Which isn't much, but is pretty impressive when it's only in the air because the pilot is managing, from pure muscle strength, to push enough air downwards to levitate himself and the contraption he's sitting in.
Gamera II looks like a total fake in that video, because they didn't get the whole enormous thing in shot, in this indoor testing area. (This helicopter is, of course, not likely to react well to outdoor breezes.)
Here's another test with a wide shot:
Now Gamera II barely looks as if it's getting off the ground at all. This is part of the secret of its success: Even when the helicopter's more than two metres off the ground, the four gigantic rotors are still in deep ground effect, making more lift than they would if they were even half of their 13-metre diameter off the ground.
Among Gamera II's numerous weight-saving cheats is the drive system for the rotors. You'd expect a shaft or belt, but instead there's just a cord wrapped around each rotor's drive wheel like the string around a yo-yo. The cord is wound in by the little wiry dude in the middle cranking away with both hands and feet. When the cord runs out, after only about sixty seconds, the flight is over.
Sixty seconds is enough to win the Sikorsky Prize for human-powered helicopters, though. To win fame and a quarter of a million dollars, your helicopter must have a flight duration of 60 seconds, and reach an altitude of three metres (9.8 feet), which Gamera II has now very nearly achieved.
Thanks to the yo-yo-string drive and various other ingenious tricks, the whole Gamera II weighs 71 pounds - a little more than 32 kilograms.
...famous for its countless appearances on M*A*S*H, had a maximum takeoff weight of 2950 pounds (1340 kilograms).
With its sixty-kilogram little-wiry-dude pilot on board, Gamera II's takeoff weight is 203 pounds - about 92.2 kilograms. So, about 14.5 Gamera IIs to the Bell 47.
(The Bell 47 is also the only helicopter that actually makes that distinctive "chiew-chiew-chiew..." noise that's become the stock sound effect for any movie or TV helicopter being shut down.)
Gamera II, like numerous other human-powered or otherwise-required-to-run-from-not-many-horsepower aircraft, really is huge. The Sikorsky Prize requires the helicopter to remain in a ten-metre (32.8 ft) square during its flight, but I presume that only applies to the middle of the helicopter, since the whole of Gamera II does not even come close to fitting in a ten-metre square. From the outer edge of one rotor disk to the outer edge of the disk opposite it, Gamera II is 105 feet, 32 metres, in diameter.
The Gamera II info-handout PDF has this handy little table in it:
The helicopter's plan-view footprint is indeed similar to that of a 737, bigger than the US military's biggest helicopter, and way bigger than a Black Hawk.
Forget that, though. This thing's even bigger than the sadly unpopular Fairy Rotodyne:
(The Rotodyne was a compound gyroplane that drove its rotor for takeoff and landing, but cruised with the rotor spinning freely, like an autogyro. The rotor was also driven by tip-jets, not a shaft, so the Rotodyne didn't need a tail rotor. The deafening noise of the tip-jets on takeoff and landing is usually cited as a major factor in the commercial failure of the Rotodyne.)
(I just finished watching the two-part documentary Jet! When Britain Ruled the Skies; the Rotodyne scores a mention toward the end. My favourite part of Jet! was when the narrator, who has only played the Queen once, said "Not only did Capital Airlines fly the Viscount, but they also admired its virtues, in that warming, homespun way that only Americans can fake.")
The Rotodyne's rotor had a diameter of ninety feet - 27.4 metres. That's 15 feet (4.6 metres) smaller than the Gamera II's diagonal.
If you want really big helicopters, you need to go to the Soviets.
...(probably because all the service manual says is "oil main rotor bearing every three years"). The Hind's rotor diameter is a mere 17.3 metres, though. Four-thirds as big as a single Gamera II rotor, but only 54% of the Gamera II's total maximum diameter.
...of which only two prototypes were built. Two slightly overlapping rotors (out of sync with each other, of course), each of which was 35 metres (115 feet) across.
OK, that one wins.
(For comparison, the Boeing Chinook, with its less-bizarre tandem rotor design, only has 18-metre, 59-foot, rotors.)
These comparisons are of course ridiculous; it's like comparing a dandelion seed head with different sizes of musket ball. I only did it to have an excuse to post a bunch of giant-helicopter videos.
(Some Wikipedia-helicopter-data-table writer must have enjoyed filling in the names of the three "powerplants" the Gamera II's used, and its cruise speed of "0 kn; 0 km/h (0 mph)".)
Anybody who runs a blog with more than one post a year will receive unsolicited offers of "content". I get them all the time.
It's a distinct category of spam. They offer you a "free" blog-post worth of text, and often also a small amount of money, in return for you publishing said text, a few words in which link to some Web site the contributor specifies.
This one's a little more interesting than most.
From: Robert Lobitz <r.lobitz@kasacapitalmarketing.com>
To: rutterd@OPTUSNET.COM.AU
[This is not a good sign. That e-mail address is the one on my dansdata.com domain registration; it's not my actual Dan's Data contact address, dan@dansdata.com, that anybody who visited the actual site could find. Mail to domain-registration addresses is sort of like when a phone caller starts out by asking if he's speaking to Mr or Mrs surname-of-partner-to-whom-you-are-not-married.]
