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K-402 in wood!

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I can not do a mold or a clay model as I have no access to originals. Klipsch dealers here have no idea about a k402 horn. I don't think pro line has reached these shores. They don't even know much about heritage line... 

 

My v-tracs are in wood. My Khorn bassbins are in wood, my tapped horn is in wood. My old squawker was in fiberglass. Although it has to more to do with the profile of that horn, it is my least favourite and most coloured horn of all.

 

I am sad to hear there are no plans. I could't find anyone who made a clone over forums as well. I hope someone comes up with a plan. It is does not look like a complicated build once you have the dimensions. It looks like a bigger Bruce Edgar tractrix until the last few inches where it has a second flares outwards... Hard to guess from photos...

You need to find someone who has 3D modeling  equipment, and a horn to make you a 3D drawing to work off of, IMO.

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How about making them with a 3D printer?

 

This discussion is why I don't believe that current 3D printers are "there" yet.  The tolerances and surface finishes aren't what I'd call "finished quality" and must be sanded smooth and fitted to the concentricity and finish diameter that I've alluded to, above. 

 

Making multiple pieces and fitting them together (because the 3D printers can't make big enough horns in one part) isn't what I'd call production-ready processes, rather a prototyping process that requires "sand to fit, and shim at assembly", which are anathemas to the very idea of production processes.  The L/SS guys will take you to the mat for this sort of thing.

 

Chris

Edited by Chris A
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How about making them with a 3D printer?

 

This discussion is why I don't believe that current 3D printers are "there" yet.  The tolerances and surface finishes aren't what I'd call "finished quality" and must be sanded smooth and fitted to the concentricity and finish diameter that I've alluded to, above. 

 

Making multiple pieces and fitting them together (because the 3D printers can't make big enough horns in one part) isn't what I'd call production-ready processes, rather a prototyping process that requires "sand to fit, and shim at assembly", which are anathemas to the very idea of production processes.  The L/SS guys will take you to the mat for this sort of thing.

 

Chris

 

Actually they can make em big enough... There was an article recently that showed they were building complete walls for buildings from 3D printers in China. Now as far as being accurate enough I don't know about normal 3D printers but there is one i read about that uses liquid, and they were making needles for catheters with it. So they can be very accurate, but i don't know about big and accurate. Also the one that was using liquid was supposed to be able to print stuff in a matter of minutes compared to hours with a conventional 3D printer.

 

Here is the link... http://www.popsci.com/new-liquid-based-3d-printer-takes-minutes-not-hours

Edited by ellisr63

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If I were to try this . . .

I'd get a big piece of paper and mark off the mouth dimensions, and the location of the driver, which is going to have a 2 inch diameter, such and such inches back.

Then draw a tractrix curve starting at the wide horizontal mouth and draw the curve until it points to the side of the driver. Then a straight line to the driver. Then start at the narrower vertical and do the same.

You'll wind up with a tractix mouth transitioning to the straight back section which will be conical.

You'll have to fudge a bit to make the final transition at the throat from a rectangular to the circular mouth.

It will be a bear to bend wood for the mouth end.

My thought is that great precision is not necessary.

WMcD

Bendable plywood?

 

yeah - now that would work for sure

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Hello fellow members. I am looking forward to build a horn in wood with K-402's profile. A clone in wood. Are there any plans or does anyone know of its modified tractrix profile. It is not possible for me to see or hear one in person where I live so I need some help from you people :)

There are no plans because it is patented. Watch the videos that Mike linked and you will understand why the mumps are critical to the sound. There is a reason why it is so highly regarded.

Your best bet is to speak to Roy as he is the patent holder obo Klipsch and can figure out a way, if there is a way to get them to your country. What country are you in?

Roy has installed 402s literally all over the world, but I am pretty sure he isn't going to help you clone or copy

one of his patents.

