Cross Section Of a K-Horn

[BerndH]

Hallo,

i uploaded a picture of this transparent klipschorn, which HDBRbuilder told in his first message.

The patents describing a corner horn are shown in a klipsch broschure from 1957. Mr. Sandeman patented the first corner horn, a trihedral horn, and PWK referred to this in his first paper to corner horns. In 1940 PWK patented his prototype of the bass section an in 1945 PWK patented the high frequency section.

Maybe this helps in this discussion.

[BerndH]

Sorry, in my first reply the upload of the transparent klipschorn failed.

[kenratboy]

Very nice!

I still need to see one!

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Receiver: Sony STR-DE675

CD player: Sony CDP-CX300

Turntable: Technics SL-J3 with Audio-Technica TR485U

Speakers: JBL HLS-610

Subwoofer: JBL 4648A-8

Sub amp: Parts Express 180 watt

Center/surrounds: Teac 3-way bookshelfs

Yes, it sucks, but better to come. KLIPSCH soon! My computer is better than my stereo!

For JBL related subjects and more fun, click: http://www.audioheritage.org

[HDBRbuilder]

Kenratboy, et. al.:

If you look at that clear plexiglass k-horn, you can see that the woofer fires forward in it...through a horizontal slot.

Then you can see a horizontally mounted strip ahead of the woofer...this strip has a isosceles triangular-shaped cross-section to it with the "top" of the triangle facing the woofer...this is the "splitter"...where the soundpath from the woofer "splits" into two separate pathways, one going upwards and one going downwards. This splitting of the horn into two separate horns at this point is called a "bifurcated pathway."

These two pathways are carried toward the top and bottom of the bass cabinet in those trapezoidal shapes above and below that "splitter piece. The upper trapezoid widens as it goes upward to achieve its "horn-flare rate", while the lower trapezoid widens as it goes downwards to achieve its "horn-flare rate." All of this can be easliy seen in the photo of the plexiglass k-horn.

Now, for the sake of ease of explanation, let's just take the upper pathway from this point, with a full understanding that the lower pathway mirrors the upper pathway in its function as a horn lens.

We have established that the first portion of the horn widens from side to side to achieve its "flare rate" as the soundpath goes upwards. Once the soundpath reaches the top of the bass cabinet, it is bent again so that it flows to the rear of the cabinet. Here is how the "horn-flare rate" is achieved after this bend:

The soundpath, which is now firing towards the rear, is limited at this point by the top of the cabinet, and cannot expand upwards to achieve its "flare rate". It also cannot achieve its "flare rate" by expanding to either side as it follows its pathway towards the corner, SO, it has only one option to achieve this, and that is to have its bottom side of its pathway provide the "flare rate"...and that is what happens...the bottom of the horn flares downward along the outer side of what is called the "pyramid" section of the cabinet.

Now the same thing is happening at the bottom of the bass cabinet to the lower split of the soundpath, but in a mirror image of what is happening to the upper one.

As these two separate soundpaths fire towards the rear, they meet at the point where the tip of the "pyramid section" is...and they become ONE soundpath again and, in essence, One horn lens mouth...but ONLY for a moment and for a SHORT distance!!

Now they are together and firing toward the rear... right into the corner, but the soundpath doesn't make it quite to the corner!! Instead, this now-rejoined soundpath hits the "tailpiece" of the bass cabinet and is again reflected, but THIS TIME it is reflected to each side by the tail piece. It's pathway is again "split" and it has no choice at this reflecting point but to follow the walls on each side of the tailpiece and turn forward to run along the outside of the rear of the bass cabinet, along either side of it...with one half of the soundpath going to the left and one-half going to the right as it is trapped by the floor surface and the top panel to the bass cabinet.

