Foam Core Board Speaker Enclosures?

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#2,421
What speaker did you build and what driver? Baffle step depends on driver and size of baffle. For 8 ohm 85dB efficient drivers in a 6 in wide MLTL
Box that gets down to 50 Hz a starting point is 1 mH coil and 5 to 10 ohm in parallel and put that on series with driver positive between amp and driver. Adjust R to taste.
 
#2,422
^That seems best. Cut some additional strips, hot glue it to the back, use that as the reinforced area to place screws through.

I am using bolts - M5 12mm long - with hex nuts to secure my $1 driver to an OB of cardboard. Cardboard is more robust than foam board, but I see no reason why a nut a bolt mount would not work with foam.
 
#2,423
baco99 said:
Without the baffle step circuit, the bass falls steeply after about 250 Hz or so. Although the software says 95Hz. The high end seems to drop after 14kHz. I think the unencumbered midrange is really nice to hear.
Click to expand...

It is the open mid-range and vocals that sell me on the OB NOB builds with single wide-range drivers. There are some drivers that are 200-9000hZ that I am triying out.

I can even do without the bass and lower mid-range below 250, and my baffles with test tones verity this 200hz rolloff although I, too, am seeing some 50hZ - 95hZ response.

My tastes tend to be on the very esoteric side, and others here have used other adjectives. I would not expect many, or anyone, to prefer such a simple build.

But when I go back to my 1.5L enclosure that has much better bass response and greater slam, I can also clearly hear the boxiness, constriction and congestion. The sound has the quality of being caged, limited in a fashion.
 
#2,424
Some of the best cardboard I have found are the triple wall (two layers of corrugation) boxes that are used to ship heavy items like TV's and electric pianos. It even holds screws well with hardly any additional reinforcement.

If you want something really light but stiff try gluing thin cardboard into the outside of 3/4 in thick XPS foam sheathing insulation. Contact cement would work well. Then cut that board to make speakers.
 
#2,425
Slot Loaded Band Pass Sub made with XPS Foam - measurements

I built an all foam sub woofer using 1 in thick XPS foam sheathing. It is described in the sub woofer forum here http://www.diyaudio.com/forums/subwoofers/258433-light-air-slot-loaded-band-pass-sub.html- I took some measurements today in room with a miniDSP and REW. Measurements look good and it sounds very nice.

426175d1404104201-light-air-slot-loaded-band-pass-sub-slbpsub5-photo-construction.png


Measurement:

426384d1404222323-light-air-slot-loaded-band-pass-sub-slbpsub-no-tops-fr.png
 
#2,426
xrk971 said:
What speaker did you build and what driver? Baffle step depends on driver and size of baffle. For 8 ohm 85dB efficient drivers in a 6 in wide MLTL
Box that gets down to 50 Hz a starting point is 1 mH coil and 5 to 10 ohm in parallel and put that on series with driver positive between amp and driver. Adjust R to taste.
Click to expand...

I used the Vifa drivers in a plan detailed on the front page..
http://www.diyaudio.com/forums/full-range/232778-fostex-fe83en-right-small-box.html#post3427671
You gave me some advice about a baffle step circuit a couple days ago.
 
#2,427
nbriles2000 said:
I used the Vifa drivers in a plan detailed on the front page..
http://www.diyaudio.com/forums/full-range/232778-fostex-fe83en-right-small-box.html#post3427671
You gave me some advice about a baffle step circuit a couple days ago.
Click to expand...

I think you are referring to the folded path MLTL bookshelf size speaker? Can you please post some photos?
Glad it sounds good. When you put the BSC in the bass will sound a lot better. Also if you do use them on a bookshelf next to a wall the bass will also be enhanced.
 
#2,428
I had vowed to not pillage any more roadside signs until after the election (about a month away) but this was too good to pass up! Some pollster was lazy and planted eighteen signs all on a convenient half-block stretch. Their laziness was my motivtion for a good crop of coroplastt for (maybe) speakers. So far I've actually made a tablet cover, a failed cornu practice piece and some guinea pig houses

The presence of a political name here does not indicate either my approval nor disapproval for that candidate. Soldermizer does not endorse any political cause here, but does endorse nocturnal removal of annoying (and unlawful) roadside litter.
🙂

An externally hosted image should be here but it was not working when we last tested it.
 
#2,432
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#2,434
xrk971 said:
I knew you could make RC planes but never realized they looked this good and work this well. I should have realized, similar to speakers, the planes are clean and fast to build from scratch. Of course, hot melt glue is instrumental to this. What is cool is seeing all the different construction techniques to get curves, folds, joints, spars, ribs, bracing, etc. Plans are free...

Spitfire Build:
https://www.youtube.com/watch?v=gutkh30I-eM

Go to 4:15 to see it fly, and 9:50 to see acrobatic manuvers:
https://www.youtube.com/watch?v=5A_HJXmwLQ4

Main channel:
https://www.youtube.com/channel/UC9zTuyWffK9ckEz1216noAw
Click to expand...

I built a slab sided glider body and tail out of foam core board - 20+ years ago. I think I still have it in a box somewhere...
 
#2,438
What is needed to reach 20kHz? A different driver as this one is inherently limited to 15kHz open faced. It is a tradeoff with low end and high end. If you want 20kHz, not even a 2in dia CD will get there - you are in 1in CD territory. This is what Danley does in the Synergy. I am trying to do it with a fullrange driver so that the critical 500Hz to 5kHz is covered with a single driver. I am getting it well above 5kHz so I am happy with that.
 
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