It is still patent infringement whether you intend to sell them or not and a patent holder can be deemed to abandon a patent if they don't seek to protect a patent when they have kmowledge that it is being infringed.

Travis

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Thanks people for all the help!

 

I am waiting for Mr. Delgado to answer my email.  I would be very happy getting the originals here if he can help me with that too. I contacted Bjorn as well and learned how he got his. So I will try that way as well.

 

For people asking, I am located at Antalya, Turkey.

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"For tractrix, it's the mouth that is the initial area.  That's how the curve is constructed--from the mouth."

 

According to Bruce Edgar (Speaker Builder, 2/81).

 

Dinsdale says to start at the throat (Wireless World March, 1974).

 

I think the confusion lies in this often made statement: The size of the tractrix horn is generated by specifying the desired low frequency "cutoff" or limit which will determine the mouth diameter.

 

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=19826&stc=1&d=1161638767

Edited by djk

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Construct the natural tractrix curve by hand, Dennis.

 

You start at the mouth...it's much, much easier to pull than to push to get the correct curve.

Edited by Chris A

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Travis,

 

The K-402 profile wasn't filed for patent within its one-year public revelation period (or the patent application was rejected), but the "mumps" were patented.  That's why Roy doesn't talk about the "modified tractrix" profile very much because the invention was not protected, but he did a Klipsch video on the mumps.  The K-402 doesn't need mumps--Roy has stated this directly--but the K-510 and other smaller horns need mumps. 

 

Near the bottom end of typical horns' FR, Roy stated that the polars collapse right before cutoff or roll-off is reached while going downwards in frequency.  The mumps spots provide re-radiation areas for the increasingly longer wavelengths to reflect off thus correcting that brief polar collapse. 

 

You can visualize the higher frequencies being formed farther back in the horn toward its throat--with the rest of the horn bell not being necessary. As the wavelengths become longer, more and more of the bell area of the horn is used until the mouth is reached.

 

Since the K-402 is so large, it never reaches its polar-beaming cutoff frequency in practice due to limitations of the diaphragm motion in the compression driver alone.  It's limited by the compression drivers.

 

The K-402 profile used in the KPT-305-MB assembly probably will have polar beaming issues near roll-off frequencies which are below its advertised 200 Hz low frequency crossover point.  The cut sheet says the KPT-305 has a -3 dB point of 150 Hz  (and a -10 dB at 120 Hz), which makes it a pretty spectacular straight midbass horn of extremely compact dimensions.

 

Chris

Edited by Chris A
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All these semantics about what to call the horn.....it really doesn't offer any insight and is certainly not enjoyable to read over and over again.

 

You could just measure the area expansion rate....oh wait, that would actually be informative. I'd be willing to wager that it more closely approximates the conical area expansion than the tractrix area expansion. Maybe it's better called a "modified conical"...like every other straight-walled horn out there :P

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The tolerances and surface finishes aren't what I'd call "finished quality" and must be sanded smooth and fitted to the concentricity and finish diameter that I've alluded to, above.
Our little printer at work is supposed to have a resolution of 70 microns. I believe that is .000070 of an inch (am I correct?) Unfortunately, it will only do a 6x6x6 inch piece. Maybe enough to try out Dave's elliptrac tweeter.

 

Bruce

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"You start at the mouth...it's much, much easier to pull than to push to get the correct curve."

 

First, tractrix is not the best solution for everything.

 

Second, Dinsdale starts at the throat.

 

Third, I really don't care at this point.
 

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You could just measure the area expansion rate....oh wait, that would actually be informative. I'd be willing to wager that it more closely approximates the conical area expansion than the tractrix area expansion. Maybe it's better called a "modified conical"...like every other straight-walled horn out there

 

Or you could trust in the knowledge and abilities of the designer of the K402 horn to give it the most accurate description...!!!

 

Maybe that is just expecting to much from some that should know better.... really sad

 

 

miketn

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sometimes it pays to mislead and misinform (especially in patents and promo material) they are not in business for our gratification.

