Inflatable Loudspeakers

fm6 sent in an article running at New Scientist talking about new technology that allows Inflatable Loud Speakers. The technology is apparently patented and there's not a lot of technical details, but I have to say the concept amuses me. And I somehow doubt that this technology will ever be used in high fidelity home systems.

Re:patented?

[geekoid]

thats correct, the tech. details are disclosed in an american patent(can't speak for other countries, but its probably the same)
If this is a patented item, as opposed to patent pending, you should be able to go th the US Patent and copyright website and look them up.

Re:Poor roadies?

[fgodfrey]

You obviously haven't tried stacking a medium to large sized PA. I've helped set up stacks of TurboSound speakers 3 high/3 wide + subs (ok, I know, that's not an enormous setup, but it's not for your bedroom either) and while they have wheels, they are quite awkward and heavy. However, I strongly suspect that these speakers will sound pretty bad at high volumes when the bladder starts to vibrate, but hey, I could be wrong. They would certainly look interesting, though :)

Soundtube

[aethera]

I've worked with some SoundTube products before. They were excellent. We used thew in several hanging locations and on the ground in theme parks, so they received a 70 volt distributed PA signal. They played a mix of classical and pop music all day. Sound quality was not excellent, but certainly very good. They were very power efficient and very durable. Bats, Birds, Bees, rain, manure, even lawnmovers attacked these things on a daily basis and they still worked great. One of the nicest outdoor PA speakers I ever worked with.

This Brings New Meaning...

[dbCooper0]

to: Damn - I just Blew a Speaker!

Seriously, I (as a musician with a little experience building cabinets for 18" and smaller drivers), seem to remember that the heavier, the better - at least for Bass Enclosures.

I doubt there is a valid market.

The day has passed since JBL rocked with alnico magnets - you could walk into a music store with a notepad and tape measure, then go back you your garage and cut up some 3/4" or 5/8" particle board, and save big bucks. No patent infringement - I didn't sell 'em - no, really! ;-)

here's the patent info...

[chthonicphage]

Patent Number: WO0154541 (UK)
Publication date: 2001-08-02
Inventor(s): WIENER DAVID
Applicant(s):: SOUNDTUBE ENTERTAINMENT INC (US)

A speaker assembly (100) is provided including a rigid front speaker mounting element (102) defining at least one speaker mounting opening (103), at least one speaker driver (104) coupled to the at least one speaker mounting opening (103) of the speaker mounting element (102), at least one flexible bladder (106) at least partially forming the sides and rear of the enclosure and coupled to the speaker mounting element (102), and a valve (108) coupled to the flexible bladder (106). The flexible bladder (108) has a first wall portion (110) and a second wall portion (112) defining a substantally air-tight interior space (114) therebetween and may take any desired shape when inflated. Together, the speaker mounting element (102) and the bladder (106) form at least one interior chamber (116) at least partially surrounding the speaker driver (104). The valve (108), which provides a substantially air-tight seal when closed, is in fluid communication with the interior space of the flexible bladder (106) and can be used for inflation and deflation of the bladder (106). The bladder (106) is inflatable by providing either pressurized gas or expandable foam within the interior space. Alternatively, the bladder may be formed as a plurality of independently inflatable cells, or may be evacuatably-formed from a material having shape retaining memory properties. After use, the bladder (106) enclosure may be removed from the speaker mounting elemet (102), and deflated for reuse, or disposed of.

Almost Certainly Bullshit

[crucini]

The audio world is crawling with hopeful inventors who don't understand much about sound and electro-accoustics. I've had the privilege of seeing many of these "inventions" first hand. The article failed to address the key issue behind "inflatable speakers": rigidity. In a vented box, which is the most common type of low-frequency and very-low-frequency system, the walls need to be pretty rigid to prevent distortion and energy loss. If these inventors have some way to make a balloon as rigid as 3/4" birch plywood with closely spaced transverse braces, the article doesn't mention it.

The only kinds of speaker enclosure that aren't concerned with rigidity are those that simply enclose rigid horns made of fibreglas, plastic or wood. In these situations, the enclosure merely protects the components from dust, water and damage and does not serve an accoustic funciton. JBL among others has realized this and is making a series of touring speakers which are simply frames of metal tubing with no side walls. Again, inflatable walls would add nothing to such a system.

As for the "beach ball" idea, this can be interpreted in two different ways, due to the lack of detail in the article. If you make a conventional (sealed or vented box) speaker system with spherical form, it will have a sharp resonant peak related to the diameter of the sphere. This peak can be reduced by increasing the absorbent material inside the enclosure, but still reflects a design mistake. A sphere is the worst possible shape for a conventional speaker enclosure. A second application of a sphere is to place it in front of a speaker (possibly a tweeter) creating in effect a radial horn. By careful positioning, two or even three transducers could share one sphere. An inflated beach ball could work for high and even mid frequencies. As the frequency gets lower, however, the need for rigidity of the sphere increases. In general, the sphere should be hard and rigid.

Such a system will never work as well as separate, properly designed horns for the separate transducers. Its only benefit is visual gimmickry and possible cost savings.

Re:Poor roadies?

[kfg]

Most of them, actually. It is, litrally, backbreaking work.

Bear in mind also that speakers often have to be hauled to *hights.* The wheels are useless then. With inflatables you haul could haul 'em up deflated and inflate them in place. Windage wouldn't be a problem, they would be cabled in place, * just as they are now.*

One more factor is space. Did you know that when you buy a box of breakfast cereal the cereal itself only costs you about a quarter? Transporting the BOX takes up much of the rest of the price. A Smaller and lighter transport package means less space and fuel needed just to haul the buggers around.

I have hauled my own PA. It's a pain in the neck, back and elsewhere. I'd love an inflatable rig.

I've also worked on a professional crew, and let me tell you, hauling your own PA around is NOTHING compared to hauling in, setting up, and hauling out, two truckloads of speakers, day, after day, after day.

Come to think of it, I've never known a roadie who DIDN'T complain of back trouble. It's the main reason for retirement.

KFG

Re:Poor roadies?

[Kinetix303]

Yeah, I used to set up raves and concerts with 16 S4 boxes and I thought those were hell.... then moved on to kits with 16 DAS RF-215s and 16 custom Dual JBL 18" in DAS cabinets and I thought those were hell. Then we moved to EAW stacks, which were seemingly endless and seemingly infinitely heavy.

What we decided was that the most efficient way for roadies to lift and setup large kits was just to numb our bodies by quickly slamming back three beers and running to install the gear in that period where we were numb but before we got clumsy.

Worked like a charm.

similar to inflatable guitars!

[guidobot]

There's actually already an inflatable acoustic guitar [chrysalisguitars.com] on the market, I've played it and it works very well. My ex-girlfriend was going to work for the guy making them, but the company is quite poor and couldn't afford to pay her. He was a real nice guy though, and had been trying to make one since 1979. Its based on the physics of an insect wing... there's quite a lot of information about it on the site mentioned above.

Anyways, don't discount the inflatable speakers as things that wouldn't work... these guitars worked really well. I saw them first in the Boston Museum of Fine Arts...

Ellula Sounds Ltd.

[frantzdb]

The article mentions Ellula Sounds Ltd. (not to be confused with EULA). A quick google search gives an article with a picture [lboro.ac.uk]. See also Ellula's corporate page [ellulasounds.co.uk].

--Ben