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Old 13th December 2012, 09:44 PM   #701
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I used more than a bag of glue sticks so that was $7 alone.

I think I need a drink
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Old 13th December 2012, 09:46 PM   #702
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mine only cost me $21.50 for the two foamcore boards

coz i already had the glue, already had the stuffing, already had the drivers, and wire. plus the amp, $3.50 and about 4-8hours on it as well.

would have been much cheaper had i found a cheaper foamcore panel.
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Old 13th December 2012, 09:48 PM   #703
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Ya all I had to buy was the foam, facers, glue and trim. The trim was the most expensive at $65.

That is now speaker set #33 that is ready to, or very close to, plug and play. When does this end?
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Old 13th December 2012, 09:49 PM   #704
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One of the problems with scaling these spiral horns is that, for optimal performance with a given driver, you need to do more than just scale all the dimensions. The good news is that it is easy to design your own custom spiral horn.

1. Use Hornresp to design a back-loaded horn using your driver of choice. You can use whichever horn profile that gives you the response you want - parabolic, conical, exponential, even multi-segment.

2. Work out how deep the horn will need to be. It has to be:
- deep enough to mount the driver
- The right depth to provide the correct rear chamber volume.
- shallow enough so that the throat opening of the horn path(s) is not too narrow - a tiny slit won't work well.

3. You can estimate how big the enclosure will be at this time. Hornresp will tell you the volume of the horn. This will (approximately) be the volume of the final enclosure. Divide by the depth, the result will be the area of the front/rear panels. For a square enclosure, the square root of this area will be the side dimensions. If you don't like the answer, back to the drawing board...

4. Export the horn dimensions. By default, it will export a horn that flares in both width and height. In the export menu, go down either the height or width column and set all the values to your desired depth value. The values in the other column will automatically adjust.

5. Decide how many horn paths you want (one, two, 3, 4 etc).

6. On a large piece of paper, draw a circle corresponding to the diameter of the central chamber.

7. Draw mark(s) on the circle at the point(s) where the horn spiral(s) will start. If more than one, space them evenly around the circle.

8. If you are doing a multi-path horn, divide the dimensions from step 3 by the number of paths. (If a segment point is 5 cm wide, and you are doing a 4 path horn, each path will have a width of 1.25 cm at that point.)

9. Using the width versus length dimensions, start drawing the spiral(s). You'll need to adjust the angle of the inner wall of the first part of the spiral(s) so that they become the outer wall(s) of the next spiral(s). This will make the central chamber slightly larger in area, so you may need to move your inner starting marks in slightly to average out the difference.

10. Continue drawing the spirals, plotting the dimensions every couple of centimetres of length. You can "join the dots" with straight lines if you keep the length increments short, but you'll find it easy to "freehand" draw nice curves. If you're doing a multi-path horn, "sync up" the dimensions every 90 degrees or so in case of accumulated measuring errors. Remember to allow for wall thickness, especially in the inner (narrow) parts of the spiral.

11. When you get to the mouth(s), draw an enclosure shape around the whole thing (for example, a square box around a 4-path horn) and blend the final curve so it fits a side of the enclosure.
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Old 13th December 2012, 10:02 PM   #705
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Gentlemen, I think it's time to start a new thread about this. I think many persons may be interested but won't look into this thread simply because of the title. I will do the honours with a link to this thread for all the info it contains.

Cheers.
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Old 13th December 2012, 10:02 PM   #706
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Don,
Thanks for the design sequence! We can all run off and see what we come up with using our Favorite driver. One thing we have notice is that the driver choice and exact spiral dimensions are not so big a deal. The cornucopya is very forgiving. I just figured out how to model an arbitrary spiral in Solidworks... But I still think hand drawing is best way to get going on new designs.

Last edited by xrk971; 13th December 2012 at 10:14 PM.
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Old 13th December 2012, 10:04 PM   #707
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by Cal Weldon View Post
Gentlemen, I think it's time to start a new thread about this. I think many persons may be interested but won't look into this thread simply because of the title. I will do the honours with a link to this thread for all the info it contains.

Cheers.
What will you name the thread? I think we can start it off with a summary howto and cool photos.
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Old 13th December 2012, 10:07 PM   #708
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You can tell me what you think when I have done it. I am open to suggestions and can change it at any time.
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Old 13th December 2012, 10:15 PM   #709
xrk971 is offline xrk971  United States
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How about 'Beautiful, cheap, and easy'

Ok, ok, ok....

Cornucopya: Beautiful, cheap, fast, and easy.
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Old 13th December 2012, 10:21 PM   #710
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Ever think of building a Cornu Spiral horn? Now you can!
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