Invidiosulus Posted July 2, 2008 Share Posted July 2, 2008 The fun and simple way. Drawing out the curve. Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted July 2, 2008 Author Share Posted July 2, 2008 Trace the curve onto some clearprint 1000HP. Set the traced curve on a piece of wood and tap through the paper with a small nail to transfer the curve to the wood via a sort of cartooning. Cut along curve. Repeat. Make a simple jig. Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted July 2, 2008 Author Share Posted July 2, 2008 Kerfing cut in the plywood allows flazability. Wood glue, not so much. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 2, 2008 Share Posted July 2, 2008 Very cool. Will you have any way of measuring your final results? Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted July 2, 2008 Author Share Posted July 2, 2008 Two sides of the horn. Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted July 2, 2008 Author Share Posted July 2, 2008 Very cool. Will you have any way of measuring your final results? Not on my own. But If I were to ship them to somebody... I'm probably going to run them in place of the K700 horn in the heresy's just for a first listen(that is, outside of the heresy cab as they won't fit inside). The plan is to build a pair to put on top of some Cornwall bass bins. I've been too lazy to try and figure out how low they should go. Length is a little over 10" Mouth area is about 89sq" For now just a proof of concept(sort of) really, just to see how hard or easy it is to make these things. Later iterations will probably use some pre kerfed stuff such as econoKORE. -Josh Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 2, 2008 Share Posted July 2, 2008 looks good to me...... Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted July 4, 2008 Share Posted July 4, 2008 very cool project. I'll be interested to hear your take when you get them in service. I used a pair of very similar horns built by a forum member in Khorns and was quite surprised at the openness of the sound. It was clearly an improvement over the K400 horn. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted July 4, 2008 Share Posted July 4, 2008 keep plenty of tequila and salt and pepper nearby? Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted July 4, 2008 Author Share Posted July 4, 2008 very cool project. I'll be interested to hear your take when you get them in service. I used a pair of very similar horns built by a forum member in Khorns and was quite surprised at the openness of the sound. It was clearly an improvement over the K400 horn. That's what I'm hoping for. I think this one is smaller then another well known K400 replacement, but I think it should work well with the Heresy or Cornwall. I can probably get Bruce to test them on his LS though as a comparo to the K400. keep plenty of tequila and salt and pepper nearby? Just a bottle of Ketel One actually. Oh, and maybe a couple of can's of Stroh's that my brother in law left in the fridge. Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 4, 2008 Share Posted July 4, 2008 Oh, and maybe a couple of can's of Stroh's... Oh yeah, the Stroh's... [+o(] Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted August 7, 2008 Author Share Posted August 7, 2008 When I cut the side pieces I hadn't noticed that the glue drying had pulled the curve a little tighter then it should have been which resulted in a curved cut once they were clamped back onto the jig and back to the correct tractrix shape A little work with a plane while they were on the conveyor belt and they took off. I mean they were flat enough on top and bottom to proceed. Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted August 7, 2008 Author Share Posted August 7, 2008 I missed some pic opportunities during the last part of construction so I'll do my best to describe in words. I think I would have used three pics for this part so I guess I owe everybody 3000 words. Anyways, I had the two side peices cut to size so I set them on the bottom piece and traced along both sides of the curved side pieces with a pencil, I also made a little check mark in the middle of each "block" on the kerfed side of the wood. Next I drove a small nail through the bottom piece centered between the pencil lines I had traced and aligned with the little check marks. I think I ended up using about 6 nails per side x top and bottom so about 20 nails total. Then since I had driven the nails through from what is about to become the inside of the horn I drove the back out and but them through the right way. Then I set the curved side pieces on top of the bottom piece with the nails sticking up through it and tapped it in place with the hammer. oh, I also had some wood putty on the edges of the curved side pieces so as to fill in any gaps left from the earlier error in cutting. I repeated the trace and hammer with the top peice and set it aside to let the putty dry overnight. The next day I sanded down the edges a little and took a flushcut saw to the throat mounting surface. I also mounted a little wedge on the bottom of the horn to provide me a T for the third screw of the threaded horn adapter to screw into. The wedge also acts as a foot for the rear of the horn. Here it is put together with a coat of primer. Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted August 7, 2008 Author Share Posted August 7, 2008 After the primer I shot it with some black spray can lacquer. I moved the crossover and the K55V and CT-125 out of the Heresy, connected the woofer to the input strip on the back of the cabinet(on the inside), ran the input strip to crossover wire from the woofer output from the crossover to the input on the back of the cabinet(on the outside), hooked my speaker wire to the crossover, etc... I placed a spare K55V and K77 in the Heresy cab to seal the holes from where I had taken the other stuff out. Once it was all put together my wifes first comment was "It looks really nice having the wires and crossover out where you can see them". Here it is with the new horn and such on top of the Heresy (lack of)bass bin. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted August 7, 2008 Share Posted August 7, 2008 Josh, Thanks for keeping us posted. I do have a couple of questions. Let me start with the dumb question first, since I am confused by how you obtained the Tractrix expansion. It looks like you traced a tractrix "contour" on each side. So I assume the tractrix "expansion" is now the sum of these two expanding contours? Am I understanding this correctly? However, these two expanding sides are then mated to a top and bottom which are each angled outward. So the top & bottom pieces themselves "contain" an expanding cross-sectional area (as a function of distance from the throat). Am I still correct on what was done? So I guess my question is how you made sure the total expansion (combined increasing cross-sectional area) was still a tractrix expansion? I have worded this in a clumsy fashion, but I think you can understand my confusion. Perhaps I do not understand what the "original" contour was that you traced out for the sides. Second question is how you constructed the throat. You are going from a circular cross-section at the driver to a (an approximately) rectangular cross section at the throat (beginning of the horn). Some folks have built a small coupler for this transition and tried to smooth out the "edges" with clay or something. What was your strategy, or was it not considered a problem (many don't bother with a smoothed transition)? Again, thanks for documenting this. -Tom Quote Link to comment Share on other sites More sharing options...
Invidiosulus Posted August 7, 2008 Author Share Posted August 7, 2008 Tom, For the horn shape I used the latest copy of the tractrix calculator spreadsheet on Erik Forker's website volvotreter.de The spreadsheet gives the dimensions for the curved and flat sides of the horn. So, I guess this provides the correct dimensions for a tractrix expansion. What is really correct could probably be debatable since even the klipsch tractrix horns use a slightly modified expansion(or so I heard) I don't have the equipment to test this sort of thing anyway so I figured I'd just build it and listen to it. The throat adapter is round and the throat is square. I didn't bother to try and smoothe the transition. It might make a difference but so far it sounds great. Erik Forker mentions at the bottom of this page, http://volvotreter.de/roundhorns.htm that smoothing the transition wasn't that great. Also keep in mind I am running them with the stock crossover points so I'm probably not taking too much advantage of the larger horn. But it doesn't sound WORSE then the K700 so I consider it a success. Some things I would like to try. More power tools! I think next time I would like to try cutting the curve shape into the top and bottom pieces with a band saw and then holding them at the correct angle while glueing and tacking in place some flexible side pieces. I think this would actually simplify the construction a bit. If I had a band saw. I feel this was good practice for building some horns for my cornwall things later this fall. Peace, Josh Quote Link to comment Share on other sites More sharing options...
Rob H Posted December 18, 2008 Share Posted December 18, 2008 I'm wanting to build a set of horns to fit in my klipschorn corner speakers not sure of how to get the specs. Any information would help. Thanks Rob Quote Link to comment Share on other sites More sharing options...
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