My current HT room is over a two story garage. I have two Orb Super 8 subwoofers, and they are both downward firing. The problem I run into is that the subs have to work really hard to fill the room up with bass, even with two of them (room is about 20x14). Their ports fire downward into carpet, and I think this only contributes to the problem. Is there any sort of material I can put under them to keep more of the sound in the room and not so much of it from going straight into oblivion? Can I make some sort of extra/external enclosure?

For the record, I have tried several different spots in the room, but have had no success. I have also had both subs in a college dorm room with cement walls and flooring, and of course they shake the entire room from lights above (and below :D ) to the windows: so it's not a power issue either.

Thanks in advance.

What kind of floor do you have? If it is a lightweight wood floor, you may be sending all your bass energy through it to the garage.

What kind of floor do you have? If it is a lightweight wood floor, you may be sending all your bass energy through it to the garage.

Exactly what you said, a lightweight wood floor. And that is what I'm trying to prevent, because currently most of the bass energy is going into the garage. Any ideas?

That floor and perhaps the walls and ceiling as well will soak up a lot of power, no question. We don't know what SPL you hope to achieve, but 8" subs would be working hard in a 20 x 14 room.

However, just for the heck of it turn the speakers on their sides so that the port now fires to the left or right or up and the driver continues to fire into the room. If there is a big improvement then good! If nothing changes and you have already determined that the current locations for the subs are the optimal or only choices then you have no good/cheap solutions.

Low frequency sound will move the building structure unless it is massive or isolated. You could for example add a layer of concrete to the floor, or add a sub floor with sand beneath. This would reduce the transmission of energy through the floor. But let me ask how does the floor in this room differ from the other floors in the house? Most wood framed buildings with plywood or OSB sub floors are fairly live and about equal in sound transmission.

I use to have my set up in a garage witha concrete floor and it gave off amazing bass

Exactly what you said, a lightweight wood floor. And that is what I'm trying to prevent, because currently most of the bass energy is going into the garage. Any ideas?Most garage ceilings (your floor) are flimsy compared to the floors in domestic spaces. I once went to a home/showroom that was located over a garage and there was no bass despite the lavish equipment. Bracing the floor with additional beams and supports might help. Reorienting the drivers probably will not.

. Most garage ceilings (your floor) are flimsy compared to the floors in domestic spaces... Reorienting the drivers probably will not (help).
Rooms over garage space are not uncommon in my area (as compared to basements) but where they exist they must meet the same specs ( for live and dead loads) as for other living (and the additional requirement for a fire rated ceiling in the garage). From what you say this is not the general case.

I suggested reorienting the subs as a easy of test of the idea that the down firing port into a flexible floor was soaking up the bass, not as a likely solution.

I do however stand by the idea that without some idea of the volume of the room, the room dimensions and/or some analysis of actual output and the SPL desired, we can't rule out the possibility that that two 8" subs just won't carry the water. ;)

Thanks for the suggestions! I'll try them out tomorrow afternoon, considering it's 2 in the morning right now. And I believe that the floor above the garage is the same as throughout the house (its only 7 years old or so). Right now the subs are separated by about 12 feet width wise, and sit in the back two corner of the room (projector screen up front). And I was wrong about the room specs. The actual dimensions are about 16 by 12, so two 8" subs should be able to do the job.

The fact that it's TWO subs makes me think about phase cancellation. Have you tried checking for this? (Switch the 'polarity' of the wires coming into the sub. Or, flip the phase switch, if you have one. (but only on one)

It's not a super likely theory, given some of the other things you mentioned, but it bears trying out.

As for the weight of the floor--that's not going to be it, at least not in a home that was built to code. I have two rooms over my garage and they employ the exact same TGI joist construction as the rest of my house (watched it being built) so unless this was a DIY job, I wouldn't pursue that line.

It's cheating a little bit, and I would try the 'laying them on their sides thing first, but if you throw your subs in the corners, you'll get more bass than you can handle. Really. And since it'll be using the corner of your room as a firing horn, you may not get that much more additional bass downstairs.

S.

Rooms over garage space are not uncommon in my area (as compared to basements) but where they exist they must meet the same specs ( for live and dead loads) as for other living (and the additional requirement for a fire rated ceiling in the garage). From what you say this is not the general case.Well, I have no statistics but only my experience and that is all from this other segment of the country, as well as based heavily on old construction. Nonetheless, I also wonder if the large, open and resonant space of the garage, itself, does not play a role in its ability to such bass energy out of the space above.

I do however stand by the idea that without some idea of the volume of the room, the room dimensions and/or some analysis of actual output and the SPL desired, we can't rule out the possibility that that two 8" subs just won't carry the water. ;)Agreed.

Nonetheless, I also wonder if the large, open and resonant space of the garage, itself, does not play a role in its ability to such bass energy out of the space above.


This got me thinking. :D Building codes are concerned with strength and impact vibration/noise; not in room acoustic artifacts. Where STC requirements exist they are famously ineffective with low frequency sound.

I did some quick research and learned that typical light framing will yield a floor with a resonant frequency of between 10 and 30 Hz. Floors are also very responsive to the second and third harmonics. Longer spans and higher columns lower the frequency.

So I think you are correct. The volume in a two car garage is a resonance chamber tuned to low frequency, or if it has openings a Helmholtz resonator, driven by sounding board tuned to subwoofer frequencies. It seems logical then that the acoustic energy driving the sound board will be lost to the room.

Just my casual opinion, but this seems a bit fishy to me. Most any 2nd story built anywhere in the U.S. would all exhibit roughly the same characteristics, acoustically. A garage underneath isn't that wholly different from a family room underneath in terms of construction. Yet we don't hear of these kinds of problems from others. Hmmm.

Regardless, our friend is looking for solutions, and as interesting of a problem that is academically, I seriously doubt that he is insterested in shoring up the framing of his house.

So, try throwing them on their sides, try corner (or wall--not as effective as a corner) loading them and if all else fails, buy a bigger sub (or two). Trust me, it'll be a LOT cheaper than ripping up your floor.

But just my $0.02,

S.

Just my casual opinion, but this seems a bit fishy to me. Most any 2nd story built anywhere in the U.S. would all exhibit roughly the same characteristics, acoustically. A garage underneath isn't that wholly different from a family room underneath in terms of construction. Yet we don't hear of these kinds of problems from others. Hmmm.As I said, my experience is with older homes and, in these, there is often no ceiling in the garage, merely the underside of the floor above. This space wasn't built as a "bonus room" but as a storage space. None of this may be in conformity with current construction standards but it is common.