I would like to start by saying that I was thrilled to find dansdata.com - it's not everyday I find a website of this caliber!
[Whenever someone cold-e-mails me saying something like this, I Google what they just said and, usually, find a few thousand copies of the same text, making clear that they not only actually do find a site "of this caliber" every day, but may find one approximately every minute. This time, though, there were only a couple of hits. So, good so far!]
I am interested in having one of my unique and interesting to read articles
[Yeah! Sell it, baby!]
published on dansdata.com. In return, all I ask for is that you let me include a link to my site HIDXenonHeadlights.com from within the article --- I would be willing to offer a one-time monetary contribution as well. Please let me know if this sounds like something you'd be interested in.
Cheers,
Robert
Public Relations
KASA Capital
909-444-5100
As I write this, the first hit in a Google search for this gentleman's alleged name is an article called "A Brave New Reality: Changing the Bird Cages of the World"
I cannot, in all honesty, say that that article is truly "interesting to read". It's more like "first-year university student trying to make it to the specified page count when he didn't do the reading, has a killer hangover, and has to turn in the paper in one hour".
The "Brave New Reality" article is also almost entirely free of any actual information. The world must change, and the world changes, and we should change the world, apparently. But it does at least seem to be pretty close to "unique", and not sprayed all over umpteen other blogs that also accepted the "one-time monetary contribution".
(To see if a given chunk of text is a "proper" article and not a sort of journalistic copypasta, take a distinctive string from the article - in this case, let's use the rather odd "Among my pursuits and businesses are the caring of birds as protected pets" - and search for that. [Spelling errors make these searches a lot easier.] Your typical spam-article, scam e-mail or bullshit Wikipedia reprintsold on eBay will have a zillion hits. As I write this, though, the "Brave New Reality" article is only published, as opposed to discussed, on two sites, culturechange.org and evolvingsustainability.com. The latter site is currently down, and may belong to the same guy as the first site anyway.)
The real purpose of "Brave New Reality" is, of course, not to actually inform or entertain. It's to link to a site and get it some Google-juice. In this case, that site is BirdCages.net. Hence the rather stretched metaphor.
Hit two for Robert Lobitz's name is "Child-proofing the Bedroom". Again, it's plainly been written by someone who doesn't have much writing skill, and it doesn't really say very much, but it is unique to the site it's on. And it gets its link in, too, this time to BunkBeds.net, which unsurprisingly looks very much like BirdCages.net.
Those two sites are both subtitled "A KASA Store". KASA Capital are strangely reticent about how many of these sites there are in their "diverse network of e-commerce entities", but I think it's safe to say there are a lot of them. They seem to be kosher online shops, too; no discount Viagra or fake watches.
I wanted to see just how many of these sites there are. It took me a moment to find something to search for that was distinctive to sites following the BirdCages.net/BunkBeds.net template, but I managed it by searching for a couple of strings of the hours their customer-service phone line is open.
Motorcycle fairings, medical scrubs, baby changing stations, martial arts supplies, silk flowers, caviar, boxing bags, radio-controlled planes, bike carriers, easels... if I'm counting right, there are 20 KASA sites found by the above search. If they've got more than one template, they could have a lot more than twenty sites.
I think it's safe to say that KASA are not experts on train horns, bar stools, poker chips, fish tanks and so on. I would, in fact, bet good money that they're just drop-shippers, who never even see the products they sell. Buy at wholesale, sell at retail, send goods straight from the wholesaler to the customer, spend the rest of your day on the golf course.
(The contact-hours search didn't find HIDXenonHeadlights.com, the site the article Robert was offering me would have to link to, because HIDXenonHeadlights.com has a different template. Searching for a string from that site's contact page found a few more KASA sites.)
So as far as KASA's actual retail business goes, they may not be the best place to buy any of the numerous things they sell, but I see no reason to suppose they'll take your money and run.
This still doesn't make it a good idea for blog-owners to take link-buyers like KASA up on their offers, though.
For a start, all you get, besides however much money they offer, is this worthless fluff-content that only exists to link to some site that frequently has nothing to do with the site on which the fluff appears.
More importantly, if Google notice you're engaging in link-buying schemes - or have been so deeply idiotic as to allow links to link-buyers' sites to appear on your site for free - they'll punish you by reducing your site's PageRank, as well as that of the link-buyers themselves. Serious offenders can be erased from Google altogether until they perform suitable penance.
So I'm sorry, Robert, but unless the "one-time monetary contribution" is in excess of a hundred thousand dollars, I'm afraid I'll have to turn down your offer.
And congratulations: You're in a pretty lousy business, but you could be worse!
A few years ago, when these branded collections of spherical (and now also cubic) magnets were first gaining popularity, one of the sellers of such things noticed I'd written this, this, and this (and possibly they also noticed this), or just that I'm pretty high in the results for a Google search for rare-earth magnets. They offered to send me some of their "jewellery magnets", from which you can make bracelets and rings and uncomfortable earrings and so on, for review.
I said it looked as if the more complex shapes would be fiendishly difficult to create without all the magnets clicking together into a blob all the time, and asked if this was a problem.
