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Old 21st January 2013, 09:34 AM   #1091
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by Carlp View Post
Man, XRK, I can't keep up with you. Nice work.
Thanks!
This was the fastest project I have ever done that produced a surprisingly good sound. (less than 2 hrs). And I didn't even have to crack open my dwindling supply of foam core boards.
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Old 21st January 2013, 08:13 PM   #1092
xrk971 is offline xrk971  United States
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I was looking a little closer at the dimensions of this cardboard bookshelf MLTL and it is almost matches the TABAQ which is probably why it works so well. Purely by accident though. The TABAQ has a 20 sq in cross section, I have 17.3 sq in. The TABAQ has a 30 in length not including the vent, same as mine. The TABAQ has a vent cross section of 2.4 sq in, I have 2.5 sq in with the 1.75 in dia tube. The TABAQ has a 3.8 in long vent, mine is 3 in long and inverted inside main body which probably has equivalent length that is slightly longer. The main difference is that I have my driver at the closed end whereas TABAQ is at 1/3 from closed end.
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Old 22nd January 2013, 01:58 AM   #1093
Carlp is offline Carlp  United States
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BTW, maybe cardboard as a prototyping material deserves it's own thread. I looked and there doesn't seem to be much about it on DIYAudio.
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Old 22nd January 2013, 07:21 AM   #1094
xrk971 is offline xrk971  United States
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You can start a cardboard thread if you want. Not sure if it is that much different than foam core.
It has interesting options in that cardboard is free and can be huge when you get a large shipment container. I find using foam core bracing or ribbing in cardboard works really well as the cardboard is not very good in axial compression like foam. Maybe hybrid like how I made the bookshelf MLTL. In which case it contains some foam and qualifies to stay in this thread.
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Old 22nd January 2013, 07:41 PM   #1095
xrk971 is offline xrk971  United States
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Default Specimen Petal Horn Speaker - Foam Core is Perfect for This!

I ran across these Specimen back loaded horn speakers that resemble the old style gramophones player horns. They make them out of recycled newspaper and glue mixed with dryer lint for a matrix. Instead of newspaper foam core is perfect for this, and instead of glue and lint, hot melt.

Click the image to open in full size.

This looks very interesting and would be a unique conversation piece more than anything. The bent shape of the 8 petals is critical to making the horn bend forward like that.

This may be one of my next projects. Has anyone here listened to one of these in person? They are in Chicago area. Alright, who's in on this one with me? We need to develop those patterns. You can see the one photo where they are hung out like laundry. There are 4 unique shapes.

Specimen's Hand-Crafted Horn Speakers Are Made from Recycled Newsprint and Dryer Lint | Inhabitat - Sustainable Design Innovation, Eco Architecture, Green Building

Last edited by xrk971; 22nd January 2013 at 07:44 PM.
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Old 24th January 2013, 06:18 AM   #1096
xrk971 is offline xrk971  United States
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Default Flatter is Better (FIB)

After some discussions on the BIB thread, I think I will try building the BIB but flattened so that it can be wall mounted. The wall and ceiling will provide even more boundary loading for the horn mouth. I will make the internal diagonal divider curved to accommodate the driver, and actually it should make the horn work even better. Below is the plan.
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Old 25th January 2013, 05:59 AM   #1097
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Quote:
Originally Posted by xrk971 View Post
After some discussions on the BIB thread, I think I will try building the BIB but flattened so that it can be wall mounted. The wall and ceiling will provide even more boundary loading for the horn mouth. I will make the internal diagonal divider curved to accommodate the driver, and actually it should make the horn work even better. Below is the plan.
Mmmm, you got me thinking about an in wall FIB with a 4" driver. Would that work? Approx. 48"x18"x3.5"
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Old 25th January 2013, 03:36 PM   #1098
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Quote:
Originally Posted by xrk971 View Post
After some discussions on the BIB thread, I think I will try building the BIB but flattened so that it can be wall mounted. The wall and ceiling will provide even more boundary loading for the horn mouth. I will make the internal diagonal divider curved to accommodate the driver, and actually it should make the horn work even better. Below is the plan.
My kind of build!
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Old 25th January 2013, 04:41 PM   #1099
IG81 is offline IG81  Canada
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Foamcore's pretty decent over small areas with enough thickness. One thing it can't do properly without all kinds of awkward bracing is a Karlson aperture.

Click the image to open in full size.

Even double-thick they move more than the driver's cone - I was not expecting much here to start with though. This is only a very rough test-box, so that's OK.

IG
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Old 25th January 2013, 05:39 PM   #1100
xrk971 is offline xrk971  United States
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IG,
I am not familiar with a Karlson aperture design. Do you have internal photos or a plan drawing? It sounds like there is a large pressure wave at the aperture if it moves that much. Nice work!
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