Foam panel speakers

sealy

Addicted Member
At first I was dubious about the idea of attaching a one inch diameter exciter to the back of a one inch thick 3 ft. x 2 ft panel of extruded polystyrene foam. I certainly didn't expect much. Man was I wrong! The sound emitted was so clear and accurate that I was floored. I ordered three more exciters from Parts Express and ended up with two panels, each with an exciter. They were powered by my trusty Sansui receiver. Although the panels weren't properly positioned - the best place for them is hanging free from a ceiling - they still sounded terrific. I placed them about 7 feet apart and toed them in slightly. I was amazed at the fact that they had some tangible bass response, which probably in the region of 50hz. I paired them up with an Orb Super 8 subwoofer. Small but mighty. I turned the bass volume switch up just a bit and set the crossover point at 80 hz. It matched perfectly with the panels. With a live jazz recording playing I determined that the sound was the very best I'd ever heard. The piano had weight, the drummer thumping the bass drum was very lifelike. The decay of a cymbal strike was longer and more perceptible than any conventional speaker I've heard. The sound of a piccolo is something that sounds almost ear-splitting with most speakers. It was clear as a bell with the panels. I would post a photo, but there isn't much to see save two green panels resting against some tower speakers. Listening to them is an incredible experience. Eventually I will have 4 panels in strategic positions so that the experience will be similar to that of a surround sound system.
 
An old but good concept. My dad made a set of these in the mid 70's using a rectangular coil and permanent magnets. As I recall they sounded quite nice, especially considering they were made from scrap foam, balsa wood, and Edmund Scientific surplus magnets :)
 
That youtube video was fun to watch, got to applaud that guy's enthusiasm and persistence!

Of course, keep in mind he is more of a general purpose tinkerer than an audio expert. He spends a lot of time optimizing for frequency response, but there's no info about distortion, power bandwidth, or dispersion. I'd love to see a polar response plot for say 1kHz, 5kHz, and 10kHz, and a few distortion measurements. Distortion versus amplitude at say 100Hz, and 1000Hz would be pretty telling .

I would not go into this expecting miracles. Theres a reason this kind of speaker isnt more popular.
 
I think it's more than a little weird how he "demonstrates" speakers on youtube.

Like the overworked headphone driver in my laptop is going to be able to inform me on how good that sounds.
If you go to his video "world's best speakers" and plug it into your stereo the demonstration is quite good.
but I'm still hearing my speakers reproduce what his microphone picked up

Did you watch the vid suggested all the way through on a decent two channel stereo? Not the vid linked in post #3, but his follow up vid.
 
Did you watch the vid suggested all the way through on a decent two channel stereo? Not the vid linked in post #3, but his follow up vid.

Yes and I've watched several of his videos, both speaker and non-speaker related. The one where he uses a constrained layer of paintable waterproofing material between two thin sheets of plywood is especially interesting.

But a youtube video is still a reproduction of a recording and can't really tell you how another speaker sounds.
 
So, say we accept back wave reflections. Why not. It works very well with O/B, big panels, corner loaded horns, Bose. Whatever.
And we can deal with limited bass response. But it appears the response may be far better than most other single driver full range speakers. No xover sounds appealing. And low cost too.
And looking at a piece of art hanging on the wall has it's attraction also. Say in the dining room, or the wife's fancy off limits living room, in the bedroom over the headboard? Assuming they work 3 inches from the wall.
I would like to see more research. And hear them. I'll will most likely try it.
 
When I was in high-school in the early 80's, a good friend's father had a pair of Bertagni speakers. These are 2-way speakers using Styrofoam panels. The were powered by an SX-1010, and I recall them sounding good but somewhat light on the lower bass, which isn't really unexpected. I'd like to hear a pair now, just for fun. I'm also curious as to how the flat panels speakers mentioned in the video compare to something commercially produced, such as the Bertagni BES speakers.
 
I'd like to hear them and treated like Maggies. For example, proper distance from front wall with diffusion behind the panels. I wonder how they would sound mounted in frames like Maggies. I might be the one to try it out.
 
I was wondering if it's possible to use more than one transducer per panel? Would it be possible to get better frequency response and efficiency if you used four of these wired series parallel for 8 ohms and make a really tall panel? Also, how are these transducers attached to the panel? Cement of some sort? It seems to me that they would be more effective if they were attached from the back of the transducer to a rigid frame and only have the linear motor attached to the poly so the diaphragm could have more excursion and produce more bass.
 
At first I was dubious about the idea of attaching a one inch diameter exciter to the back of a one inch thick 3 ft. x 2 ft panel of extruded polystyrene foam. I certainly didn't expect much. Man was I wrong! The sound emitted was so clear and accurate that I was floored. I ordered three more exciters from Parts Express and ended up with two panels, each with an exciter. They were powered by my trusty Sansui receiver. Although the panels weren't properly positioned - the best place for them is hanging free from a ceiling - they still sounded terrific. I placed them about 7 feet apart and toed them in slightly. I was amazed at the fact that they had some tangible bass response, which probably in the region of 50hz. I paired them up with an Orb Super 8 subwoofer. Small but mighty. I turned the bass volume switch up just a bit and set the crossover point at 80 hz. It matched perfectly with the panels. With a live jazz recording playing I determined that the sound was the very best I'd ever heard. The piano had weight, the drummer thumping the bass drum was very lifelike. The decay of a cymbal strike was longer and more perceptible than any conventional speaker I've heard. The sound of a piccolo is something that sounds almost ear-splitting with most speakers. It was clear as a bell with the panels. I would post a photo, but there isn't much to see save two green panels resting against some tower speakers. Listening to them is an incredible experience. Eventually I will have 4 panels in strategic positions so that the experience will be similar to that of a surround sound system.

I recently gained interest in making some of these in larger sizes than most I see. Thinking of making ‘em as “two way” using larger panels for the mid-bass and smaller panels for midrange to treble. Was also thinking of making some large subs to go with them, similar to the Pass “el pipe-o”.
My reason for thinking about these foam panels are:

1) They’re cheap.
2) They can be made big and they’re light enough to hang up from the ceiling, a couple feet out from the wall.
3) They’re cheap!

Has anyone else made up a set of these that actually sound good? Thinking that by choosing the proper “exciters” and using larger size panels and good crossovers, these could work well in a large room.

Not doubt, that since these are an open baffle speaker and some people don’t seem to understand that, these would need to be treated like other open baffle, flat speakers (think Maggies), and placed a proper distance from a wall to sound decent.
Maggies, for instance, sound best placed a -minimum- of two feet out to sound OK. Further out is better.

These speakers are cheap enough that somebody must have built some bigger ones that they like the sound of. Opinions?
 
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