They didn't reply. Or send me a free infuriating blob of magnets.
(Years ago, Mark picked up my Amazing Magnets ball and squished it into a coagulated impossible lump. I left it that way. It took Alan, whose lot in life it is to protect the world from the entropic influence of people like me and Mark, ages to reconstruct it.)
That constitutes the entirety of my professional involvement in the little-toy-magnets world. Perhaps I was wrong; it's demonstrably possible to make all sorts of nifty things with them:
Toy magnets like these are now banned, in the process of being banned, or at least temporarily withdrawn from sale, in various jurisdictions both here in Australia and elsewhere.
All this excitement has happened because rare-earth magnets are dangerous to swallow.
They're not a poisoning hazard. An alternative name for the ceramic these magnets are made from is "NIB", for neodymium, iron and boron, and those elements are not particularly toxic to mammals individually or in combination. (Calling these things "neodymium magnets" is actually pushing it a bit; it's the neodymium in the formula that allows it to be magnetised so strongly, but the molecule is mostly iron, Nd2Fe14B.) The fragile black ceramic of the magnets themseves is almost always covered with a protective material, usually a plating of shiny nickel, but that's pretty harmless, too.
Swallowing one or more rare-earth magnets in one go is unlikely to do any harm at all. They'll just click together in your mouth or stomach, and probably pass through your gut without complications; even the block-shaped ones have rounded corners.
But if you swallow one or more magnets, then wait for them to move down your gut a bit, then swallow another magnet or three, the separate magnets or masses thereof can stick together with some of your tissue in between. This is likely to be Bad News.
(You can probably do something similar if you inhale one magnet after another, too. The above-linked medical literature also notes that a kid who's swallowed only one rare-earth magnet, and then goes in for magnetic resonance imaging, can find himself in a world of pain.)
These problems are not actually a new thing. As the New York Times points out, previous rare-earth-magnet construction toys have also been withdrawn, for the same reason.
...which is based around plastic pieces with small rare-earth magnets on their ends and corners. And Geomag wasn't an original idea, either; people had been making sculptures out of rare-earth magnets and steel balls for years (q.v. that Amazing Magnets ball, which I reviewed in 2002).
...came out a couple of years before Geomag. It has much longer rods, and larger magnets recessed into the ends of the rods for a less wobbly connection. I bought a couple of sets years ago, and they're still on saletoday, though perhaps not for much longer.
Geomag was the first really popular rare-earth-magnet construction toy, though, and it spawned umpteen cut-price competitors.
You can lever or chew the magnets out of the ends of Geomag-type components (or, for advanced experimenters...
...dissolve the rods in acetone), and the magnets will just fall out of some of the really cheap and nasty Geomag knockoffs. And a child that eats one, waits a while and then eats another, may end up grievously injured.
"Magnetix" was the biggest Geomag knockoff brand and far from the worst-made, and it was withdrawn from sale in the USA after loose magnets killed one kid and put a few others in surgery.
Over the same period of time, bicycles killed, maimed and paralysed far, far more children, of course. But that doesn't make it OK to sell toys with small parts that fall off, even if those small parts don't have the ability to give you bowel ischemia via quantum physics.
The people who sell little round-or-square magnets under brands like...
...Buckyballs or Zen Magnets don't contest any of this. They've also previously cooperated with regulatory bodies by improving their safety warnings and complying with the usual bureaucratic labelling-law friction, like when Buckyballs said their toy magnets were suitable for children aged 13 and up, when existing local law said they only actually meet the requirements for 14 and up.
...a "Save Our Balls!" campaign, and a petition, and so on.
Their argument is pretty straightforward: There are many things which, when left unattended, and found and eaten or otherwise interacted with by a toddler, can gravely harm said toddler. Few of these things are banned, because even if humans abandoned civilisation and returned to the trees, there would still be rocks and sharp sticks all over the place.
The CSPC's purpose is to "protect the public from unreasonable risks of injury or death". Their full complaint (PDF here) contends that these magnets do constitute such an unreasonable risk, because no warning on the box or in the instructions can prevent these little magnets from being left stuck to the fridge or on the floor or in some other place where small kids can find them. The CSPC also contends that older children, if they do things like simulating mouth and tongue piercings by putting a magnet on each side, can swallow or inhale the magnets and end up very ill. This has actually happened at least once. (Given the popularity of tongue studs and of these magnet toys, I bet older children have swallowed one or more magnets quite a lot of times. It's only likely to be a problem if they wait a while and do it again.)
I think the most important part of the CSPC complaint, though, and the part which raises it above mere Think OfThe Children busybody nonsense, is that consumers demonstrably do not recognise the risk posed by toy-magnet products.
The CSPC are not complaining about knives, and saucepans full of boiling water, and automobiles, all of which harm and kill far more children per year than little magnets do, because it is generally recognised that children need to be protected from these things. Mostpeople with toddlers, or even without, would not leave a straight razor taped to the fridge two feet off the ground.
But people haven't gotten a similar message about little magnets.
And it's not a theoretical problem; kids keep eating the damn things.
The CSPC complaint mentions only Buckyball- and Buckycube-branded magnets, but if it's upheld, I think you can can reasonably expect all such magnets to be banned in the USA.
