Tractrix squawker horn for the Belle and Khorn

[Good2BHome]

Al,

Look at this site:

http://www.emachineshop.com/

I have not investigated very much, but added it to my "Favorites" a few months ago for future reference

Mike

[Al Klappenberger]

Guys,

The http://www.emachineshop.com/ site looks interesting. I am going to look at their drawing program. I am comitted to the local place to make the parts, at least for now though. As it sits now I think I should be ready to build these by April or so.

Al K.

[tigerwoodKhorns]

AL,

I read the Edgar article and have a question about mating it to a Klipsch midrange driver. Edgar designed the throat to be 2" x 2" to mate to a 4" driver. When he went with a biger driver, he cut the horn down, effectively opening the mouth up to mate with the driver. Isn't a transition length of 3/4" to go from ~1" to a 2" x 2" opening (over 4 times the area) abrupt?

Why not extend the horn out to a smaller throat to mate up to the Klipsch midrange driver? The Volvoteer website has a spreadsheet to do so (I have not played with it yet). If you stick with the 2" x 2" opening, what driver (that is currently available new or used) would you recommend?

I also noticed that the midhorn has an efficiency of 105 db using the JBL LE-5. Assuming that the Klipsch midrange efficiency is 104db (and I am only assuming), will your crossovers allow for fine tuning (I am assuming that I am really splitting hairs here).

Chris

[Al Klappenberger]

Chris,

The horn was designed to have a perfect tractrix area expantion from 1 inch round to 1 inch square and then on to the maximum mouth size I could fit in the Khorn. Remember that my main "thing" is computer programing for engineering stuff. It was very easy for me to write a program that utilizes the tractrix equation and iterates for a perfect square throat. The program is not a "spreadsheet". It was written in ANSI "C" then "compiled" to an executable (.exe) program that runs directly from the DOS command line. I didn't bother to make it fully Windows style as it was for in-house use only. The horn was designed with drivers like the Altec 902 in mind and with adaptors allow it to use the K55 screw-on standard.

Al K.

[Al Klappenberger]

Chris,

The sample run of the program below shows the design of a horn with identical

mouth dimensions as the one in Bruce's article but taken down to a 1 inch

square thraot, then down to a 1 inch round throat. The Fc is computed by

calculating the equivalant exponential horn cutoff that has the same expansion

at the throat. That was an assumption and it seems to be valid.

Top and bottom piece length=16.57 In. ** Angle=27.9 Deg.

Mouth dimensions = 9 x 18 ** Tractrix horn Version 1.5 **

dim X W/2 Height H/W Area ** ALK Engineering **

0.00 0.500 1.000 1.000 1.000

1.00 0.442 1.483 1.677 1.311

2.00 0.438 1.966 2.246 1.720

3.00 0.461 2.449 2.656 2.258

4.00 0.506 2.932 2.899 2.965

5.00 0.571 3.415 2.993 3.896

6.00 0.657 3.898 2.964 5.125

7.00 0.770 4.380 2.843 6.750

8.00 0.915 4.863 2.656 8.904

9.00 1.101 5.346 2.428 11.772

10.00 1.339 5.829 2.176 15.613

11.00 1.648 6.312 1.916 20.799

12.00 2.051 6.795 1.656 27.880

13.00 2.592 7.278 1.404 37.723

14.00 3.338 7.761 1.163 51.809

15.00 4.432 8.244 0.930 73.071

16.00 6.290 8.727 0.694 109.778

16.57 9.000 9.000 0.500 161.998

Square throat to 1 In diameter driver adapter thickness=0.86 In. (Fc=285 Hz)

to end * Square * File * Throat to mouth length=16.08 In.

Input new length (mouth to 1.0 x 1.0 square throat In) >

Al K.

[jwc]

Al, I have a few questions for you. I apologize in advance for taking up your time.

1. Would it be feasible to use your trachorn in combination with a Cornwall? For example: Just disconnect my K-57 and use your trachorn on top of the corn box with a K-55v or K-55m. I would still use the K-77 and K-55E drivers in the Corn box.

2. If so, what are my network options. I currently have a B-3 and want a new network all together for this combo. Would an ALK B-network work with a change in the mid frequency to 400Hz (while using the trachorn and a K-55)? Also, would there be a way to make the new network convertible to a crossover frequency of 600Hz in case I wanted to go back to using a K-55/K601 (not K-57). What impedence would the K-55 need to be. Maybe there is only one impedence available for this model. What impedence would an Altec 902 need to be?

3. How do you mount this on a motorboard in a new box. I have read the website and this thread. It appears that the front of the horn doesnt mount but rather fits in a motorboard opening of 18 x 8 ¼ inches. There appears to be brackets on the top and bottom of the horn used for mounting. The brackets are set back ¾ inches so that a ¾ inch motorboard will allow the front of the trachorn to be flush with the front of the motorboard. Is this correct?

