Sorry if this is too late. It's a fast expanding thread.
Theoretically, foamcore board is not as good in blocking sound wave as wood (or other dense materials). So, a foamcore enclosure must be somewhat more leaky than ordinary wooden box.
I think, we can take this as an advantage (or at least options) for arranging the overall performance of the speaker -- can it be cardioid, or aperiodic ? I'd say why not.
Or, has it been brought up already?
Theoretically, foamcore board is not as good in blocking sound wave as wood (or other dense materials). So, a foamcore enclosure must be somewhat more leaky than ordinary wooden box.
I think, we can take this as an advantage (or at least options) for arranging the overall performance of the speaker -- can it be cardioid, or aperiodic ? I'd say why not.
Or, has it been brought up already?
I wish I had a beaver helper. In that case, your 36 inch Cornu qualifies. We also have sound clips (or videos) so know it sounds great.
For scoring, I'd say a 40% "Hardship" category, rated subjectively, would cover the differences in shop and drivers. If you had your assistant make it at your pro woodshop and used hartleys and le8ts, you get zilch on the Hardship but have a pretty good chance of 100% on the other 60 points. If you made it with your teeth in a phone booth (nice) then you get full hardship score but are definitely disadvantaged as far as results for the other 60 points.
Ok, if Cal is entering the Cornu, I want to enter my (0.4x) Karlsonator I built in 4.5 hours, see post 178 on this link for proof. Now I just have to post a sound clip. 
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-18.html
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-18.html
Quick Cheap and Dirty Speaker Challenge thread
You guys need to post your entries to the correct thread if you want to be part of the Quick Cheap and Dirty (QCD) Challenge:
http://www.diyaudio.com/forums/full-range/256437-quick-cheap-dirty-speaker-challenge.html
@Webber,
Nice entry! I should have entered mine too but you beat me to it!
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You guys need to post your entries to the correct thread if you want to be part of the Quick Cheap and Dirty (QCD) Challenge:
http://www.diyaudio.com/forums/full-range/256437-quick-cheap-dirty-speaker-challenge.html
@Webber,
Nice entry! I should have entered mine too but you beat me to it!
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Single Speaker Stereo (SSS)
Based on the technique described by Elias in this thread (http://www.diyaudio.com/forums/full-range/257110-master-nagaoka-tetsuo-explorations-matrixed-single-stereo-speakers-2.html#post3947394), I tested this method out using separate boxes and liked it enough to build a dedicated box.
I decided to make it with 45 deg angled side firing drivers and used the matrix circuit described here:
I then decided on convenient sizes to make it out of foam core with three Vifa TC9FD's. I settled on a 15 in tall x 15 in wide x 5 in deep box which turned out to be 12.3 liters. I designed a bass reflex port to give about 70 Hz extension. The port ended up being 4.5 in wide x 1.5 in tall x 5 in long. Here is the predicted response modeled with three drivers in parallel. In reality they are not parallel so efficiency will not be as high but response should be similar in shape.
Here is the inside of the box built with orange and blue faced FC.
Here is the finished box driven by a TDA7297 chip amp. Note that a class D amp cannot be used in a matrix tied load.
It sounds really good and I am enjoying the sound and this is a simple enough project once you figure out the matrix wiring. I recommend it - a lot of fun and can be used in spaces where you can't have two speakers. There is clear stereo imaging as the sound reflects off the side walls and forms a phantom image. The 70 Hz tuning did the trick to give it just enough bass to sound good with many types of music.
Based on the technique described by Elias in this thread (http://www.diyaudio.com/forums/full-range/257110-master-nagaoka-tetsuo-explorations-matrixed-single-stereo-speakers-2.html#post3947394), I tested this method out using separate boxes and liked it enough to build a dedicated box.
I decided to make it with 45 deg angled side firing drivers and used the matrix circuit described here:
An externally hosted image should be here but it was not working when we last tested it.
I then decided on convenient sizes to make it out of foam core with three Vifa TC9FD's. I settled on a 15 in tall x 15 in wide x 5 in deep box which turned out to be 12.3 liters. I designed a bass reflex port to give about 70 Hz extension. The port ended up being 4.5 in wide x 1.5 in tall x 5 in long. Here is the predicted response modeled with three drivers in parallel. In reality they are not parallel so efficiency will not be as high but response should be similar in shape.
Here is the inside of the box built with orange and blue faced FC.
Here is the finished box driven by a TDA7297 chip amp. Note that a class D amp cannot be used in a matrix tied load.
It sounds really good and I am enjoying the sound and this is a simple enough project once you figure out the matrix wiring. I recommend it - a lot of fun and can be used in spaces where you can't have two speakers. There is clear stereo imaging as the sound reflects off the side walls and forms a phantom image. The 70 Hz tuning did the trick to give it just enough bass to sound good with many types of music.
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I just switched to a bigger 45 w/ch class AB amp (Yamaha RX360) and it sounds much better. The small TDA7297 was clipping at high freq transients when wired in matrix mode. Not sure what was causing that but the bigger amp fixed the problem. Might be a problem with insufficient power supply rail cap. This setup seems to tax the amp because the chip amp was running pretty hot even at lower volumes.
I did not realise foam core is available with so many colors I may have to start sourcing availability in my part of the world. I have not read foam core thread troughoutly , but what is the primary intended application for this material ? Is it for house construction, or for artistic handicraft, or something else ?
Especially those 45 degree angles seem to go very smoothly with that material
Now I have a controversial idea
First make a wooden enclosure, not caring about the joint finesse, then cover it with that foam core. Similar to veenering process. Could easily make a hexacone shaped box, for example.
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Elias,
Welcome to the world of foam core!
It is used primarily as backing material for posters and pictures. There is a group of RC airplane model builders who use it to make flight aircraft. It is very light yet strong for its weight and has ability to be shaped into smooth curves like airfoils or curved wall speaker boxes. So you are not limited to rectilinear boxes anymore. The colorful boards do make it look interesting. You mention covering wood with foam core - folks here usually want to cover the foam with wood veneer because people think the foam doesn't look good or like a real speaker - interesting that you are the first to suggest going the other way! I like how it looks and I like the ease of fabrication. I built the SSS in 2 hours so it lets me test out an idea very quickly.
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Welcome to the world of foam core!
It is used primarily as backing material for posters and pictures. There is a group of RC airplane model builders who use it to make flight aircraft. It is very light yet strong for its weight and has ability to be shaped into smooth curves like airfoils or curved wall speaker boxes. So you are not limited to rectilinear boxes anymore. The colorful boards do make it look interesting. You mention covering wood with foam core - folks here usually want to cover the foam with wood veneer because people think the foam doesn't look good or like a real speaker - interesting that you are the first to suggest going the other way! I like how it looks and I like the ease of fabrication. I built the SSS in 2 hours so it lets me test out an idea very quickly.
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Or near field enclosures for mounting on headrest of that favorite recliner?
One could build miniature Nautaloss spiral TL that you wear as headphones and you could end up looking like Princess Leia
. It would actually sound good though as the back wave would be absorbed like wearing an infinite baffle.
Just ordered a pair of the Vifa TC9FD and I'm planning on making the MLTL from the front page! Been looking to build some full rangers and I think this is probably the cheapest way to get my feet wet!
Does anybody know if there is a subwoofer that pairs especially well with these drivers or this MLTL in particular? Will be in a small bedroom in an apartment so I wont need a whole lot!
Does anybody know if there is a subwoofer that pairs especially well with these drivers or this MLTL in particular? Will be in a small bedroom in an apartment so I wont need a whole lot!