I'm not certain, though. It could just end up banning such magnets when they're sold as novelties or toys.
This seems to be the way it's working out here in Australia. The Western Australian ban does not apply to "magnets used for industrial or scientific purposes"; similar exceptions are made in a 2010 Tasmanian interim ban (PDF here), and in the recent New South Wales interim ban (PDF here).
I'm actually quite heartened by the NSW ban, because it specifically says it only covers magnets "that are intended or marketed by the manufacturer primarily as a manipulative or construction desk toy or as jewellery".
This is still bad news for sellers of brightly-coloured marked-up magnet packs, and still means many ordinary consumers will miss out on being able to pay the premium to buy such items in ordinary consumer outlets, and probably won't be able to find them anywhere else.
But this ban says nothing about people selling un-marked-up magnets, without any statements about their purpose, for rather better prices on eBay and elsewhere.
Spherical magnets seem to be a little thin on the ground on eBay right now. Craft yourself a round-magnet-finding search string and all you'll see are disks and cylinders. I wouldn't be at all surprised if many sellers (overwhelmingly in China, which is where I think all cheap NIB magnets are made) decided to stop listing spherical magnets for a while, in case their products all get seized by Customs wherever they send them, and they then get lots of negative feedback.
If you cease to discriminate by shape, though, it's not hard to find inexpensive "Buckycube"-type cubic magnets.
"Buckycubes" are 4mm NIB cubes in a selection of colours. The cheapest no-name eBay cubes are all plated with silvery nickel, and may have thinner plating (or may not), but very small NIB magnets like these are generally hard-wearing; even the tiny contact points on spherical ones don't wear out that fast. And if they're way cheaper you probably won't care if the nickel flakes off a couple of them.
A 216-piece pack of Buckycubes will set you back $US39.95 + $US5.95 for shipping; 21.25 US cents per cube. To be fair, it'll probably cost you a bit less, since the Buckyballs people are for some reason currently having something of a fire sale, with coupon codes and such. 20% off your whole order seems to be easy to get; if that applies to shipping as well as the item price, then you'll be paying 18.4 cents per cube.
Restrict your eBay search to 4mm cubes, and as I write this you'll find the cheapest 216-piece pack for $US26.39 delivered; that's 12.2 cents per magnet. (Make sure you do a "world" search; local-currency prices in Australia, at least, are a bit higher. It seems that even China can't believe how crappy the US dollar is these days.)
This seems to be about the floor price. If you want a thousand-piece pack, it's $US119.99 delivered, a molecule less than 12 US cents per magnet.
UPDATE: I just noticed that well-known online cheapie-shop DealExtreme is shamelessly selling a set of 216 golden 3mm sphere magnets for $US15.40 delivered to anywhere, 216 5mm black spheres for $US17.10 delivered, and 125 4mm silver cubes for $US16 delivered. These are excellent prices to start with, and there are bulk discounts if you want to buy three or more units. Just don't try to re-sell them, if you live somewhere with these anti-toy-magnet laws!
UPDATE 2: More DealExtreme tiny-magnet sets. If you're a real penny-pincher they'll sell you a hundred minuscule 3-by-1mm discs for only $US4.10, and they have a nicely-packaged 216-3mm-sphere pack for $US15.60. 216 "silver white" 5mm spheres (which really do look silvery rather than just polished-steel-ish) are $US20.30, as are 216 golden 5mm spheres. 216 silver 4mm cubes will set you back $US18.70; 216 5mm cubes in the same finish are $US20.80.
Oh, and here are 216 red 5mm spheres for $US17 delivered!
(And then there's this kit, which only gives you 27 spheres and 36 long rods for $US15.90. But it comes in a nice little metal box! And here are yetmore cubic ones in nice little tins. And here's a balls-and-bars set at DealExtreme that actually comes in Buckyballs packaging, which would normally mean it's a knockoff. Now, though, it may be the real thing, being sold where the product ban cannot reach.)
Again, these prices are all excellent, and you can get the usual bulk discounts; if you decided to buy a thousand of the super-cheap tiny discs, for instance, you'd pay $US33.90 delivered for the lot - three point four cents per magnet!
When I started writing this piece, I was all fired up to mention yet again that Kinder Surprise chocolate eggs with a toy inside are banned in the USA, and they're not banned in most other places, and the confectionery aisles of Australian supermarkets are not, so far as I have been able to determine, littered with the corpses of asphyxiated children, and presumably that's because all Australian shelf-stackers know how to administer the Heimlich maneuver. I also contemplated using the term "natural selection", with regard to children over the age of ten who eat their toys.
And as I've written before, I'm not crazy about preventing grown-ups from having things that could hurt children, or other adults, if used irresponsibly. Things keep being banned if they're possibly hazardous and, in the opinion of busybodies, more fun than they are useful. This is, to use the technical term, bullshit; it's the sort of Puritan worldview that bans recreational drugs for no reason other than that they are recreational drugs.
Most sane people accept, however, that it is difficult to make a case for private ownership of land mines in the civilised world.
