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I came to the conclusion a good while ago that advice from audiophiles or home theater enthusiasts (I count myself among these, even chased the THX dragon for a while) is largely religious in nature. After many years and much discovery I have come up with a solution that absolutely works for everyone. Throw away the science. A true audiophile will balk at this because no one wants to admit their time might have been wasted. We all have basically the same auditory senses in various states of disrepair. That's why this works for everyone and there is absolutely no argument against it: 1) position your speaker one way. 2) Listen. 3) Position it another way. 4) Listen. 5) Place the speaker in the position that sounded better. Repeat as necessary.
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Subwoofers, especially larger ones like 10", 12" or 15" produce waveforms that are long and not very directional. They also work better when they push "against" something that can transfer some of that kenetic energy.
In most home theater setups, if the sub-box is setup with a side firing cone, the best placement would be to position the sub so that the cone faces a wall in the room. There are some high end subs that have 2 side firing cones, and in those cases, they are positioned at a 90deg angle to each other and meant to be positioned in the corer of a room, with the cones facing the 2 adjoining walls. However Most subs that I've used/seen have down firing cones, which point toward the floor to help transfer and enhance the low frequencies they emit.
The reason this is the case, is that some of the lower freq. that subs give off (ie: <30Hz) are nearing sub-audible to the human ear, and are more transmissive frequencies, and having them transmit those lower freq. to the structure of the house helps you "feel" the bass, that your ear may not hear as well. Our brains are used to feeling lower freqs. as much as or more than hearing them.
I wouldn't point it up, you won't harm anything, but I think you will get less bass response from it in that orientation, as you would be minimizing the transmissive properties of the low freqs. Instead, rotate it to point down. You would probably have to put small feet on it, as you have to keep in mind that the cone can move as much as 2" of travel depending on the freq. and volume and cone design, so you don't want the speaker cone to be bottoming out hitting the floor. You need a gap to prevent this, which is why down firing subs have 1" or so high feet on them so they don't rest directly on the floor.
If it's a smaller sub, like a 6" or 8" cone, the frequencies produced are not as low, and these effects are lower.
-jason
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Directionality comes from how your ears interpret mainly two things: the loudness difference between the same sound in both ears, and the time difference between the same sound entering both ears. At low frequencies, where the distance between the ears is well below a half wavelength of the sound, the human auditory system uses primarily phase difference between sound received in both ears to tell direction.
Key to understanding all of this is knowing the wavelength of the sound. Roughly, it is 1000 feet / frequency. Example: 50 Hz has a 20 foot wavelength.
Below 200 Hz (5 foot wavelength), this no longer works effectively because the phase difference is too small to be detected, and below 80 Hz (12.5 foot wavelength) it doesn't work at all. This applies no matter if you're in a car, a room, or the Grand Canyon. See a simple explanation at http://en.wikipedia.org/wiki/Sound_localization
A 15" subwoofer and a 4" subwoofer both playing a 50 Hz sound will produce exactly the same wavelength sound, just to clarify.
A single high-frequency sound, say 1 kHz, will produce a complex interference pattern after bouncing off various objects on the path to the ears. This can cause both loudness and phase differences at the ears that are highly variable depending on exactly where the listener is. Try it sometime when you hear a high-pitched single frequency sound; move your head just a few inches and you will find the "source" of the sound coming from widely different directions. Ambulances using multiple frequencies reduces this (they will form more of an average) and adding white or other broad-spectrum noise will average sufficiently that the ears can correctly take the cue of loudness difference to locate the source.
A long-throw speaker is designed that way because it is likely a smaller driver and needs to move a greater distance to move the same volume of air as a larger driver. It has nothing to do with where it rests when placed vertically or horizontally. It is difficult to make long-throw speakers linear because it is difficult to make a uniform magnetic field with sufficient strength over the full range of movement.
The driver suspension (the "spring" force that keeps it centered) is far stronger than the weight of the cone. It is generally designed to have a certain spring force acting against the spring action of the air inside the enclosure. "Generally" because there are many options for designing drivers, enclosures, and alignments to achieve specific goals.
As one poster mentioned, all this is covered in Thiele/Small theory and parameters. Long/short throw, stiff/loose suspension, driver material and weight, magnet and gap size are all design parameters to achieve a certain set of tradeoffs that can be analyzed with Thiele/Small theory.
Placement of the subwoofer interacts with the room (walls, ceiling) to form interference patterns throughout the room. What matters primarily is the placement of the subwoofer (and how its sound is reflected/absorbed by the walls, floor and ceiling), and not so much which direction it is pointing. Yes, in some cases there can be additional loading factors; if pointed down and a small gap exists between floor and cabinet, it places an additional load on the speaker that it was not designed for and will change its frequency response. There may be vents that require some distance from a wall or floor for the same reason. But pointing to the side vs. up should make no difference.
