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DIY K-horn Pics

John Warren

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John--Animal glue is made from animal remains (bone, marrow, cartilige, hoof and hide). It's been in use for 500+ years. I use it because it has 5 main advantages over synthetics-it's slow to set (a must making a K-horn), it's a gap filling glue, it forms a true chemical bond to the cellulose fiber in wood, you can modify the viscosity by heat/cool and it's expansivity is similar to wood which is why 300+ year old furniture and musical instruments hold together to this day. It's drawbacks are that it has no resistance to water, it has a short shelf life (3-6 months), it's set time is sensitive to humidity and it's expensive. Also, when wet it's acidic so fasteners should be made from stainless steel. The moisture resistance is improved by shellac or poly. Tite-bond sells animal glue called "Liquid Hide Glue". It's in a brown bottle that has a date stamp on it, use within 6 months. I've used it and it works great. For this project, I used a flaked form of glue (add water), a glue pot and a set of brushes.

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In view MVC-026X.JPG, what is the purpose of the triangular-shaped cut-outs near the edges of the board that contain the slot? I've never seen that before. Looking at the photo again, perhaps it adds stiffening to the side walls without reducing the back-chamber volume?

I used 10 coats of marine-grade clear polyurethane in the slot region on my pair. It left a finish as smooth as glass on the phase plug board. I was hoping it would improve bass impact but all it did was improve the upper bass frequency response.


John Packard

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John P-

The triangular holes on the side opposite the woofer access are needed to gain access to the volume of air located in the ramps. Look at -004X. The volume in the ramp is accessed by the triangular cut-outs on the baffle. In this design the volume of air behind the woofer includes the volume of air in the top and bottom ramps. That is the reason for the little 30° notch shown next to the screw in -004X. It's a vent.

The cut-outs on the woofer access side of the baffle do nothing since I did not make the rails symmetrical. Direct access to the volume in the ramps is possible.

The plans call out for two V-notched rails but it is obvious that the woofer access port would be blocked. For symmetry I just V-notched both sides of the baffle.

As you can see, the baffle board in this pr. is somewhat different than the present Klipsch design. The 3/4" thick plywood plate resting atop the baffle initially was to be removable but getting a good seal (wood flex) is difficult. Since throat construction is the most critical part of the design, it must be rigid so I went the other way. I installed 8 c'sunk T-nuts into it, painted the entire side with glue and then bolted/clamped it to the baffle board. It result was a rigid, 1 1/4" thick baffle. The face of the plate that the woofer bolts up against gets one coat of poly as did the throat, more for dust control than anything else. To get further stiffening the woofer is then bolted down with 8 machine screws. This is why I'd like to see a cast frame woofer, better stiffening.

I am currently constructing two pairs using 1/2" and 3/4" marine grade 14-ply Birch plywood. Each will have 1 1/2" thick baffles and 3/4" thick boards that make up the V behind the woofer. These panels should not be made out of 1/2" per the current factory practice, they resonant like crazy.

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Tony, What you think is the "wedge" in the pic is actually a mid strip that runs down the middle of the throat. It "bifrucates" the throat. The wedges (there are actually two) are at either side and run parallel to the long axis of the slot as you mentioned.

Scroll to the bottom right of -008, you should get a glimpse of what the throat looks like.

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