Foam Core Board Speaker Enclosures?


cool- I'll keep an eye out for it. Not surprisingly, I'm not thrilled with the PVA or the water based contact cement. Just not aggressive enough for doing a whole sheet at a time unless I wanted to make a proper sheet clamping system. Solvent based contact cement is only available in small containers here, due to the already unpleasant air quality...

I may just stick with the 3M type 90 adhesive as it was sufficiently aggressive to grab every edge.
 
I've been using it since it came out in the '70s to make foam core board architectural structures, scaled down speakers and prototype horn designs. Of course it makes quick, clean work of paperback and hardbound book damage and just glued back a partially unraveled TP tube used to hold a folded up printer power cord.

Just applied glue, squeezed it back together with my fingers, wiping excess glue off as I went and it was back in duty. Bonding a large number of loose pages back to the binder/cover OTOH requires enough glue to require some mild clamping while it dries though.

For large panel laminating, I just lay one piece on a non-skid surface, run a bead around inside the perimeter a bit and zig-zag/whatever some in the open area and 'slide' the other piece around on it a bit to somewhat distribute it, then lay a piece of 3/4" MDF or similar that's at least as large on top to 'clamp' it.

GM
 
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I made a Karlsonator in 0.53X scale with duial Vifa's. They sound fantastic!
http://www.diyaudio.com/forums/full-range/237948-speaker-kicks-butt-large-spaces-21.html#post3560234
359935d1373734918-speaker-kicks-butt-large-spaces-karlsonator-6s.jpg

Highly recommended!
 
here are Greg B's original plans for his Karlsonator series

these are downloadable as nice 1/4 size plans

If I'm not mistaken (?) XRK971 is scaling relative to the Karlsonator 12

Karlsonator Six https://plus.google.com/photos/1005...5578916065853178818&oid=100545049816297868412

Karlsonator Eight https://plus.google.com/photos/1005...5685712049966245090&oid=100545049816297868412

Karlsonator Twelve https://plus.google.com/photos/1005...5680514503473417410&oid=100545049816297868412

my Karlsonator Six also sounds nearly the same 90 degrees off horizontal axis as on - Karlson was a genius.
An externally hosted image should be here but it was not working when we last tested it.
 
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Darkstar,
That's correct, I used the Karlsonator 12 plan and scaled it so that the max height was exactly 15 in so that I could get 2 full length panels on a 30 in x 20 in FC sheet. The scale was 0.53X in most dimensions except overall length was reduced for this reason. I will post a sketch of the as-built one soon. 12 rectangular pieces from 2 sheets of FC per speaker. Easy to cut with long straight edge and xacto.
 
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I took some measurements of the Karlsonator - post #223 in the "Kicks Butt" thread. Looks pretty good and confirms the bass punchiness and overall balance of speaker, which by the way, sounds really good with classic rock like Dire Straits, and jazz where there is a bowed double-bass.

360257d1373877583-speaker-kicks-butt-large-spaces-karlsonator-0.53x-tc9fd-freq-0.9m-measurement.png


Ignore the drop off at 10kHz, my pc soundcard has a high freq limit.
 
In view of the results obtained by xrk971 on this little Karsonator cabinet with two speakers mounted in it I will ask again the question I asked a few months ago. How would one of these go with two Fostex FF225WK mounted in a correctly sized enclosure. I have four of these waiting to go into something!!! At the time I asked the idea was sort of rubbished. If you think this is possible would it be possible to cut one of the speakers reasonably low and then leave the other going quite high to a Karlson type tube tweeter. I have heaps of nice bamboo
up to fairly large diameters and long distances between the nodes - would this be suitable for a tube? Thanks for any help.
jamikl
 
Thanks for your trouble xrk971. I think, from what I have seen on the three threads here that the Karlsonator might be a bit smoother. I do wonder how rolling off one of the FF225WKS early would affect that. I think I would like them inline, like your small one, rather than side by side. Can you easily simulate them mounted both ways. I guess that if side by side was ok I wouldn't want to roll one off - might give strange results.
jamikl
 
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Dual FF225WK in 1.24X Karlsonator

Thanks for your trouble xrk971. I think, from what I have seen on the three threads here that the Karlsonator might be a bit smoother. I do wonder how rolling off one of the FF225WKS early would affect that. I think I would like them inline, like your small one, rather than side by side. Can you easily simulate them mounted both ways. I guess that if side by side was ok I wouldn't want to roll one off - might give strange results.
jamikl

I am sure glad you asked me to sim this because it is simply amazing what it can do! :) The sim is posted in the Kicks Butt thread here: http://www.diyaudio.com/forums/full-range/237948-speaker-kicks-butt-large-spaces-23.html#post3562113

Here is a teaser of the freq response at 3 meters:
360266d1373889235-speaker-kicks-butt-large-spaces-karlsonator-1.24x-dual-ff225wk-freq-3m.png


This may be the Holy Grail of the Karlsonator - a true 30 Hz performer that throws a flat bass shelf far away.