Or, to pick a more realistic scenario, it is fair to prohibit the construction of booby traps on your own private land to catch trespassers, because even if it is your private land, you're living in a society here, and bear-trapping firemen, punji-staking tourists who wish to ask for directions, or SM-70-ing anyone who investigates the smell after you die in your house, has been decided by the rest of us to be unacceptable.
Less theatrically again, this is why the civilised world generally requires people building and maintaining structures to do so to something approaching local code standards, because you're not the only person who's going to have to deal with the place, even if nobody else busts in there until after you've died. If you want to have deathtrap electrical wiring, giant piles of fermenting garbage and guard dogs driven insane by mistreatment, get the hell out of the First World, because we've decided we won't put up with that. There's a limit to the risk to others that you're allowed to create in the name of individualism.
And so, after yet another reduction of the drama involved, we get to little shiny toy magnets.
On the one hand, they're fun, and the number of serious medical incidents they've caused is trivially small compared with those caused by skateboards, netball or hiking.
But on the other hand, they have been demonstrated to pose a real hazard, and there's no good way to mitigate it. No amount of "keep away from ALL children" warnings will make these small shiny lose-able objects actually inaccessible or unattractive to small children, and people don't seem to take the warnings seriously anyway. And even if you've no kids and no intention to have them, the little bastards are still likely to find their way into your house at some point.
And the danger isn't just of cuts and bruises. A perforated bowel will very probably kill you if you don't get serious medical treatment, whether you're four or forty.
One way to mitigate the danger of products and activities is to require licensing or other legal paperwork before someone can buy or do whatever it is. But this is for guns and cars and SCUBA and skydiving; it's ridiculous for executive-toy novelties.
We live in a world of imperfect solutions, and upon reflection, I think bans on small magnetic novelties aren't even the least perfect solution I've seen today. Especially if it's not a Ban On All Magnets.
As long as you can still buy 10,000 round NIB magnets with the same specs as the ones sold under special brand names on eBay, or wherever, or similarly buy tons of even cheaper disc magnets for the thousand and one things they turn out to be useful for, then I don't count destruction of the market for marked-up novelty-shop (or evenworse) versions of the same things to be a great injustice.
I accept that the current magnet bans are much more likely to lead to truly onerous and irrational magnet bans than, say, the acceptance of gay marriage is to lead to people marrying farm animals. If and when someone tries to ban strong magnets in general, even huge ones that pose a serious danger to grown-ups, I will stand up and be counted in opposition.
But even as a quite serious appreciator of weird and wonderful toys and gizmoes, I see no strong grounds for complaint in bans on little magnets sold as toys.
If you're looking for some reading matter to ease you into loudspeaker design and construction, do not buy Vance Dickason's famous, though now out of print, Loudspeaker Design Cookbook. Even getting a pirated PDF of it is not a great idea. This is because the Design Cookbook is for people who already know what they're doing - its subtitle is "Everything you Need to Become a Better Speaker Designer", emphasis mine. You're going to have to learn about Thiele/Small parameters and some other technical stuff at some point if you're building most kinds of multi-driver and ported loudspeaker, but there are several kinds of speaker you can build without doing anything beyond basic arithmetic.
There are a ton of books about speaker design, most of which I've never read, so maybe I'm about to suggest you go in a non-optimal direction. But the best book I have read on the subject is V.A. Capel's An Introduction to Loudspeakers and Enclosure Design, which is also out of print but can still be had cheaply on Amazon and on eBay (there are local Australian and UK sellers!UK sellers!).
An Introduction to Loudspeakers and Enclosure Design does what it says on the tin, and includes detailed instructions for building one of those single-cheap-driver transmission-line speakers I'm so keen on. If you build it according to the instructions you'll end up with a folded transmission line with ceramic-tile reflectors on the corners; I'm pretty sure just making the reflectors out of wood wouldn't significantly hurt performance.
There's a whole subsection of the audiophile world - both the empirical and the woo-woo side - devoted to single-driver speakers, and such a speaker is a really good option for your first speaker project.
A solidly constructed box with a single cheap driver can sound remarkably good, especially if the speakers are close to the listener, even though the responseplot reports high treble and low bass are missing, presumed dead, and the midrange response looks like a Worms battlefield.
Loony-audiophile supply houses stand ready to relieve you of extraordinary amounts of money for Fostex or Tannoy drivers...
(Image source: Flickr user drosen7900. More about these speakers here.)
...but now that few people use CRT monitors and TVs, you can build your own computer or hi-fi/home-theatre speakers without even bothering to use magnetically shielded drivers. Any dirt-cheap paper-cone wideranges, or multi-driver round or oval car speakers (which are not strictly speaking single drivers, but can sound good just the same) will do.
And for your first project, all you need is a sealed box, the bigger the better, with one hole in the front that roughly fits a single driver. You will probably need to be able to solder, but not a lot of work is involved, and what work you do have to do can be quite sloppy and still give a perfectly functional result. (Think of it as the Roman Army knife of loudspeakers!)
Oh, and on the subject of very heavy speaker cabinets: What do you do if you've already got some speakers, but you want their cabinets to be less resonant?
A commenter on yesterday's post about glass-fibre speaker-box lagging lamented that he can't get loudspeaker kits in the States.
