False corners screwed into K horns?

[edwinr]

I think that's the rudder you're referring to.

[3dzapper]

Dean,

It's 12 1/2" on my "C" models from the back of the grill to the front of the front face.

Rick

[Deang]

Thanks Rick!

[iwillwalk]

dean,

are you doing this to a pair?

[iwillwalk]

dean,

are you doing this to a pair?

[Deang]

.

[HDBRbuilder]

Dean,

The TSCM was an industrial K-horn with sides attached. It had TWO braces betwen the attached sides and the bass bins, in order to eliminate vibrations to the 3/4" plywood sides.

Jim Cornell has one of these and has posted pics of it numerous times. Just look at the pics to determine how the side braces are installed. My suggestion would be to install the braces with screws and glue to the inside of the attached side panels, while using glue blocks and screws to attach the braces to the bass bin itself.

Remember, in order to keep from REDUCING the final flare of the bass horn, the sides need to be installed to the outer EDGES of the upper panel, NOT to the bottom of it. You will also need to install a panel like that atop the bass bin to the bottom of the bass bin to accomplish this. With the inclusion of the two braces on either side, you should be set.

[iwillwalk]

dean

please post step by step info & pics if any way possable, because i'm going to do this next. but need some good info to the same.

thanks

steve

[Trey Cannon]

I am not sure why, but the khorns that I have tested with 3/4 plywood screwed to the back rolled off prety hard at 100 Hz.

I can not say if it was due to the thickness of the wood or what, but they did roll off.

Edit: Now that I think about it, the unit I tested had the "corner" come out even with the edge of the khorn.

PWK suggested that the corner be 4 ft to each side.

With the corner being the "mouth" of the horn, making it smaller / shorter would change the low freqency cutoff.

[Deang]

.

[edwinr]

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On 7/20/2004 1:18:49 PM Trey Cannon wrote:

I am not sure why, but the khorns that I have tested with 3/4 plywood screwed to the back rolled off prety hard at 100 Hz.

I can not say if it was due to the thickness of the wood or what, but they did roll off.

Edit: Now that I think about it, the unit I tested had the "corner" come out even with the edge of the khorn.

PWK suggested that the corner be 4 ft to each side.

With the corner being the "mouth" of the horn, making it smaller / shorter would change the low freqency cutoff.

----------------

That makes a lot of sense. The stuff I've been reading about horns and corner loading suggests you need a proper corner whether false or not, i.e. the side walls would have to extend well out from the Klipschorn. Because the corner does in fact form part of the horn mouth. That's why the Klipschorns work so well from such an apparently small folded bass horn design. The folded bass horn is in fact not small at all - because the room corners are really part of PWK's original design. He supplies the mid and treble horn package and part of the folded horn component - we supply the rest.

(appologies to those in the forum who already know this!)

[Ki Choi]

Try the link below for additional information from my previous post on the same subject:

http://forums.klipsch.com/idealbb/view.asp?topicID=47395&forumID=66&catID=19&search=1&searchstring=&sessionID={C0F6F245-1D19-47C2-949B-6E4B210F2225}

Ki

[edster00]

You will have to type the closing } in the url above to get the page to load. For some reason the BB always leaves the closing } off.

Or you can click here to go to that thread.

[Deang]

.

[Audio Flynn]

I am not a disciplined as you.

And i used to build PA cabinets.

The Parts Express Pebbel finnish would be fine for me.

[Deang]

Well, it does look nice -- and would be a hell of a lot less trouble.

[richinlr]

Regarding the roll-off at 100 hz. with false corners...

After studying horn design theory, maybe I can shed a little light on this.

The genius in the K-horn comes from using the walls to continue the flare. This makes the APPARENT mouth well outside and far away from the enclosure itself.

One of the things that makes a horn both efficient and good sounding is the acoustic impedance match with the air. A horn is basically an acoustic transformer. It works this way:

1. At the throat, the sound wave is high amplitude and high pressure.

2. As the wave travels down the flare the amplitude stays high but the pressure falls (because the volume it is travelling in is getting larger)

3. In a perfect world, by the time the wave reaches the mouth the pressure has fallen to the point that it is a very good match with the air.

There are two critical components of horn design that affect its low frequency response. One is the area of the mouth and the other is the amount of flare at the mouth. Take a good look at the midrange and tweeters and notice the flare is approaching flat at the mouth. The tweeter and midrange are relatively easy to make this way because they don't need a very large mouth. On the other hand, a 32 Hz wave needs a VERY large mouth (someone correct me on this but I think is would need to be 16 feet square.). I think PWK also said one time that since the wave length at 32 Hz. is 16 feet, you need a room that has at least one of its dimensions to be 16 feet in order to fit the wave in the room.

So... back to false corners.

Unless the false corner is extended to some point BEYOND the enclosure, the low frequency cut-off is going to increase quite a bit (100 Hz is not unreasonable) due to the resulting effective mouth size and tight flare at that point (sound wave is still relatively high in pressure due to the lack of flare).

Hope I haven't totally bored everyoneand I hope this sheds some light on the issue of false corners.

By the way, were I to make false corners, I would use 2 x 4's as a frame with 3/4 inch plywood HEAVILY braced and maybe even spray the surface of the plywood with automobile undercoating just to control the high pressure at these points.

One other thing - Ask PWK what is the best enclosure material and he would reply 'concrete'...

[Deang]

Thanks for the post. I appreciate explanations I can understand.

Based on some reading in another thread, it appears the 100Hz roll-off was measured on Steve Philips' Klipschorns using only 2 foot side panels.

I can't believe the lack of suggestions here on my problem. What a bunch of wieners.

[sunnysal]

dean unless your walls are some dark color I would suggest painting the false corners white. I have seen photos and the white ones always seem to semi dissappear or at least look less intrusive in white. also, by painting white to start, you can always paint over it (treat it as a base coat) if you change your mind later. tony

[Deang]

Thank you Tony, that's an excellent suggestion.