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Ever think of building a Cornu Spiral horn? Now you can!
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Old 9th February 2018, 09:12 PM   #2441
planet10 is offline planet10  Canada
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Ever think of building a Cornu Spiral horn? Now you can!
The German patent applies to Germany, and possibly all of th eEU, i don’t know how applicable it is in North America. Anyone know th elegal status of that?

dave
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Old 9th February 2018, 11:31 PM   #2442
xrk971 is offline xrk971  United States
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Ever think of building a Cornu Spiral horn? Now you can!
If they applied for the Patent Cooperation Treaty (PCT) filing then it applies in all countries that they checked applicable. Probably includes USA.
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Old 11th February 2018, 03:04 AM   #2443
Cal Weldon is offline Cal Weldon  Canada
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Ever think of building a Cornu Spiral horn? Now you can!
One down. These 48"ers take a bit of time when there's 46 ft. of foam in each.
Bad angle photo. They're actually true to the stencil.
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Old 11th February 2018, 03:57 AM   #2444
scott68 is offline scott68  United States
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Off on a tangent thinking - what would be the result if we turned a Cornu spiral on its head and reversed the horn into a tapered Transmission line. Use .50 Qts or higher speaker, make the center 2 to 4 times speaker's SD and maybe with the two different length channels, one of the channels will offset the 1st harmonic? Probably not a good idea since I haven't seen this mentioned anywhere.
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Old 11th February 2018, 03:29 PM   #2445
xrk971 is offline xrk971  United States
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Ever think of building a Cornu Spiral horn? Now you can!
Quote:
Originally Posted by scott68 View Post
Off on a tangent thinking - what would be the result if we turned a Cornu spiral on its head and reversed the horn into a tapered Transmission line. Use .50 Qts or higher speaker, make the center 2 to 4 times speaker's SD and maybe with the two different length channels, one of the channels will offset the 1st harmonic? Probably not a good idea since I haven't seen this mentioned anywhere.
This was covered as one of the alternate embodiments in the Cornu patent and also shown in their website. It would work to give tight bass but less gain. I havenít modeled it yet.
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Old 11th February 2018, 06:52 PM   #2446
Cal Weldon is offline Cal Weldon  Canada
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Ever think of building a Cornu Spiral horn? Now you can!
Second one done. Now the hard part.
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Old 11th February 2018, 06:56 PM   #2447
Lingwendil is offline Lingwendil  United States
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Ever think of building a Cornu Spiral horn? Now you can!
^ those are absolutely nuts.

I need to do a pair of these at some point.
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Old 11th February 2018, 08:26 PM   #2448
Cal Weldon is offline Cal Weldon  Canada
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Ever think of building a Cornu Spiral horn? Now you can!
Do it, your life is better for it. Go as big as you can as the improvement is hard to deny. Hopefully X will be here to model and help you through it.
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Old 11th February 2018, 10:35 PM   #2449
scott68 is offline scott68  United States
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You know, I think I will - The outcome should be interesting. I will use XRK's favorite speaker, Vifa TC9FD18-08 3-1/2 just so we can have a reference with the Cornu (and other enclosures.) Can I have some help with the starting parameters?
1. I have dollar tree foamcore as well as 24" x 24" 3/16 PVC sheets - Which one should I use for better sound? I'm not worried about the ease of use.
2. I will sketch the template and publish it for your advice but I need some info on these things:
a. Should I place the driver in the middle and see if we can decrease the harmonics by using two different channel lengths (if so, what should the difference in line lengths be? We can also vary the stuffing but it would be nice and lower bass if we can use the 2nd channel to help eliminate the harmonics.
b Or, should we do (a) as well as try to offset the driver in a different part of the "Cornu" spiral 1/3 the way from the center?
c What should the starting volume of the area around this driver be and what is the minimum depth behind the magnet including using 1/2" of felt behind the magnet.
d Of the two channel lengths, what should be our starting longest length line?
e I can't seem to find the patent number that XRK mentioned - Does anyone know how to view it?


Thanks

Last edited by scott68; 11th February 2018 at 10:38 PM.
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Old 11th February 2018, 11:13 PM   #2450
phivates is offline phivates  United States
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Cal doesn't do anything one could call "absolutely nuts."
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