He is wrong. There are definitely speaker-kit sellers in the States. Probably quite a few of them, given the much larger market. (Australian population: 23 million. US population: 314 million.)
I think the biggest name in US speaker kits (do feel free to correct me in the comments) is Parts Express, mostly under their in-house "Dayton" brand. There was a Dayton driver...
Parts Express sell everything you need to make speakers of your own design, and have a reasonable selection of kits, too. Their speaker-kit listing is here; prices are quite good, especially given that most of the kits have enclosures that are veneered or otherwise nicely finished.
This super-cheap Parts Express kit comes with only bare plywood boxes, but it's two little 2-way speakers for $US128 with free US delivery! For some reason the kit lacks binding posts and wire, but you can get those for a few bucks more; if you're really pinching pennies, buy those parts on eBay from China.
(Oddly, absolutely nobody seems to sell speaker kits on eBay. I wonder if that's because of the awkwardness of shipping all that wood.)
Note that these little speakers aren't really "bookshelf" speakers, because they have a port on the back, and if you plug the port by pushing it up against a wall, your bass will go away. You certainly can put them on a bookshelf, but you can't push them all the way in like a book.
...and regrettably also out of stock, but how can you not want them!?
Back here in Australia, the inventively named "The Loud Speaker Kit", makers of all the kit speakers I've reviewed, is now out of business. I'm not an authority on other Australian speaker-kit places, but I know of a few.
Peninsula Home Theatre have some rather expensive options (their prices are per speaker, not per pair...), but the drivers are high-quality and the boxes are very nicely finished.
Danish Sound Technology have kits, but you have to contact them for prices, which is not a good sign.
The Fountek "Signature Series" kits look good for the money, though.
ER Audio has electrostatic-speaker kits, which are all very expensive, but that's because electrostatic loudspeakers are awesome. (They're hideously incompatible with cats and small children, though.)
VAF Research sell kit versions of at least some of their speakers, too, but they're very high-end so their kits cost thousands as well.
At one time or another I think all of the Australian chain electronics stores - Altronics, Dick Smith, Jaycar and possibly even Tandy (Radio Shack in the States, amalgamated with Dick Smith now in Australia) - have offered speaker kits. At the moment I think only Jaycar have them, and they've only got one.
...some very nice European-driver loudspeakers for $AU698 all up, which is quite good value.
You could save a little by only buying the electronics and building your own cabinets. Many "speaker kit" dealers work this way - they sell "short form" kits, giving you everything but the boxes. In Australia, people who sell these kinds of kits include Soundlabs Group and Stones Sound Studio, the latter dealer continuing the proud association between... untidy... Web-site design and audiophilewoo-woo. (They also sell the Fountek kits mentioned above.)
Making your own enclosures isn't actually all that hard, by the way; I did it when I was a teenager. If you're a DIYer without a table saw, you just go to a place that sells wood-sheet products and get them to cut some MDF to size for you. Note that they will probably only do cuts all the way across the sheet (or what remains of the sheet after previous cuts), so it can be a bit of a puzzle to get all the parts you want out of the minimum number of sheets. This lets you have unusual finishes on your speakers, though; any material you can use for a kitchen counter, for instance, you can use for a speaker.
Anyway, you get the panels made, then assemble the boxes at home with simple screws 'n' glue and ugly butt joints (proper woodworkers of course use mitre joints). You can jigsaw the holes for the drivers; it doesn't matter if the holes aren't perfectly round, because the driver surround will cover them.
(When I was about 15, I cut my own box panels freehand with a jigsaw from a sheet of super-cheap particle board, and then plugged the gaps where the wood didn't quite touch with Blu-Tack!)
Taking the further step of building your own speakers from scratch isn't that hard, either, especially if you build simple sealed boxes. Doing it entirely yourself is also the only way to get some unusual speaker designs, like corner-loaded horns and transmission lines, at an affordable price.
Transmission lines are one of my favourite loudspeaker types. You make a tall hollow square wooden tube, or reduce the size by folding the tube and putting periscope-type sound-reflecting angled pieces on the corners. The drivers go at the top in the front, there's a port at the bottom at the back, with lagging material all the way down the tube so very little sound actually makes it out of the back. Even if the driver you use is a paper-cone widerange from a junkyard car, the result will often be quite startlingly good, even though the frequency-response plot will look dreadful.
There's no good way to get low bass out of this design without making it really big, though - I once made some folded transmission lines with eight-inch whizzer-cone wideranges in them, and they still didn't have really low bass, but were serious pieces of furniture. So if that matters to you and you don't want the speakers to dominate the room a bit, you'll need a subwoofer as well.
Building your own cabinets also lets you massively over-build the cabinets, for near-zero panel resonance. The easiest way is to use super-thick wood and many braces inside, but you can also make a double-walled design filled with sand, cement or even lead shot, or line the panels with lead sheet. Many super-expensive speakers have cabinets like this, but retailers hate them; do-it-yourself lets you have super-cabinets with affordably-priced drivers in them.
I'm sure some readers know of other speaker-kit outfits; I only mentioned Parts Express in the States, but I'm sure there are more options there and in other countries. I invite people living elsewhere to comment.
