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I found the LEE CATENOID patent!


D-MAN

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I ran across a patent that referenced a catenoid horn, but reported that the LEE CATENOID mentioned in "How to Build Speaker Enclosures", Baedmaeiff and Davis, Sams Publishing, 1978 (but not disclosed therein) could not be found. I'm not sure that the patent office even knew it was there, being 1958 and all.

That's because the patent was owned by Labratory of Electronic Engineering, Inc. in Mass. (not LEE) as US Pat# 2819772. It's a corner horn that uses a catenoid expansion, a rare animal indeed. These were marketed in the late 50's and evidently went extinct, and I would sure like to hear a couple!

Here's the link:

USPTO

But a word of warning, you have to download some sort of "reader" from the USPTO website in order to view the pictures, which is the best part of course. Otherwise, all you can do is read the text.

But anyone interested in horn design NEEDS to get into the patent lookup anyway!

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The LEE CATENARY (I previously said CATENOID) is the tradename that the speaker was sold as. I have heard the name, but have never even seen a picture of one before, they evidently were quite obscure.

Horn afficianados are the only interested parties, I suppose. Hoped to give somebody besides myself a thrill.

...and it can only be a thrill to bonified, dyed-in-the-wool, hardcore horn-heads, that's for sure! I guess I'm finally one of those, now, because I actually got excited that I'd finally seen one!

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No, I wouldn't consider it a knockoff by any stretch, you can't patent a knockoff. It has to be explicitly different or has to be an improvement on something else.

The only 2 things that the LEE CATENOID has in common with the Klipschorn is that:

1) they both go in the corner

2) they both are folded horns

After that, they are completely separate and unrelated animals. Hence the patent on each.

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John, no, it's a "catenoid" type of horn also called a catenary, I believe. That as far as I can tell is an extreme flare rate, way more than a normal tractrix or an exponential or even a hyperbolic type.

I only have read of one other horn that uses this type of expansion, and it is meant to be placed up against a wall, that is, it's not a corner horn like the LEE one shown above.

Fact is, two inventors have determined this type of horn to be "better" than others, and because of the low number of references available, I have never heard one.

mOOn, I suppose that the design was intended to directly compete with the Klipschorn, and that could explain the corner-horn aspect of the design, but other than that, I don't see much relationship-wise to PWK's bifurcated exponential horns. Of course, if it goes in a corner, its going to be compared to the Khorn. But the inventor (I'm guessing here) probably understood the competion, though.

It also was competing against the JBL Hartsfield, another cornerhorn made at the time (which went extinct also). So this design was evidently capable (I'm assuming) of holding its own against the competition, but hearing would be believing.

Interestingly, it is abundantly clear to all that it failed to effectively compete with the Klipschorn, but there could be other reasons for this other than performance. In particular, it looks larger to me than the Khorn, so that would be a hard sell, of course.

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mOOn, one more thing, you may have a point about PWK's teachings...

The element that I see is that the LEE is also using a front-loaded horn (i.e. the back chamber is sealed). This is practically a trademark for PWK, he used it in all of his front-loaded designs. So that COULD be a PWK influence, it's hard to say. Since PWK was the earliest patent-holder and was there in the market place first with the most-est, he was certainly going to have an influence on horn designers of the time, I think that's going to be inarguable.

The Hartsfield also used a front-loaded approach so was that another PWK-instigated approach? Who knows...

It may not really mean anything - just a thought.

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Here's the 1945 Klipschorn patent drawing for a comparison. Note that the drawings are using a 12" field-coil woofer, not the 15" that we are used to today. But aside from being a little larger the modern Khorn still adheres to the layout in the drawings for the most part.

Khorn_pat_small.jpg

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I was thinking that that would have been a 15" driver, but now I'm thinking 12" or less. Also the dimensions are quite intriguing. There is enough room to produce a horn length of over 5 feet, and that could allow an Fc as low (maybe lower) as 40Hz quite nicely, due to the smaller size of the driver and therefore, the throat.

I didn't see any reference in the text as to the design Fc, so that remains a question.

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Here's my take on it, I hacked the catenoid model described in the previous reference to better describe my interpretation of the LEE design.

If in fact a true catenary expansion demands that the throat be the same relative size as the mouth, then the LEE is not a true catenoid horn, of course.

MOD_Catenoid.jpg

The question remains, why would somebody bother to patent a known "bad" design? That is not to say that there are no useless patents, but regardless, it costs quite a bit of money to do so...

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