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Old 21st January 2013, 03:07 PM   #451
jsouder is offline jsouder  United States
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Originally Posted by xrk971 View Post
Jsouder,
Those look great! You did a really precise job following the plan for the channels. The genuine wool hot off the back of your roving sheep takes the cake though! I am glad you ended up with a sound that you like. What channel depth did you use? Those $10 Tang Band buyouts seem to be having good success in the cornu. It also looks like the amount of stuffing you used worked out well too. Yours could be a prescription for those wanting to try a very low cost version of the cornu's. Like you said, you got love how good they sound for $50 with amplifier.
Congratulations!
The channels on that one are 2.5" deep, which with a throat of 0.5" is about 50% of the Sd area.

My next set will be 20"ers in a true spiral with 3.25" channel depth. With throats of 0.625", the area will about equal the Sd. Here's the start:
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Old 21st January 2013, 03:32 PM   #452
xrk971 is offline xrk971  United States
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Jsouder,
Those 20 in true spirals look really good. Can't wait to hear how they sound.
Nice job.
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Old 21st January 2013, 06:11 PM   #453
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Glowglass, I can't see the pictures of your design. Any idea why not?
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Old 22nd January 2013, 12:52 AM   #454
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Because I am a bit clumsy on the computer. Also I joined a few years ago as a lurker it is only now that I started dealing with the inner workings of this list.
Maybe my pics are too big in pixel count?
I see the design in my post #447, but the pictures of the driver are not up in post #450.
All pics are in my album named "electro aucoustics". Can you see them there? I made it public to members.
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Old 22nd January 2013, 02:12 AM   #455
iko is online now iko  Canada
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The links are somehow broken. Here's a link to the gallery.

electro aucoustic - My Photo Gallery
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Old 22nd January 2013, 04:41 AM   #456
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Thank you for the link ikoflexer!
I need to redesign my approach or use smaller drivers. My drivers Sd is 490 square cm and the horn throat slots are way to narrow in the drawing I posted earlier.
Using the "Puck" I can play with 6 throats instead of 3 or 2 which helps. I like very much to arrive at the solution - coming back later.........
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Old 22nd January 2013, 07:09 AM   #457
xrk971 is offline xrk971  United States
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Glowglass,
You may be able to run with throat area as small as 0.5x Sd if you have the ratio of Sd to Vol for driver chamber large enough for cutoff freq. You may want to consider a double sided (2 horn layers separated by divider) to get a depth large enough. Assuming 4 in deep per side gives 8 inches or 20 cm deep. Assuming throat area is half of Sd, 3 throats, the throat width at the chamber is about 0.8 inches wide. I think that is manageable. You will have twice the work to build a double layered horn but then again, you have one huge driver. The double layer is necessary to prevent having a channel depth that is too tall which may buckle.
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Old 22nd January 2013, 03:49 PM   #458
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Quote:
Originally Posted by glowglass View Post
Thank you for the link ikoflexer!
I need to redesign my approach or use smaller drivers. My drivers Sd is 490 square cm and the horn throat slots are way to narrow in the drawing I posted earlier.
Using the "Puck" I can play with 6 throats instead of 3 or 2 which helps. I like very much to arrive at the solution - coming back later.........
Glowglass, that is a very ambitious and challenging project to pull off with a 12" driver. I would imagine 8" to be the cutoff for a design like this. I really like the asymmetrical shape of your plan because it might solve potential diffraction issues, and if it's deep enough (~8") you may also be able to avoid a dip in the upper mids from rear-wall reflections. But it will still be a MASSIVE speaker! Back when I was considering a 3' x 3' cornu for my W5-1611's, it seemed like a viable plan until I measured 3' x 3' on my wall. All of a sudden I realized that 9 square feet of baffle was actually kind of BIG...
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Old 23rd January 2013, 01:15 AM   #459
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Hey, very workable suggestions x and chaz! The double layer and the Sd/2 could save me.
Yes I like the off center place for the driver from past experiences. Would have gone closer to the top right corner,but that will mess up the horn paths. Need some time to fiddle with the horn spiral making the throats little bigger without ending up with horns too short. Need to work the math and learn to use HOLMImpulse to get some data on the drivers. Ideas are flying around the brain,but no cigar yet. Also thought about a double layer with Voight pipe style 30% access holes. Could the Puck be drawn with horns starting at zero/ middle?
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Old 23rd January 2013, 06:10 AM   #460
xrk971 is offline xrk971  United States
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Glow,
The puck as it is currently drawn is based on the Cornu function which doesn't go to zero - it asymptotically approaches a finite radius which defines the driver chamber. I think the easiest way to modify it is to do what you have done - hand draw on a grid. Both of my Cornu's were made this way. You are indeed taking on a super ambitious project - we will all be in awe when it is done. I hope you do it - it will be spectacular.
Good luck.

Regards,
X
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