And heck, we don't even have to be talking about only kit speakers. Do tell if you know of pre-built speakers that offer similar value for money, like those white-van speakers sold for fair prices on eBay I wrote about a while ago.
...and was very impressed with the information provided.
Is it true that glass fibre batts in speakers can cause mesothelioma? I noticed you linked to the Wikipedia mesothelioma page when discussing polyester and glass fibre batts with the word "carcinogenic".
Bailey
A ported speaker with glass-fibre wadding inside (it's there to dampen internal resonances) will spit little bits of fibreglass out of its ports in normal use. The cancer risk from these is essentially nil, mainly because the amount of glass emitted is very small. But even larger glass-fibre exposures are generally less dangerous than asbestos exposure, and there's some debate about why this is.
Fibreglass and asbestos are mechanically, and somewhat chemically, similar. Glass-fibre, like window glass, is about three-quarters silicon dioxide (quartz), with the rest being additives, chiefly oxides of light metals, to reduce the glass's melting point and improve its strength and/or chemical properties. All forms of asbestos are essentially silicate minerals too, but with different elements mixed in with the silicon and oxygen.
The most common form of asbestos is the white "serpentine" kind, which is magnesium silicate. Blue and brown "amphibole" asbestos are closer to window-glass, being complicated sodium, magnesium and iron silicate minerals.
Asbestos is so particularly nasty (and useful) because its fibres can be very, very fine, routinely below twenty micrometres (or microns) in diameter, and even down to small fractions of a micrometre, versus around 100 micrometres for a human hair. These ultra-fine fibres are too small to even see, and bits of them can float around in the air waiting to be inhaled. This is why they tent whole buildings and put workers in moon-suits to do asbestos abatement; building materials that contain asbestos can be safe to be near, but as soon as you start busting those materials up, they can produce dangerous and invisible dust.
Fibreglass, also known as glass wool, is made in a similar way to fairy floss ("cotton candy", in the USA); extrusion of the molten material through tiny nozzles. The nozzle size determines the thickness of the filaments, so glass fibres can quite easily be made down to single-digit-micron thickness. As is the case for many other "whisker" materials, most of the desirable physical qualities of the fibres increase as the thickness drops. (This is explored in some detail in J.E. Gordon's classic "The New Science of Strong Materials, or Why You Don't Fall through the Floor", a book that I may not have mentioned on this site for as much as eight or nine minutes.)
This electron micrograph of dust from the wreckage of the World Trade Center (via the USGS) shows a thin glass fibre and a bundle of much thinner asbestos fibres.
(Nobody performed full asbestos abatement on the WTC towers while they were standing, because it would have been very expensive, the asbestos was largely safely bound up in building materials, and nobody expected the buildings to fall down.)
Glass fibres down in the single-digit-micron diameter range are a cancer risk, like asbestos, but glass fibre in general seems to be rather less carcinogenic than asbestos fibres of similar dimensions. Nobody's exactly sure why. Glass fibres don't seem to get stuck in the lungs like asbestos fibres do; this could be purely because of the size difference, or because they don't have the same rough, almost barbed sides...
...as many asbestos fibres (that's another USGS picture).
Glass is also slightly soluble in water, and - it is theorised - fibres in the lungs can thus be slowly eliminated via blood or sputum. For macroscopic objects the water-solubility of glass is essentially zero; you can run water through a glass tube in a laboratory for years with no visible change, and you don't need to worry about rain wearing through your windows. But the thinner the fibres, the greater will be the surface area of those fibres relative to their volume. So even extremely slight solubility can, the theory goes, get rid of the fibres usefully quickly.
It's important to realise that we're not just talking about cancer, here. Most people with asbestos-related lung disease don't have mesothelioma; they've got "asbestosis", a non-cancerous inflammatory disease which can, nonetheless, very effectively destroy your quality of life and in extreme cases kill you. Again, it's the super-fine fibres of asbestos that make it particularly nasty here, but you can get similar syndromes by inhaling various other particulate substances that get stuck in your lungs, like coal dust, and also little bits of fibreglass.
Realistically, even someone who stuffs fibreglass into speaker boxes for a living, without so much as a face mask, isn't at a huge risk of lung disease - cancer, or "just" an asbestosis-like condition. Usually it's people like surfboard manufacturers or insulation installers who get sick, and then only if they don't use a respirator while they're sanding boards or stuffing insulation batts into unventilated roof or floor cavities.
So if you've got ported speakers with fibreglass in them, don't worry about it. Even if you open the speakers up to replace a blown crossover or something, you're in no real danger. (And if you've got un-ported, sealed "infinite baffle" speakers, there is of course even less risk.)
...as the normal low-cost anti-resonance speaker-lagging material...
...some time ago, but I think the change was mainly because these fibres are easier to cut and place, and not a prickly skin irritant, rather than for health reasons.
Incidentally, white asbestos and talc, as in talcum powder and...
..."French chalk", are chemically the same, both magnesium silicate. Asbestos can metamorphose into talc, though I'm not sure if talc can go the other way. In any case, industrial-grade talc can be expected to contain some asbestos-like filaments.
