We've seen a number of unusual speakers before, such as the Whamodyne glass speakers or Solid Acoustics' dodecahedron speakers, but concrete speakers are definitely something new. It's definitely not a very popular material for audio systems, but Israeli designer Shmuel Linski would like to change that with his "Exposed" concrete speakers, each of which weighs 123 pounds (56 kg). They're just one part of his line of unusual creations, that include a concrete coffee maker and a concrete canoe.
Most speaker casings are made of solid wood or MDF (medium-density fiberboard), while the cheaper models utilize plastic, but non-resonating concrete doesn't seem to be the right material for transmitting sound. "When concrete meets sound, it might distort the sound because the concrete is very stiff," Linski explains. "The speakers might therefore sound strange." Why make loudspeakers that sound strange? The designer gives a rather unclear explanation, saying that the Exposed speakers are capable of "invoking a sense of nirvana for concrete lovers and audiophiles."
To design the speakers, Shmuel used horn loudspeaker technology. The driver, located at the top of the speaker, is linked through a 96 cm (38 in)-long externally-lined pipe, with a large horn-shaped bass port at the bottom resembling a megaphone.
The concrete speakers are Linski's graduation project at Shenkar College of Engineering and Design in Ramat Gan, Israel. There's no word on any possible commercialization of the product.
His other concrete projects are also unusual. The "espresso solo" is an espresso-making machine in a concrete casing, and the Orca concrete canoe was made for a concrete canoe-building competition held last year in Israel.
More information about Shmuel Linski can be found on his personal website.
They were so efficient that the compression waves from the speakers were so great that they could bring on feelings of extreme nausea and even a heart attack.
Needless to say they had to be limited in their volume
LeW in Sydney
And concrete speaker cabinets have been made - well before Neil Armstrong walked on the moon.
But I do have a thing for casting concrete into glass smooth molds - as the grain size of the cement is SOOOOOOO fine, that it takes on a glass surface finish.
Very nice.
AND for the record, people have made ferro cement aircraft too. I have seen the ferrocement hang glider made and flown.
The ASCE National Concrete Canoe Competition (NCCC) http://content.asce.org/conferences/nccc2010/
The last thing you want in a speaker system is resonance (an exception is the ported speaker where resonance is used to damp the woofer at its natural resonant frequency thus preventing it from destroying itself and smoothing out the bass).
You want resonance in a musical instrument because you\'re CREATING sound but any resonance in the speaker system will colour the sound in an arbitrary way. Speakers REPRODUCE sound, they\'re not supposed to create it. That\'s why MDF is better than plywood for speaker boxes, MDF has uniform density but plywood has natural resonances because of the grain.
Concrete\'s been used for decades as pointed out elsewhere.
It is a rear loaded horn, but not particularly long, and the resonating chamber behind the driver is not well designed (too small, and cylindrical).
I would guess that it rings like a bell with considerable shout at various frequencies.
It has wonderful potential, but this appears to be a poor execution.
I built some concrete speakers based on the \"Frugal Horn\" and they sound tremendous.
The romans had a good handle on acoustics in their concrete architecture..
Resurrected in WWI for use as listening devices prior to radar.
Imagineering is always very important. The use of the word "Technology" for something as ancient and ubiquitous as an Alpenhorn seems inappropriate.