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Old 16th December 2012, 10:54 PM   #51
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Quote:
Originally Posted by Pano View Post
Looks very similar, in a simpler way.
It is a TL thou. Close to straight, A halfwave with driver mounted at ~50%.

Click the image to open in full size.

dave
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Old 16th December 2012, 11:02 PM   #52
xrk971 is offline xrk971  United States
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Actually 1/4 wave with end 31 is closed and end 30 is open with driver mounted at standard 1/3 from closed end.
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Old 16th December 2012, 11:05 PM   #53
Pano is offline Pano  United States
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Yeah, the Bose patent calls it a waveguide. One is meant to be 1/3L the other 2/3L. Multiple tubes are allowed. It does not seem to have the expansion of a horn, tho.
If end 31 is closed, then it's not the same thing, really. Hmmm....
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Old 17th December 2012, 09:32 AM   #54
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Default Work in progress

Ok, last tuesday I've finally found the foamcore board (not so cheap as at Dollar Tree) and last week-end I started the built.
I've scaled down to 50x50 cm the Cornu design (@planet10: thanks for the pdf) tracing a 14x14 grid, marking relevant points and joining them by hand.
Baffle and back are in poplar plywood (8 mm), 50x50 cm (20"), inner depth is 7,5 cm (foamcore strip height).
Can't wait to hear them...
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Old 17th December 2012, 12:48 PM   #55
xrk971 is offline xrk971  United States
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Great job Switters! Looks really nice in plywood.
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Old 17th December 2012, 04:37 PM   #56
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Quote:
Originally Posted by xrk971 View Post
Great job Switters! Looks really nice in plywood.
Thank you for spreading the foamcore Cornu idea

Er... I need to ask a question: I read that the throat area should be the same as the driver Sd parameter, right? In the Cornu there are two throat, I wonder if it is the single throat that should have area=Sd or if it is the sum of both throat (area=Sd/2)...
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Old 17th December 2012, 04:47 PM   #57
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The sum. If you find that it is too tight, trim some excess off to get the throat area opened up, I had to do that on my micro cornucopya after the hot melt glue hardened before I had a chance to set throat in correct location. I am glad folks are enjoying this build.
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Old 17th December 2012, 05:17 PM   #58
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Quote:
Originally Posted by xrk971 View Post
The sum.
Perfect, this is what i did.

Quote:
If you find that it is too tight, trim some excess off to get the throat area opened up, I had to do that on my micro cornucopya after the hot melt glue hardened before I had a chance to set throat in correct location. I am glad folks are enjoying this build.
Really enjoying. First time I used a hot glue gun.
To scale down the Cornu design to 50x50 cm I had to remove the initial segment (4-5 cm) of the spirals to get a 2 cm throat.

Thanks again
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Old 17th December 2012, 05:24 PM   #59
xrk971 is offline xrk971  United States
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Switters,
I like how you did it the manly way: triangle, dividers, ruler, pencil, and steady hands! I drew mine by hand using the grid method too. There is just something cool about laying down the spirals into a path that you drew yourself rather than a printout.
Looking forward to hearing your impressions of first sound. I forgot or did not see in your earlier post - what driver are you using?
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Old 17th December 2012, 07:02 PM   #60
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Default Micro Cornucopya (14 in) sound clips

I have been listening to the micro's for almost 5 days now (they are left on continuously when I am not listening) in the smaller bedroom, and I believe they are breaking in more, if that is possible with cheap no-name 2 in drivers. The sound has improved and the tonal balance, bass, and overall musical experience is now very rewarding to listen to. So much so, that I feel compelled to report how much I really like the micros and post a sound clip for folks to hear. The micro Cornucopya project has perhaps been the most bang for the buck and I can whole heartedly recommend it for those not wanting to make the bigger brothers. It is very cost effective and I would suggest ordering a set of Logitech S120's to take apart. I am actually using it with the Logitech's built in amplifier which according to specs is rated at 1.15 watts per channel. Even at this low power, the cornu horn expands the sound volume to fill the room and it is quite loud. One of the best things about the Cornucopya is its ability to sound good even at low volumes - the bass is still there. On some speakers the bass is only present at higher volumes, not so here. The speakers are about 4 ft apart and 4 ft high off the floor. The measurement was taken with a digital recorder with XY mic at about 6 ft away. For this sound clip, I am playing the amp at about 70% of max setting - quite loud. This is definitely the best sounding $10 set of speakers and amplifier that I have ever heard. When listening to the clip keep in mind that you are hearing tiny 2 inch drivers mounted in a paper faced foam box. I did not have a convenient project box to mount the Logitech amplifier in so I used an old baby wipes container with a terminal strip mounted on top,
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Last edited by xrk971; 17th December 2012 at 07:13 PM.
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