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Old 22nd September 2013, 09:21 PM   #1021
xrk971 is online now xrk971  United States
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I have looked at a Cornu with a large driver chamber. This can be implemented with a secondary chamber larger than the main one abd locared underneath the main one on the back. The Cornu is quite forgiving of driver selection in general. The added volume will help the reduce the mids leaking out by settin g the high cutoff freq lower as that is proportional to throat area divided by chamber volume. It's easy enough to simulate it. Do you have a particular driver in mind?
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Old 22nd September 2013, 09:29 PM   #1022
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Could you not just block one of the horn paths at the mouth and call that an expanded chamber?
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Old 22nd September 2013, 10:08 PM   #1023
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No that doesn't work because the path to the mouth is then a TL and not just a chamber.
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Old 22nd September 2013, 10:25 PM   #1024
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I thought a TL had to have an opening.
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Old 22nd September 2013, 10:35 PM   #1025
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You can have a closed line - it is fact that length is there for sound to propagate and resonant modes exist.
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Old 23rd September 2013, 05:49 AM   #1026
hajj is online now hajj  Lebanon
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Quote:
Originally Posted by Cal Weldon View Post
I thought a TL had to have an opening.
Think about it as an expanding line with an opening that's horn loaded with 3 horns....

Well, I'll try to model something up on MJK worksheets and see how good it might behave with different drivers.
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Old 23rd September 2013, 10:03 AM   #1027
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It will be interesting to see the Cornu modeled on MJK. CAn you model 4 uneven length horns leading from common chamber?
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Old 23rd September 2013, 11:27 AM   #1028
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Quote:
Originally Posted by xrk971 View Post
It will be interesting to see the Cornu modeled on MJK. CAn you model 4 uneven length horns leading from common chamber?
I actually did some modelling for the cornu a few months ago, but forgot to post the results, I'll try to dig them up later tonight and post them.
But the models were made with double similar length horns, as this is one of the limitations of MJK's worksheets. IIRC, I modeled two different lengths so as to see each pair of horns contribution to the output, the downside being that the interaction between the differing length horns is not taken into account.

On the other hand, I think that modelling the BVR with equal length horn might be interesting, specifically because of the fact that the upper corner frequency of the horn will be lower, meaning less mids going through the horn which in turn will mean less stuffing. But this is all speculation for now. Let's see how it'll turn out..
More to come later today (hopefully)
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Old 23rd September 2013, 08:32 PM   #1029
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well i finished my second speaker today, as you can see i had a professional helping me this time and i absolutely love how these sound.. i never expected something i made (out of foamboard even) to sound this good!

All of this is already in earlier posts but to help out anyone who is considering to build these themselves:

I used the scaleable pdf from post #30, if you print it with adobe reader x or higher you can select poster, then it will print over multiple pages and you can tape them together quite easy.
If you want to scale it to another size, mind the 74x74, that's the size of the red line, the black lines are 70x70 in that pdf
After sticking them together i made holes along the lines to create a stencil, then just go over it with a marker and connect all the dots.
After cutting the strips i used a ruler to bend them, place the ruler on the place you want to bend it, press down on it, then bend the foamboard around it, move the ruler a bit and repeat. Gives you much cleaner bends then folding it by hand.
I hot glued the strips to the bottom and used a polyurethane glue for the top.

Well that about covers it can't wait to start building the next pair!

ps.

Big thanks to xrk971 and Cal!! couldn't have done it without your help.
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Last edited by Coen; 23rd September 2013 at 08:44 PM.
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Old 23rd September 2013, 08:53 PM   #1030
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Hey Coen,

Glad that your attempt worked out! Which poly glue did you use? In my first attempt the glue didn't hold, and now I am going for a second attempt.
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