I seem to see alot more people puting thier subs up above thier theartre...in the ceiling.

WHY ???

what are the bennefits to this ?

wouldn't the sound travel into the beams, thus into the walls and shake basicly EVERYTHING that isn't COMPLETELY attached?

Are you talking about an IB subwoofer?

Are you talking about an IB subwoofer?

yes

IB subs require a large amount of airspace to displace large amounts of air to achieve the desired low frequencies (8hz or lower).

There's alot more to it that I'm sure some IB owners will clarify.

Like Spezzy said, it takes a LOT of space to contain an IB sub. Sometimes a closet works for smaller subs but it usually is an ajoining room, garage or best - the attic. Optimum space is 10 times the driver's combined Vas. For example, I'm building an IB sub with six 18's similar to the Fi Car Audio Q series. Each has a Vas of 268L or 9.5 cubic feet. Multiply that times six for the number of drivers and you get 1608L or 56.8 cubic feet. I need an optimum size of 16080L or 568 cubic feet. That's larger than most closets. It really easy to just install the manifold in the attic and cut a hole into the theater room. Cover the hole with a grill cloth and it virtually disappears.

-Robert

but would this create un-desirable results? My optimal idia of good home thearter bass, is being able to not only hear the lows, but FEEL the lows. Having the subs fire into the floor or whatnot would in essence create more "Feel". But having them in the ceiling would just shake the crap out of your entire house frame structure... and probably not even make it down to your seat...

It doesn't shake the structure if you build a decent box and secure it properly. No different than a box subwoofer needing a properly designed and enforced box. The sound waves will shake the structure but the box shouldn't.

Look at the bad boy subs being talked about on this forum, the conquest, the A7-900, etc. Now imagine 4 of those in a box 4 times the size (your attic). That is an infinite baffle and it's up there with the baddest mo fo sub's you can think of. :)
Just an example. There are all kinds of ways to achieve great bass. An infinite baffle is just a very efficient and in-expensive (relative) way to do it. And the simplest and cheapest of them can rival the best and biggest box subs.

but would this create un-desirable results? My optimal idia of good home thearter bass, is being able to not only hear the lows, but FEEL the lows. Having the subs fire into the floor or whatnot would in essence create more "Feel". But having them in the ceiling would just shake the crap out of your entire house frame structure... and probably not even make it down to your seat...

Bass molecules are heavy. They have no choice but to fall out of the ceiling and land very close to, if not onto your seat. :D

I have four 18's mounted in two manifolds. The opposed mounting in the manifold cancels out a large amount of the mechanical forces that would rattle the hell out of the house.

Check out Cult of the Infinitely Baffled. (http://ibsubwoofers.proboards51.com/index.cgi)

But having them in the ceiling would just shake the crap out of your entire house frame structure... and probably not even make it down to your seat... Not at all. When mounted in a manifold, the driver's forces oppose each other and cancel all mechanical vibrations. Only the sound (and a LOT of it) is directed into the room. Here's a good example of a manifold with opposing drivers.

-Robert

http://image2.frappr.com/pix2/i/20070202/6/9/2/6925382308373063003b245fbcf880220_large.jpg

rlj5242,
Can you post a pic of the room, I am thinking of doing this. I have a laundry room behind my front screen area. Nothing like cutting a hole on the front wall to access the laundry room. Will the laundry room have alot of bass as well?

Not at all. When mounted in a manifold, the driver's forces oppose each other and cancel all mechanical vibrations. Only the sound (and a LOT of it) is directed into the room. Here's a good example of a manifold with opposing drivers.

-Robert

http://image2.frappr.com/pix2/i/20070202/6/9/2/6925382308373063003b245fbcf880220_large.jpg

that looks like the basement to me :)



also, on a side note... my 2 12's at only 400w a piece produces DEFINATE ear destroying Rumble...down pretty freakin close to 20hz.

is the only reason people go with MUCH bigger woofers to create LOWER frequency ?

and due to being IB you need MORE of them to create the SPL desired ?

rlj5242,
Can you post a pic of the room.....Will the laundry room have alot of bass as well? Follow the link above to the Cult site. This pic was taken from there. The laundry room will have exactly the same amount of bass as the listening room. If it is smaller, then it will have more (louder and/or lower) bass.

also, on a side note... my 2 12's at only 400w a piece produces DEFINATE ear destroying Rumble...down pretty freakin close to 20hz.

is the only reason people go with MUCH bigger woofers to create LOWER frequency ? A large IB has significant output down to the single digits. The only thing with more output down low is the Thigpen Rotary sub. There is also a benefit of not having an enclosure to color the sound. These manifolds just separate the front wave from the back wave the driver produces. Other than that, the driver relies on just the suspension and magnetic force to control the cone.

and due to being IB you need MORE of them to create the SPL desired ? Correct. This and many more questions are covered in the FAQ at the Cult site.

-Robert

as a rough Idea of output... would the same sub playing in a nice sealed box, require at least a second identicle driver if they where playing IB, to reach the same SPL ?