bigdnfay Posted January 28, 2005 Share Posted January 28, 2005 Hi all, I built a pair of k-horns a few years ago and so far been very happy with them. Now I think I'm ready to tackle the Jubilee. The Jubilee appears to be alot simplier to build. I have already draw up the cut sheets and am going to put together a two dimensional model to determine all the lengths and angles. After studing the AES paper from 2000, everything seems to be pretty straight forward. But, I do have a few questions. (1)Just before the second turn in the flare(see pic)it seems to get "choked off" alittle. The flare seems constant until it reaches that point. Is this part the design or was it a compromise? (2) I figure the mouth opening on the motorboard should be 2 3/8 by the inside diameter of the woofer. Is this correct? The image was taken from the AES paper and may not be to any kind of scale. So the first question may be for naught. So anyone with expertise in this area, info would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 One more question. Should the Jubilee be built in the k-horn tradition using 1/2 inch plywood for the interior parts and 3/4 inch ply for all the exterior parts? Or should 3/4 inch be used throughout? Quote Link to comment Share on other sites More sharing options...
Q-Man Posted January 28, 2005 Share Posted January 28, 2005 I got about as far as your drawing a few years ago. I drew it out to full scale on a piece of plywood. My drawing was for a 15" woofer. I drew mine before we heard about the Jubilee, and how it uses two 12" woofers. As you can see from your drawing, it's simply a LaScala facing rearward with a longer and more gradual flare rate so it will go lower. I may get back to this one of these days, but I'll go with two 15" woofers instead of the 12s. I know my reply didn't answer your question. I just thought that I would let you know that I share your interest. You may make me go dust off that piece of plywood and start calculating the flare rate again. The first one to go collects $200.00. Quote Link to comment Share on other sites More sharing options...
Q-Man Posted January 28, 2005 Share Posted January 28, 2005 I would use 3/4". It's more ridged and easier to work with. Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 Thanks Q-man I just wanted to be sure about the plywood. It will make a difference in getting lengths and angles correct. Big D Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 This is what I came up with. Makes things more difficult but it keeps the flare more constant. Big D Sorry about the pic Quote Link to comment Share on other sites More sharing options...
3dzapper Posted January 28, 2005 Share Posted January 28, 2005 On the expansion rate, if your arrow is named the "x" axis and a line perpendicular is the "y" axis, there is a large expansion of the y axis at the same point and would be would be the sufficient. This was most likely a compromise to enable the large flare expansion on the outside to be unimpeded. The rounded end where your arrow is looks like an ink blob, I wouldn't build that in. Rick Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 3D, looking at the second pic (jubilee ,would this allow a better transition to the third leg of the flare? Big D Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 28, 2005 Share Posted January 28, 2005 The expansion rate changes between the two sections at the rear fold, so that could explain the difference. But I suspect that it is probably a scaling problem with the diagram. I made up a drawing of an alternative approach, but I can't get it to upload, so can't help... DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 28, 2005 Share Posted January 28, 2005 Well, silly me - I don't know if this will help in any way, but here it is... DM Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 D-man, I thought of that to. Did some drawings on graph paper and it showed the opposite effect. the area before the turn is larger(3 3/4) than the 3 inches determined in the AES paper at point C. Big D Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 28, 2005 Share Posted January 28, 2005 My take on this is that the inner channel wall panels are slightly too "long" in the diagram. That is, they extend too far towards the back reflector. Probably a scaling issue with the drawing. Another thing I think is that it would not really be in PWK's interest to publish true scale drawings, so people could do exactly what you're doing, in effect. I would take their accuracy with a grain of salt. If it was me, I would want them to be "close enough" for publication, but not to build from. However, you are the first that I know of to attempt this, so please, by all means, keep us informed. DM Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 One other issue. I have heard mention of passive radiators used in the "home version". From the design in the AES paper, There are only 2 places I could imagine them. (1) Placed in between the 2 woofer chambers, but it seems to me the effect would be cancelled as the woofers work in tandom. (2)In the woofer doors. Any place else would cause a radical change in design. Please correct me if I'm wrong. Big D Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 28, 2005 Share Posted January 28, 2005 Only my opinion, but it seems to be that one of the two 12" woofers would be the passive radiator. It would feed its horn throat just like a "live" driver. This would somewhat lessen the overall bass output and allow for a broader selection of possible midrange drivers and tweeters for home use due to the reduced bass output. I would not think that this arrangement would be optimum in any sense as it would be pulling on the throat as the live driver was pushing, etc. Otherwise, there is no way that the bass horn would work as the different wave polarities would tend to cancel each other, the stronger "live" driver winning out in the end. I've seen a patent on a reflex ported double horn kind of thing that is somewhat related to this subject. DM Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 2 "live" drivers it is. No passive. Big D Quote Link to comment Share on other sites More sharing options...
Marvel Posted January 28, 2005 Share Posted January 28, 2005 Looks like a lot of pieces don't you think? If you make the back of the channels too rounded, you will lose high end off the woofers. Marvel Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 Thanks Marvel, It appears I should build as is with no changes. Leave well enough alone. Big D Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 28, 2005 Share Posted January 28, 2005 That would be what I'd do, too. If you've calculated the cross-areas and they are correct, then go for it, dude. Have you worked out the double throats? I figure that they are like smaller versions (one-on-top-of-the-other) of the LS throat. DM Quote Link to comment Share on other sites More sharing options...
bigdnfay Posted January 28, 2005 Author Share Posted January 28, 2005 They are stacked and use seperate flares until they get to point C. then they combine to point D. Big D Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 28, 2005 Share Posted January 28, 2005 Yes, how WIDE is the throat, i.e., depth of the channel? It's somewhere around 2", I would think. DM Quote Link to comment Share on other sites More sharing options...
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