Thought I'd share this - cardboard U-frame.

[chris661]

This is a quick mess-about, not for any kind of scientific testing purpose.

Anyway, I had some cardboard lying around, and 4 Visaton FRS8 speakers, so I decided to make a pair of near-field U-frame OB speakers. The amp you can see powering them was gutted from a pair of PC speakers, so it fits the bill nicely.

The sound

I'm not going to beat about the bush - it's not brilliant. The treble isn't quite right due to things like comb filtering, the bass is almost non-existant. Even so, it's not bad for what it is. I put them together with no calculations. The height for the sides was the height of the shoe-box I used, I only doubled the baffle thickness because I didn't want them to fold in half. But hey, it was fun - they don't go that loud, but they sound Ok for what they are, which is a half-hour build with the stuff in front of me.

If you've done anything like this, feel free to post it.

Chris

PS - I held it together with cello-tape

[kenpeter]

Those might go good with my styrofoam Smith horns.
Well, I've only actually built one half of the proposed
pair yet. But it works!!!

You need some cardboard plate lenses to widen the
dispersion???

[chris661]

Currently, no, I'm enjoying the crudeness of my creation, but, in a few months...

[ra7]

how are the speakers mounted on the cardboard? is it thick enough to hold them? don't they want to fall down?

[chris661]

I doubled up the cardboard, and sandwiched the drivers between it. Then I added "feet" at the back, which double as the U-frame. It only really covers the bottom driver, so the top one is a simple OB.

Chris

[pjanda1]

I once built some test OB's with a pair of ikea boxes. I bet a fair number of us have done such things. Your pair appears to be much more thoroughly executed than mine was. Screws and everything!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[chris661]

Those are screws screwed directly into cardboard.

I can't buy ikea stuff yet - no space to put it all...

It's nice to know I'm not the only one.

Chris

[enigmaticEntity.]

About a year ago I built some car "back shelf" speakers out of some 3'' crappy 2W radio speakers, in cardboard enclosures with ports and bracing .

The "subwoofer" was a 5'' by 3'' whizzer cone speaker with a metal ring glued on the whizzer cone. This was placed face down on the back shelf, which resonated nicely.

I made the 3'' driver more compliant by wetting the paper surround and making it thinner and more flexible.

The system actually sounded half-decent with bass down to 70Hz, albiet with a 2W old tape/radio modded to take input from a 3.5mm jack...

Pity I can't put up any photos (car is gone, with the speakers). I wonder what the wrecker/scrap metal, etc. person thought when they saw them...

And yes, they were held together with cellotape.

@chris661: Yours look better than mine did .

[chris661]

Fantastic - should we start a cardboard speaker thread?

With Christmas comming up, looks like there'll be many more cardboard speakers on their way.

[Nanook]

you may not have noticed, but lots have cut their teeth on OB speakers. They can be quite a revelation. One thing I might suggest that you do is to actually make them a "U" from top to bottom, and make them deep enough to help with bass reinforcement.

If the drivers are suitable, a lot have fun can be had with OBs and are still my favourite type. Boxes always sound like boxes. OBs sound like nothing.

An interesting comparison was done between the Wharfedale SB3 loudspeakers and the Quad ESLs. The point made was that both had advantages, but the sound was closer than one might think. This was a contemporary comparison, not something done from memory but a true side by side.