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sometimes it pays to mislead and misinform (especially in patents and promo material) they are not in business for our gratification.

 

You obviously don't know Roy...if you think that could pertain to what he has discussed about the K402.

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you make it sound like I am calling Roy a lair? I take it the company owns the patent and if you have ever read many patents you will know that "patent talk" is most often there to mislead and misdirect the competition while offering up the absolute widest possible interpretation of the idea/design in question and application of the design. I have not looked at Roy's patents on this horn design so forgive me if I am off base but in general patents are about protecting ideas/technology. I know that Roy has shared all manner of insights with members here on the forum and aided in learning about his design work not to mention helping others her to design projects of their own.

Edited by moray james
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sometimes it pays to mislead and misinform (especially in patents and promo material) they are not in business for our gratification.

 

In promo material, perhaps, but not in patents. Intentionally misleading or misinforming in a patent is cause for revocation. (I speak as the holder of several patents, so this is not just theoretical knowledge.)

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NOT conical...straight sided.  There is a difference.  Read your Olson or Beranek.

It will be a bear to bend wood for the mouth end.

 

Yes.

 

My thought is that great precision is not necessary.

 

At the mouth end - yes.  At the throat--you're dead wrong.  On the "straight-sided" (not actually straight) areas, you need to hold tolerance. 

 

You need an accuracy similar to what Mike Bentz said, and that's pretty tight for wood unless you're using CNC to hold tolerance--and your wood better be dimensionally stable, i.e., not full of moisture.

 

I don't recommend wood as the base material for this type of horn.

Well, haruumph! Smile. I am not advocating sloppiness.

As far at the throat of horn. The 2 inch diameter driver has an area of just over 3 (actually pi) square inches. I will suggest that 10 percent accuracy is good enough. That gives you a fair amount of error. But if you're working with wood, and the panels are straight, that is easy to achieve. It is more hard to avoid!

Looking at the K-402, it sure looks conical, or straight sided from the driver to about 1/2 down the horn. There is no need to quibble about round or rectangular. In each case the area is a function of the square of the distance. Beyond that there is a flare. I wonder just how critical it actually is.

Don Keele has a couple of patents on CD horns. He has some equations with a "constant" changing for horns with higher and lower cut off. That defines the big end or bell near the mouth.

As far as tractrix. In my view it is like the mechanical drawing aid called a "French curve." You can pick a section and get just about any changing radius you want.

Roy is saying, if I understand correctly, that he is modifying the tractrix to achieve coverage control. Therefore, you have a side wall curve of various rates, and then you modify it. That winds up being not something which is subject to easy description in the math. This is no dig at Roy. Everyone loves Roy and his designs.

Again, in my view, there is a lot of ambiguity in what people might try to achieve and what the errors might mean.

If you are trying to make a conical, and it is a bit narrow at the throat, you're getting closer to exponential. Horrors!

If you are trying to make an exponential and it is not narrow enough at the throat, you're getting closer to a conical. Horrors!

If you want an exit angle of a bit over 90 degrees, you find it at the top and bottom of K-400. If you want closer to 150 degrees you find it at the sides of the mouth of the K-400.

Which is correct? Horrors on whichever you pick. The other is better.

If you build a rectangular horn with an area expansion like the circular tractrix the side walls are not tractrix. Horrors!

Smile,

WMcD

Edited by William F. Gil McDermott
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sometimes it pays to mislead and misinform (especially in patents and promo material) they are not in business for our gratification.

 

In promo material, perhaps, but not in patents. Intentionally misleading or misinforming in a patent is cause for revocation. (I speak as the holder of several patents, so this is not just theoretical knowledge.)

Well I can't claim multiple patents but I was involved in getting one for a loudspeaker. How about I say that some patents stretch as far as the patent office will allow. Reading patents is sometimes like learning a new language.

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