4. Can it be painted inside the horn w/o any acoustic changes?

5. Your schematic on your website shows a depth to be 14.362 inches from the front of the trachorn mounting brackets to the back of something. Can you explain the back of your trachorn? Is there some sort of mounting bracket (L-Bracket) there too? Is this picture including a driver on it?

jc

[Al Klappenberger]

JC,

The Trachorn should work with the Cornwall fine using any network used with that speaker. The bigest problem will be getting the cable through the back if you mount the horn outside. I doubt if it will go inside.

You are correct about the ounting. It is designed to go inside a hole in a 3/4 inch baffle (motor board). It has a flange on the top and bottom with screw holes to hold it.

The length dimension given is from the front of the horn to the throat plate where adaptors will convert it from a 1 inch diameter round throat to whatever. The adaptor shown is for the K55. It's length is NOT included in the given dimension. The driver also makes it longer.

AL K.

[dhsettim]

Hi Al, always interested in your posts. Maybe you have covered it already but what do you see as the advantages of your tractix horn over PWK's K400 horn? Or in other words why did PWK choose the K400 horn profile ( whatever it is)? best wishes, tim

[Al Klappenberger]

I think the short answer to this is the progress marches on! The K400 horn is an old design. Many people (including me) have replace them with Altech 511 and 811 horns and noticed what an improvement it makes in the realism of the sound. Not everybody can do it becasue of the woodwork involved. I am hoping to make a drop-in replacement available.

Al K.

[Deang]

Al, you're a dog. It took an email from J4knee, and a trip to your site get a freaking update on the thing!! Awesome work Al.

[lwhaples]

Hello, Interesting thread. How do I get to the site?

Larry

[Deang]

http://www.alkeng.com/trachorn.html

[Al Klappenberger]

Guys,

since somebody revived this thread, I'll add some news. I just got through talking to Bill Martinelli on the phone getting all the details straight on the horn. He is already starting to make the first one. It won't be a very long wait now! He has a few ideas to improve it too. He's already figured out an easier way to make it compatable with both JBL and Altec drivers without adaptors.

Al K.

[sunnysal]

How much will they cost?

It looks like one would only be required to make a new front board for the klipschorn top hat, right?

Why that particular expansion, on one axis and not an altec 311 or TAD 4001 type expansion?

It looks like there might be a risk of diffraction artifacts from the mounting of the tweeter, no?

It looks from the response curves that the frequency repsonse of the altec horn was not as good as the k400 horn from 500-5000hz, am I reading wrongly?

thanks Al, interesting project! regards,tony

[Al Klappenberger]

Guys,

It's looking like the price of the Trachorn will be ROUGHLY $700 for a set of two horns. This WILL include a completely new front baffle assembly WITH grill cloth and a tweeter mounting bracket for the K77 or the Beyma CP25. It will NOT include shipping cost. It will be drop-in with no woodwork necessary.

Al K.

[jwc]

Al,

I can't visualize the "drop in" bracket. I have read your site and well aware of your proposed dimensions of the trachorn. I also know how to mount it individually.

Was the "drop in" feature only for the Khorn and the Belle?

Is this to look similar to what you did to your Belle?

Will a grill be necessary to make it look esthetically pleasing?

Will I just need one hole to put in the Trachorn and the K77?

Below is the rough estimate of my HF section of my new cabinet. The 23 3/4 X 10 is the INTERNAL dimensions of the HF section. So will this 2 hole side by side option work or will I need one hole for your "drop in" feature? I didn't plan on using a grill. I wanted to paint your horn black. But it would have to look good.

jc

[J.4knee]

If you look at Al's dimensions the drop in baffle he talks about is for only Bell Klipsch and Klipschorns. You cannot drop in a baffle for La Scala's. You will have to make a new horn cut out. It looks like the K-77's will also fit in the La Scala's HF section but it would have to mount vertically vice the traditional horizontal orientation currently used. From what I have read the best option for La Scala owners who wish to peruse Als new horns is to mount only the ALK Trachorn in the HF section and then either mount your tweeter of choice in the top of the bass bin or in a separate enclosure on top of the cabinet. It would seem to me this would also be an optimum time for those inclined to put ES networks their speakers to do so as well. (Jeesh I should bill Al for endorsements.) I have no experience with wood horns other than they improve the aesthetics dramatically but after communicating with Dean these bad boys seem to be pretty reasonably priced as well. Man if I can swing this, and it would take some time to acquire the disposable cash to do it and then do the ES move as well I will have to ask AL for his SSN for tax purposes!

[Daddy Dee]

Al,

That's quite a user friendly mod, almost turn key. Appreciate the care you are putting into the project.

[Al Klappenberger]

JC,

your cutout dimensions are correct. That will do nicely. I do expect to offer the hron seperately without the grill frame for the LaScala.

The new grill frames will be made to fit directly into the Klipschorn. The new grill for the Belle will require raisers like I did my speakers to fit the Altec 811 horns in them. The height of the frames will be identical between the Belle and the Khorn, so the raisers will simly lift the top section of the Bell so it's equal with the Khorn. The width will be exactly made to fit each of the two speakers.

Al K.

[Al Klappenberger]

JC,

Here's a scale drawing of the Trachorn in the LaScala with the K77 to the right (also to scale). Mounting the K77 vertically is actually a better way I believe.

Al K.