Bob,
Post 188 and 191 in the cornu thread.
http://www.diyaudio.com/forums/full...uilding-cornu-spiral-horn-now-you-can-20.html
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Cardboard box
Cut up a box, taped it tight, dropped in some 3 inch FR drivers hooked it up and it sounds good.
For a free box.
I was thinking about trying out a Cornu spiral out of card board and dropping in these drivers.
Is a 24" or smaller size a safe way to go with these 3" drivers? They aren't too deep maybe 2.5".
An externally hosted image should be here but it was not working when we last tested it.
Cut up a box, taped it tight, dropped in some 3 inch FR drivers hooked it up and it sounds good.
For a free box.
I was thinking about trying out a Cornu spiral out of card board and dropping in these drivers.
Is a 24" or smaller size a safe way to go with these 3" drivers? They aren't too deep maybe 2.5".
I thought about cardboard also. But if you find the right "Dollar Store" the $5 investment in foam board for two 24s provides a very stable and strong build.
I second what Bob says.🙂
I used to build with cardboard but find that it is not as stable as it bends in one direction easier than another and the color is just plain objectionable. Having said that, I would not discourage trying it out in cardboard as for the spirals, cardboard nicely bends in one axis and is stiff in other without requiring the scoring with a razor. You can use double layer cardboard for the faces which is stable and strong in both dimensions. In a pinch, you can glue two sheets of single ply cardboard with grain crossed at 90 deg. Let dry and use for face. You will have to cover the cardboard with vinyl contact paper, paint, cloth, etc as the kraft brown color is fugly. Notice how most speaker cone paper is black? They add carbon black to it otherwise it would have the color of brown cardboard and people would ask why they are paying so much money for a cardboard driver 🙂.
Really though, if you can locate a Dollar Tree with the 20x30 in foam core boards, buy a dozen or so and you will have lots of speaker building adventures ahead of you.
Those drivers look perfect for trying on this project. What model and size are they?
Good luck!
I am out of foam core... the hands are getting restless again not having built something with a razor and hot melt for 2 weeks now. Another run to Dollartree is in order, I might have to buy a whole case of 25 sheets this time like Cal does 🙂 SWMBO actually said she will pick it up for me if she happens to go by the store! 😀
I have been day dreaming about building a 50 driver line array using a foam core open baffle cabinet with the $1 Aurasound 3 in neodymium full range drivers from Madisound. The drivers are $1 if you buy 50...
I have been day dreaming about building a 50 driver line array using a foam core open baffle cabinet with the $1 Aurasound 3 in neodymium full range drivers from Madisound. The drivers are $1 if you buy 50...
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I love your SWMBO. Please mention my name the next time you give her a big hug.
The cases up here are 50 sheets. They are so heavy I can only carry half a box at a time. 😀
The cases up here are 50 sheets. They are so heavy I can only carry half a box at a time. 😀
Actually I have 24 ft ceiling in family room, but I meant 25 per side for 7 footers. They are 16 ohm though, I am not sure how to wire to get 4 or 8 ohm total unless 16 drivers per side.
18 drivers: 3 sets in series of 6 in parallel = 8 ohms
20 drivers: 4 sets in series of 5 in parallel = 12.8 ohms
21 drivers: 3 sets in series of 7 in parallel = 6.9 ohms
24 drivers: 3 sets in series of 8 in parallel = 6 ohms
24 drivers: 4 sets in series of 6 in parallel = 10.7 ohms
25 drivers: 5 sets in series of 5 in parallel = 16 ohms
dave
20 drivers: 4 sets in series of 5 in parallel = 12.8 ohms
21 drivers: 3 sets in series of 7 in parallel = 6.9 ohms
24 drivers: 3 sets in series of 8 in parallel = 6 ohms
24 drivers: 4 sets in series of 6 in parallel = 10.7 ohms
25 drivers: 5 sets in series of 5 in parallel = 16 ohms
dave
Planet10,
Thanks for the impedance calcs. I think the 6 ohms with the 3x8 is probably a good compromise. I wonder if the DTA100 can handle 6 ohms?
Thanks for the impedance calcs. I think the 6 ohms with the 3x8 is probably a good compromise. I wonder if the DTA100 can handle 6 ohms?
If you want some fun with the Cornu, download Bruce Cockburn 'If I had a Rocket Launcher' or Jimmy Buffett 'Pascagoula Run' and turn it up. 🙂
I don't understand the 45 deg? Are you referring to line array? Melo Theory made a 45 deg flooder line array but no stagger.
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Yes,
The [somewhat] pincushion frame allows you to turn them 45º to align them closer if you choose two rows.
The [somewhat] pincushion frame allows you to turn them 45º to align them closer if you choose two rows.
Ok, that's 48 drivers per channel then, 96 total. I am getting carpel tunnel syndrome just thinking of all the crimping of the connectors! That can get real loud I bet. Have you ever made line arrays? Why do I bother asking a speakerholic, of course you must have! 🙂 I will have to get that Jimmy Buffet song...
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Is there a benefit to using foam core for an OB?
What about a BLH line array?
You could arrange it to be a front and back horn. Push-Pull.
The only benefit is that there is no sawdust and it is light and portable. I was thinking OB because of the extremely high qts of these units. Tell me more about push pull BLH.
Happy new year everyone!
Happy new year everyone!
Ok, I just looked at the parameters. Yup, OB. 🙂
You could do a push-pull, it would take a bit of eq. But it would be a great experiment, especially with such an easy construction method.
I would have to draw something on the vector program to give an example. I could do that tomorrow.
You will need eq for an OB anyhow, or any type because that driver doesn't have a rising response.
You could do a push-pull, it would take a bit of eq. But it would be a great experiment, especially with such an easy construction method.
I would have to draw something on the vector program to give an example. I could do that tomorrow.
You will need eq for an OB anyhow, or any type because that driver doesn't have a rising response.