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Ever think of building a Cornu Spiral horn? Now you can!
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Old 11th April 2014, 04:34 PM   #1561
edodo is offline edodo  France
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Yup it's undersized, as I could have the board fairly cheap. Going bigger meant lots of wasted woods. I wanted to try out for my Cornu with a smaller model and easy to source 60cm boards...

The front box driver is a good idea! I'll give that a thought on my next cornu!

I think the channel left before bifurcation is 12 cm to 10 cm. Thanks for the sim, X!!!
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Old 11th April 2014, 04:41 PM   #1562
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by gtoro View Post
Ok these are the parameters, using foam 5mm for front and back and 0,3mm for horn with this kind of luodspeaker is correct a dimension of 50cmX50cm how deep had to be the internal foam? thanks for any suggest and information
Click the image to open in full size.
I would go for a 27.5 in x 27.5 in x 4.0 in depth. The 50 cm is too small I don't think the magnet and basket will fit.
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Old 11th April 2014, 07:25 PM   #1563
gtoro is offline gtoro
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Many thanks and sorry for my bad english... I will try it
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Old 11th April 2014, 08:49 PM   #1564
xrk971 is offline xrk971  United States
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Ever think of building a Cornu Spiral horn? Now you can!
Edodo,
The sims of the Lcao F6 in a 24 in Cornu are not good. I am afraid you will most likely be disappointed with the performance as there is no bass below 100 Hz - sorry to bring bad news...

Here is the sim in a 24 x 4 deep Cornu with all channels intact:

Click the image to open in full size.

Here is with only 5 cm of the initial channels remaining in a 24 in x 4 in Cornu - not very pretty looking:

Click the image to open in full size.

If you went up to a 36 in x 4 in size it looks better but I am not convinced the driver cutout will fit and also the bass performance looks like it is still needing more volume:

Click the image to open in full size.

I think the ideal size for the F6 is a huge 40 in x 4 in deep Cornu - but you will get bass extension down to 35 Hz (-10 dB):

Click the image to open in full size.

Here is the cone displacement for the 40 inch:

Click the image to open in full size.

Here is the impedance for the 40 in:

Click the image to open in full size.

If you do build the 40 inch version - it will indeed sound very impressive with the 95 dB bass efficiency. That us very loud at 1 watt and will bother neighbors and vibrate walls and windows badly at 5 watts (don't exceed this to stay below xmax).

I don't think anyone will ever do this but if size were no object, you could even make it 48 in x 6 in deep - a whopping 16 square feet of baffle. A standard 4x8 ft sheet of plywood will suffice for one speaker's front and back, albeit only 1/4 in thick can work... Here is what you get - a solid bass extension down to 33 Hz (-3dB):

Click the image to open in full size.
Attached Images
File Type: png Cornu6a-24x4-Lcaof6-freq-1m.png (31.0 KB, 465 views)
File Type: png Cornu6a-24x4-shortened-Lcaof6-freq-1m.png (37.1 KB, 465 views)
File Type: png Cornu6a-36x4-Lcaof6-freq-1m.png (35.2 KB, 468 views)
File Type: png Cornu6a-40x4-Lcaof6-freq-1m.png (36.6 KB, 465 views)
File Type: png Cornu6a-40x4-Lcaof6-displ.png (29.3 KB, 454 views)
File Type: png Cornu6a-40x4-Lcaof6-Impedance.png (31.7 KB, 454 views)
File Type: png Cornu6a-48x6-Lcaof6-Freq-1m.png (18.4 KB, 455 views)

Last edited by xrk971; 11th April 2014 at 09:01 PM.
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Old 13th April 2014, 08:28 AM   #1565
edodo is offline edodo  France
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I guess I will do a bass reflex then. The 24" cornu I will source a cheapo 3,5"
By the way, I really like the way the LCAO sounds. Very extended and smooth medium...
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Last edited by edodo; 13th April 2014 at 08:31 AM.
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Old 15th April 2014, 03:57 PM   #1566
Coen is offline Coen  Netherlands
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Well i finally got around to starting a new pair of cornu's I'm going with 61cm/24inch mdf 5mm thick, a foam core of 8cm deep and ordered a pair of fostex fe103en drivers.
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Old 15th April 2014, 04:00 PM   #1567
Cal Weldon is offline Cal Weldon  Canada
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Is 8 cm deep what X recommended?
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Old 15th April 2014, 04:15 PM   #1568
xrk971 is offline xrk971  United States
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I don't think I have ever run a sim of an FE103en in a 24 inch. You may have clearance issues with the basket and the driver chamber on a 24 inch. I know Prezden had issues with the Tang Band W4 bamboo on a 24 incher. Consider a 27.5 inch cornu. Probably 27.5 x 4.5 inch should work - similar to FF125WK.
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Old 15th April 2014, 05:06 PM   #1569
Coen is offline Coen  Netherlands
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Quote:
Originally Posted by Cal Weldon View Post
Is 8 cm deep what X recommended?
Didnīt want to bother him with yet another sim, i guess he would recommend 4inch - 10cm with 24 inch. But 8 cm will be close enough for me

Quote:
Originally Posted by xrk971 View Post
I don't think I have ever run a sim of an FE103en in a 24 inch. You may have clearance issues with the basket and the driver chamber on a 24 inch. I know Prezden had issues with the Tang Band W4 bamboo on a 24 incher. Consider a 27.5 inch cornu. Probably 27.5 x 4.5 inch should work - similar to FF125WK.
The w4-1320sif was my preferred driver, but i had problems getting it here for a reasonable price / in a decent ammount of time. The basket should be fine, the mounting hole on the drawing of the 70cm cornu is 10cm and the driver chamber is 12cm. Scaled to a 61cm cornu that would be a 8,7cm hole with a 10,5cm chamber. The hole diameter for the fe103en is 9,2cm, so it should fit the chamber easily. I also know the xmax of the fe103en is limited (0,6mm), but i read multiple posts of people saying they didnīt run into any problems exceeding it. I also read a review of a cornu with a fostex fe103sigma (0,35mm xmax), which was very positive. Anyhow, this gives me a chance to try something new. And in the worst case i'll end up with a set of fe103en-s for another project, which isn't that bad.

Last edited by Coen; 15th April 2014 at 05:32 PM.
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Old 15th April 2014, 06:24 PM   #1570
Coen is offline Coen  Netherlands
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Found Prezdens post, he made a 22inch cornu. (with a 24inch front) That would mean a 9,4cm chamber and the tang band w4 diameter is 9,5cm. So i can imagine he had problems fitting it, but i think the fostex will fit.
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