Place a subwoofer in a corner and all its output reflects close to in phase with the primary wave at low frequencies. This will "sound" louder (in most reasonable cases) than putting a subwoofer in the middle of the room where its sound reflects from walls, floor, ceiling at widely different phases from the primary wave. This will probably "sound" less loud, but may sound "flatter". It's all dependent on specifics. Again, the way to look at it is by wavelength of the sound. At 30 Hz, wavelength is 33 feet, and it doesn't matter whether the sound came from the side or top or bottom, that's going to be a path length difference to your ears of maybe 2 feet. At 200 Hz (5-foot wavelength) that will make a big difference.
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In order of importance:
1) sub woofer frequencies are not directional and must move "air" in two directions - don't block either the direct or indirect air portals. 25 mm clearance from portal to a wall or floor is good, 50 mm better.
2) minimize any tendency to vibrate the case. This is best done by adding lots of weight as in adding a 50-100 mm cement skin which will translate to all power being used to move air, not shake the case. If your sub woofer sounds good at 20 lbs, I'll sound great at 200 lbs and over a much broader range of vol levels.
3) avoid setting sub woofers on carpet if an air portal is down-facing, but if necessary, raise the case bottom at least 25mm above the carpet surface with legs made of steel bolts sharpen to a point to penetrate the carpet and rest on the floor below. Use levelers where needed.
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Laying it on another side will not harm it, nor materially affect the sound.
The only thing that you might take into account is to mechanically isolate it from hard surfaces, using either stick-on rubber feet, or placing it on a sticky mat.
(It will vibrate itself from a piece of carpet or suchlike.)
You can even place it under a sofa or bed without detracting from the audio.
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A farmer accused of cattle rustling is the first American to receive prison sentence using predator drone assistance. Moo![^]
It was broke, so I fixed it.
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Nice writing, thanks for sharing.
It was broke, so I fixed it.
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Thanks. It's one of the first pieces I've written, and definitely needs a rewrite now that I have more experience. Still, I rather like the basic story idea.
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Interesting that he was found innocent of rustling, but was convicted and sentenced essentially for resisting the authorities.
If your actions inspire others to dream more, learn more, do more and become more, you are a leader.-John Q. Adams
You must accept one of two basic premises: Either we are alone in the universe, or we are not alone in the universe. And either way, the implications are staggering.-Wernher von Braun
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.-Albert Einstein
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And apparently, have been for a while[^], with newspaper headlines as far back as 1893 announcing this "new" fad among the genteel and educated classes.
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Got reactions somewhat like that when I got my Planescape Torment tattoo (1st tattoo) at age 62. . .
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Got my first when I was in the army, now have 6
---------------------------------
Obscurum per obscurius.
Ad astra per alas porci.
Quidquid latine dictum sit, altum videtur .
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Btw, these tattoos in one style? or different? because i have now 2 (first was tattoed year ago) and i want more but only one style limit me for choosen :-/
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I got my first tattoo to mark the occasion of my 40th birthday. So far, it is my only one, but I've been thinking of getting a second.
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Thanks. but no thanks. One fad I'll pass on.
If there is one thing more dangerous than getting between a bear and her cubs it's getting between my wife and her chocolate.
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I don't get tattoos; just don't see the point.
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." Red Adair.
Those who seek perfection will only find imperfection
nils illegitimus carborundum
me, me, me
me, in pictures
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People get tattoos to make a statement. I don't know if I want to say the same thing, ten or more years from now.
Software Zen: delete this;
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I suspect you are spot on. 
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." Red Adair.
Those who seek perfection will only find imperfection
nils illegitimus carborundum
me, me, me
me, in pictures
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Gary Wheeler wrote: People get tattoos to make a statement. I don't know if I want to say the same thing, ten or more years from now.
I wanted to get a tattoo when I was 13 years old.
I am glad I never followed through with that thought. At 66 years old I doubt that I would want to make the same statement. 
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Gary Wheeler wrote: People get tattoos to make a statement.
There's many different reasons - if you want to make a statement, better put it on a T-shirt 
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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I probably could have phrased the first part better: "Having a tattoo makes a statement." The remainder of my post still applies.
Software Zen: delete this;
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Write a program in your favorite language, then have it posted on your body. Then let other's who see it figure it out. They may even ask you what it means. Then, you have your chance to educate them about computer programming in your favorite language. Definitely an ice breaker.
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My principle still applies, because my choice of language changes over time. 30 years ago it would have been FORTRAN or 8085 assembly language. 25 years ago it would have been Ada, possibly LISP. 20 years ago it would have been C, 10 years ago C++, and now it would be C#. 
Software Zen: delete this;
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Interesting idea, just need to make sure there are no bugs in the code or you'll be made fun of by geeks for the rest of your life 
---------
Andre Sanches
"UNIX is friendly, it's just picky about its friends"
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