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2" 223Hz tractrix horns


Guest David H

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Is that the curve at the center plane of the horn

No. Nothing that you have seen above represents the flare at the center plane of the horn.

When drawing out the tractrix flare....after you have acounted for the "height measurement" at a particular length down the horn......the tractrix flare that was posted above IS to be used as the tops and the bottoms of the horns that will lay against the jig.

Are we supposed to use the curve as a guide for cutting the tops and bottoms of the horn?

Yes

.....is that the curve of the inside corner of the horn where the side meets the top of the horn from the throat to the mouth?

I think the answer is yes for this....if I'm picturing what you are saying correctly

I hope I'm helping

jc

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Greg I think median flair has already been accounted for, because the vertical flair and length have already been calculated.

Does that mean that the curve drawn on the graph paper is the curve of the inside joint where the top piece joins the side piece? If so, then we can say that the curve drawn on the graph paper can be used as a template to cut out the top and bottom pieces of the horn without adjustment.

Greg

yes

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Guest David H

Does that mean that the curve drawn on the graph paper is the curve of the inside joint where the top piece joins the side piece? If so, then we can say that the curve drawn on the graph paper can be used as a template to cut out the top and bottom pieces of the horn without adjustment.

I believe the above is correct.
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Guest David H

Woohoo! I get it now.

For some reason my brain was telling me that the curve was in the center plane of the horn. With this knowledge, and GotHover's trick of sanding the angles in the jig, this just got a lot easier.

I've got to go buy another sheet of plywood now.

Greg

Excellent, BTW what flair are you using? I ask because there was an error on the one I posted to this board that I modified last night.

223 HZ horn info:

Mouth internal height 12" Not to scale, Reccomend build 1/2 flair then mirror for accuracy.

Length 17.5" I also reccomend adding 1 inch front and rear of the flair to be trimmed after complete.

Throat 2"

17.5"------------------------------------------------------------------------------------------------ 12"

17" ------------------------------------------------------------------------------ 9.50"

16" --------------------------------------------------------------------- 6.95"

15" -------------------------------------------------------- 5.53"

14" ------------------------------------------------ 4.55"

13" ------------------------------------------ 3.73"

12" --------------------------------------- 3.17"

11" ----------------------------------- 2.72"

10" --------------------------------2.36"

9" ---------------------------- 2.04"

8" -------------------------1.78"

7" ----------------------1.57"

6" --------------------1.39"

5" ---------------- 1.25"

4" -------------- 1.14"

3" ------------ 1.06"

2" ----------- 1.0"

1" ---------- .97"

0" ----------- 1.0"

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Excellent, BTW what flair are you using? I ask because there was an error on the one I posted to this board that I modified last night.

Sorry, top secret! [:)]

No, actually I'm trying to fit a tractrix horn for a 2" driver into the stock Khorn tophat. JC is reviewing the calculation right now.

Greg

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GotHover

This build is great. I can't wait to run the curves tonight.

I would email you this photo but either mine or your email doesn't like the other. Can't attach in PM.

Have you considered using a 2" drill hole cutter for the baffle. That way you have a perfect circle right in the middle of the baffle. This is what I used before and it worked great.

Cutting a 2" square is hard.

jc

post-16499-13819435533122_thumb.jpg

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Guest David H

Excellent, BTW what flair are you using? I ask because there was an error on the one I posted to this board that I modified last night.

Sorry, top secret! Smile

No, actually I'm trying to fit a tractrix horn for a 2" driver into the stock Khorn tophat. JC is reviewing the calculation right now.

Greg

Nice!!!
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Guest David H

Cutting a 2" square is hard.

I have considered and have used the hole saw in the past, but it is very difficult to get dead center. so I just drill a hole big enough for my flush bit router and ride the throat of the horn. The router bit bearing disintegrated while I was cutting that one, that is why it is cut so poorly.

I am embarassed at how bad the prototype turned out, but I dont think any of the flaws will effect performance. The second one I built looks really good.

I have made numerous changes in the build, and built all of the assembly jigs, No more pocket holes etc.

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This build is great. I can't wait to run the curves tonight.

Hey JC

Are you testing in room or outside?

If outside especially, maybe you can run some Horizontal off axis curves maybe at 10, 20, 30, 40 degrees to get a basic idea of the polar behavior of the horn.

GotHover you are definitly very talented! Thanks for showing your building methods.

mike tn

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I run curves on both drivers. Remember that these driver are meant for two way and aren't meant to go down to 300Hz.

Consistencies>>>

Horn goes to at least 400Hz and sometimes below with these drivers. As predicted...the horizontal coverage drops off as you move off axis.

I measured several times with both drivers outside. I moved the JBL driver inside and continued to mess with pink noise. Outside I'm getting two areas of a dip that I don't get inside. The pink noise must be reflecting off something out there.

Anyway....in my house those two dips are gone and I get a different one at 2000Hz. So remember that when I post curves later.

Now.....I'm no pro....so if you don't trust what I'm doing...or just don't find it reliable....then go snicker somewhere else. I bet some are going to find it interesting. there are generalities that can be made here that are helpful.

The first off axis horizontally I did over and over was 15 degrees off axis. Yep....4-5K Hz...starts to roll off. The 400Hz stays solid. The next off axis was 22.5 degrees. Starts to drop in the same place more rapidly. At 30 degrees off axis......some dB is lost down to 2KHz.

The curves on both drivers look pretty similar.

I need to convert some of these to jpeg to upload. I'm not doing all of them.

It will be awhile before I'm able to "listen" for "quality".

GotHover. Your build is good....I wouldn't change the way you assembled it really. I love being able to take off the baffle to switch drivers. I also like the way you put that gasket material of the throat of the horn between it and the baffle. I never thought of doing it that way. It is cool as I can make my own baffle and put on there.

I would still consider the circle on the baffle. The holes for 2" compression drivers are 4 holes on a 4" circle. The holes need to be 1/4 and then some.

jc

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