This fact caused a certain amount of panic among people who've applied talcum powder liberally to their baby, or discovered that standard children's wax crayons contained a small amount of talc, which in turn did or did not contain - depending on who you asked - a tiny amount of actual identifiable asbestos.
(Some people went so far as to allege that because they're chemically the same, talcum powder is asbestos. By this logic, it should be easy to drive nails with a Brillo pad. But have no fear, highly independent thinkers stand ready to help you remove asbestos from your spine with magnets!)
In response to this, more than a decade ago the big-brand crayon formulations were changed to contain no talc. How crayon-talc was supposed to get into kids' lungs in the first place, I'm not sure. Embedding asbestos in wax strikes me as an excellent way of rendering the stuff harmless, even when kids stick crayons up their noses. Perhaps some asbestos could lodge in the digestive tract if they ate it, but I think the normal regeneration of the gut lining would carry it away. Unless you actually lit a crayon fire, I doubt any significant exposure was even theoretically possible.
The asbestos-in-talcum-powder scare was more rational, because people unquestionably do inhale some talcum powder when they use the product in normal everyday ways. There's a difference between bulk industrial talc and the super-fine stuff used for talcum powder, though. Major talcum-powder companies hotly protested that there was no asbestos in their talc at all.
It's rational to take at least some care to prevent you or your baby from inhaling talcum powder, because, as discussed above, inhaling fine insoluble powders in general is a bad idea. But there doesn't seem to be any serious reason to boycott the product entirely.
(There's also a popular belief that laser-printer or photocopier toner is deadly poisonous if inhaled. Actually, toner is just yet another insoluble fine powder. So, once again, you should avoid inhaling it if you can, and wear an appropriate mask if you have chronic exposure to it. But there's no need to panic if you snort a little of the stuff by accident.)
I wondered whether yesterday's rant might win me some angry accusations of being anti-American. It hasn't really, yet. But do allow me to clarify just the same.
Which, clearly, is far from being what all Americans believe...
...but which, like certain other works, does exemplify what many of us foreigners find objectionable about the USA.
More specifically, I have a problem with many of the USA's domestic and foreign policies and actions, because they do a lot of harm to both American people and the rest of the world. These policies do not, of course, all grow out of the above-depicted conviction that the USA really is God's own country. A stronger factor is that the USA is powerful enough to do terrible things outside its borders, and the USA's government/corporate rulers are powerful enough to do terrible things inside its borders, which I'm sure any number of other countries would also do, given the chance.
The most important part of my objection, which is particularly brought to mind by that incredibly jingoistic movie, is based around the horrifying fact that an awful lot of the world's leaders - certainly not just the American ones - are clearly guilty of war crimes, most notably crimes against peace. Many of these leaders have gone on national television to boast of their war-making achievements, after previously going on TV to persuade the populace to support a new war in the time-honoured fashion.
Major war crimes, of which crimes against peace are the very worst, are the only offenses which I think actually should carry the death penalty. Preferably with those sentencing the offender to death putting their own lives on the line - if the offender turns out to have been innocent, the judge and/or jury are executed. (This'd pretty much solve the USA's own death-penalty problems, don't you think?)
Anybody who drapes a patriotic flag over war crimes is an enemy of humanity, and the higher you go in various nations' governments, the more this happens, and the less forgivably. Random yahoos who believe God sent George W. Bush are one thing; if you honestly think Saddam was responsible for 9/11 then you sadden me, but I don't think you should be punished for being ignorant and/or gullible. But people like Dick Cheney, Henry Kissinger and Robert McNamara knew exactly what they were doing.
(It has long been my opinion that we should offer John Howard lifetime imprisonment instead of execution in exchange for his testimony against Cheney and Bush. I also find it difficult to argue against just assassinating a bunch of these guys. Everybody knows they're never going to see the inside of a courtroom, and they made speeches and published books proudly declaring their guilt, so I think it's pretty cut and dried, don't you?)
Movies about tankcrews and fighter pilots and Special Forces badasses can be horrifying and entertaining, both at the same time in the very best examples. But I find it unnerving that the USA now gets in wars so interminable that books, movies and video games about those wars exist while the war's still going on. We've now given up on waiting a few years after the end of the war before turning it into entertainment products, for the sake of common human decency. Nowadays the wars are on abstractconcepts or thingseverybodylikes, and there's no particular prospect of matters improving until all of the USA's arable land blows away into the ocean and the US dollar falls to about one jiao.
On a marginally happier note, here are some more good-war-movie recommendations, all about events that happened a decorously long time ago.
Clint Eastwood's siblingfilmsFlags of Our Fathers and Letters from Iwo Jima are extraordinary. The second is a brutal war movie about the Japanese soldiers trying to hold Iwo Jima in 1945; the first is about the American side of the story, with a heavy emphasis on the patriotic-bullshit factory a few American Iwo Jima heroes find themselves working in.
, 
about speaker design, most of which I've never read, so maybe I'm about to suggest you go in a non-optimal direction. But the best book I have read on the subject is V.A. Capel's An Introduction to Loudspeakers and Enclosure Design, which is also out of print but can still be had cheaply 
and 