There is yet another "horn-flare rate" achieved as the two soundpaths flow forward along the walls...toward the listener. This "flare rate" is achieved by the difference between the angle of the room corner(90 degrees) and the difference of the "included angle" of the back of the bass cabinet(less than 90 degrees)...IN OTHER WORDS, the flare is actually INWARDS ..TOWARDS each side of the back of the cabinet as the soundpath flows forward along the walls on either side of the cabinet...thereby achieving the final sections of the "flare rate" of the bass horn...as the soundpath travels forward towards the listener.

GEEZ!! I hope this explanation helps some of the members somewhat!! It is MUCH easier to explain it in person with a room corner, a megaphone, and a chunk of scrapwood!!!

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[tpg]

That picture helped me about 100%. It is nice and clear now. lol It looks far simpler to build now... though I will take everyone's suggestions about them being no easy thing to build. Maybe someday if I ever have any loose cash (or if I ever get my speakers/money from the eBay guy...) I will look into building one for fun. Right now i am going smaller though. I am thinking about turning my old Altec Lansing speakers with the blown amp into some fully hornloaded things. But I don't have the cash.

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SoundWise / ProMedia Tech Support / 1-888-554-5665s>

[WMcD]

A couple of comments. I've said most of this before.

You should realize that regardless of the twists and turns, a common exponential horn doubles in cross sectional area every "x" distance from the small end at the driver (throat) to the big end open to the room (the mouth).

There is an issue in making the turns. They should be made where the cross sectional area is small, so that the radius of the turn is small. More specifically, the outside of the turn is not too much longer than the inside. Things could get delayed or out of phase because of the difference. This is more critical at high frequencies where the the wavelengths are small and out of phase conditions develop.

That is the theory anyway. But treble loss may come from other factors which the dual path doesn't solve.

How to do this? One way is to have two paths. You have to think about it for a while. Essentially, if there are two paths, the cross sectional area at a turn is half as big as if there are two. That seems to be why production Klipsch bass horns typically use two paths, which may join at one point as at the tail board.

If you want to learn more about bass horn design generally, let me suggest you get U.S. Patent 4,138,594 to Klipsch off the U.S.P.T.O. site. www.uspto.gov. Follow instructions to get the TIFF plug in viewer so you get the image of the patent.

The patent is about a bass horn with a single path. However it is very good tutorial about throat size, mouth size, and simplicity in bass horn design. All by PWK. It is more understandable than a textbook.

Gil

[jnorv]

I suspect that the big problem in folded, base horns are the reflections at the turns that are propagated back toward the throat. There is a curve in Beraneks Acoustics book for losses in constant area ducts with 90 degree bends. The losses were a function of the wavelength and the width of the duct. This data was from HVAC ducting where the noise attenuation is a good thing. But the same phenomena holds in folded horns.

Jim Norvell

[kenratboy]

I just about got it!!!

How in the .... do you think that up? Science aside, thats some complex stuff, and for it to work so well!

Thanks!

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Receiver: Sony STR-DE675

CD player: Sony CDP-CX300

Turntable: Technics SL-J3 with Audio-Technica TR485U

Speakers: JBL HLS-610

Subwoofer: JBL 4648A-8

Sub amp: Parts Express 180 watt

Center/surrounds: Teac 3-way bookshelfs

Yes, it sucks, but better to come. KLIPSCH soon! My computer is better than my stereo!

For JBL related subjects and more fun, click: http://www.audioheritage.org

[John Warren]

Jim- that is the problem with folded bass horns. they reflect back to the throat. the models miss this

and deviations occur. US Patent 2,866,513 is an early

attempt to deal with reflections. White arrived at this concept by comparing the sound of a straight bass horn to that of a folded Olsen type enclosure.

if you go to the USPTO website to examine this patent, it is interleaved with another patent and missing the proper figures associated with it. a work request to rescan the original has been issued. It will be a few weeks before it is fixed but, from past experiences, they fix them.

A speaker line in the 50s was based on this patent (Stan White, Inc).

This message has been edited by John Warren on 08-07-2002 at 05:47 AM