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Tractrix horn calculator for Belle clone mid


avguytx

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Just to add a little to the above... I already have a new pair of K-33's and this goes back to my Belle clone build. They will be going in the living room for now so the clones will be built to about the same size as original; the top hat having a little room to give for mid horn size. One day when I have the attic finished out, or a different house, I can go larger horn without worry of aesthetics. I'll be using either the Selenium D-250x to start or K-55's and CT-120's or D220ti's for the HF.

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The calculator shows you have to edit 4 different areas for designing a horn by throat size.  I'm assuming (could be bad) that using a K-55-X or Selenium D-250X is a 1" throat size.  For flare frequency, should I work with 350HZ?  I've read that the frequency needs to be lower than the crossover point?  Also, it shows the ratio of width to height and, if you leave it at 1.5, it makes the horn taller than it is wide and I'd rather have it wider than tall.  Does the ratio need to be changed to, say, .60?  If I do that, I end up with what seems to be a happy average size of 14-5/16"" wide x 8-11/32" height x 12-5/8* depth.

 

I can build it but I really need help with this part!  My best friend owns a company locally that does CAD design for steel structures, etc., and has AutoCAD where these figures can be entered in.

 

Oh, I got the price on cost for a new pair of K-55-X's.  They'll be about 4x the price at landed cost.  Hmmm.... 

Edited by avguytx
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Just sent a message back to you...

 

You have to rotate the calcs 90 degrees. Erik's horns have the sides as flat pieces and the top/bottom pieces curved. Only metric, but you can enter the three columns that are generated as files in Autocad, and it will draw the curves for you. Much easier that drawing out a bunch of points and drawing manually.

 

A 1" throat would be 25.4mm.

 

If you are looking to have a 400Hz crossover, 350Hz for the fc would work. Lower would be better, but your horn will probably get bigger than you want.

 

Bruce

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Thanks again, Bruce.  Isn't the high pass cutoff on a Belle 500hz? Or is it 600?  I can adjust that accordingly.

 

I'll probably stay with the 350hz fc for the moment so they'll fit in the top section but later, I'll go to a 200hz horn when they can go on top in the open.  Then, I can time align them with a tweeter on top.

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Also saw this line and wondered if it's a misspelling or I'm missing, yet, something else...

Throat dimension (with = heigh)

If, let's say, the throat dimension is 3/4" (1.905 cm), there's an equation in that box. Does the 1.905 go there or does art of it get entered into that equation?

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  • 3 weeks later...

Anything that can run Autocad scripts should work. The spreadsheet generates three columns  of the numbers that you should be able to save out with a *.scr and run.

 

I don't have autocad, and I'm not sure what my son used when he made some.

 

Bruce

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Is your goal an exact replica?  Why hold to the K55?

 

I believe Roy Delgado is a genius and if your going to take the time to build something, you should consider the 2-way K510 design.  One day you might could score a TAD-4002 and it just screws right on there and I think the larger throat sounds a lot better, less compressed.

 

I like the K55, but the K69 is way better and the Beryllium TAD is way way way way better IMHO.  I suggest a horn that can use one of these, and I bet you could find a set of the K69 for pretty cheap.  I'd bet you a milkshake that if you built both top hats, you'd never listen to the K55 after hearing the other.

 

I'd love to hear a 2-way Belle w/ TAD vs. a Jube w/ TAD combo I bet they are really close.

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Unfortunately that would be way out of my price range as good as it would be.

K-510 horns (the smaller version of the big K-402 modified tractrix) do sound good. 

 

If it is of any help, I do have a single, used K-510 horn and a JBL 2445 driver. This is a good combination. The JBL will sound better than the K-69 driver and there are plenty of them on eBay. 

 

Consider trying this as an experiment. If it works, then you would need to find a second K-510 horn (they do come up occasionally).

 

If you are serious, PM me and we can figure out a price.

 

-Tom 

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I do appreciate the offer but, for now, I'm trying to keep everything under the top hat.  Now, when we buy/build a new house and I have them in a separate room, then I'll open up for more options.  I know I could build the top section a little taller and get the K-510 in there, though.  Hmmm...

 

I have the wood, and capability, of building the wooden Tractrix horn...it's just getting it plotted out.  I got the information saved from the spreadsheet columns to a text file and emailed to my buddy to change the extension to a .scr file.  Oddly enough, Gmail blocks those file extensions.  

Edited by avguytx
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