tractrix calculator and hornresp to design the template with the correct X-Y coordinate points for the response I was trying to achieve. I cut the template out of 1/4 inch plywood to use in the mouth of the horn.

Cutting the rings is not as easy as one would think. Since these are made out of 8/4 hardwood and several inches in width, just a fraction of a degree off is multiplied when you have 12 segments. I then put a rope around the ring and tighten with a screwdriver and a block of wood. If you look closely you can see the yellow rope. After it dries I have to flatten out the ring with a large 20 inch sander I made on my lathe and when the rings get too big, I switch to a router and sled.

I find it easiest to turn one ring at a time in case there is a catch and I need to remove a section to start over. Here is about how far I go before I start on the 2nd section and glue the 2 halves together otherwise I need help getting the piece mounted on the lathe every time I work on it.

I build a new faceplate to start on the end section and turn the last 8 inches. When the final piece is 30 inches wide you don’t want it extended out too far as it gets pretty heavy. I keep my horn walls over 2 inches thick and it gets a little intimidating to have something that large and heavy spinning in front of you.

The throat adaptor has threaded inserts to bolt the rear chamber and horn. I use a B&C 12 pe32 for this horn with a 5 inch throat which turns this into a compression driver. With a sensitivity of 110db@1w1m this thing will never break a sweat.

Measured outside on a ground plane, 3db down brings this to a 110hz horn, but in room response I am able to crossover to my subwoofer at 80db by filtering out below 70hz in my dsp, and running full range on the horns. I set the crossover at a 700hz 4th order LR slope.

Measured outside, 120hz at 109.4db, you can see the 3rd harmonic distortion is 0.011%

The waterfall plot shows a very smooth response 30 db down.

For my High Frequency driver I chose the B&C de750 tn-8 mounted to a 250hz tractrix horn I also turned on my lathe. I built these before I started working with segmented pieces and it really does waste a lot of wood, but it turned out pretty pretty nice.

This driver is good from 500hz to 18khz which starts to roll off at about 12khz. I have since made an upgraded version of this horn which is 2 inches longer and wider at the mouth and has a much better response above 12khz. You can see those measurements down on the next page.

Testing on axis to 90° off axis in 10° increments looks pretty good to me. The music from these horns just blooms outwards creating a wide enveloping soundstage with consistent presence even as you move around the room. These speakers disappear into the room with airy musical delight, with natural weight and ease.

The distortion graph looks pretty darn impressive as well. 1khz at 104db has a 3rd harmonic distortion of 0.081%. Listening fatigue? what’s that.

The waterfall is impressive showing no sign of resonance 40 db down.

My latest HF horn is segmented, made with soft maple and is a little larger than my previous horn made out of hard maple. I prefer the sound of the soft maple and that’s what I use for all of my horns. Soft maple has better damping, and a smoother sound that extends to 18khz.