9' X 12' Room... Is there even room for a sub???

[Cool Mr Steve]

I'm currently in the process of planning out my Modula Mt's, but the question of a subwoofer for my room has been weighing me down. The room I'm putting my speakers in is really small (9' X 12'), and that sucks, but it's what's available to me. Aside from the problems I'm going to be facing trying to correctly position my speakers, I'm anticipating the problem of a subwoofer. I would love to be able to throw a nice big subwoofer in there, but I have no idea where I'd put it. The corners of the room will be taken up by my speakers, so that would be tough. My other thoughts were that I could make a side table (to the side of my couch) that could double as a subwoofer, or an ottoman subwoofer. I'm not sure what the concensus is on doing subwoofers of these types, so my question is what would you do in this situation? Do the subs placed next to the couch or directly in front of you (the ottoman) perform decently? Do I need to somehow finagle a subwoofer into a corner? My only other option is to stick a subwoofer in the closet that is in the back of the room (one of the double sliding panel style closets), next to the entrance. I've never heard of that being done, though. Any help?

*EDIT* With my room dimensions, I have no idea what the box size limitations would be, if I could fit a box at all. It could be fairly large if it were a side table or an ottoman, but it would have to be pretty small if it were to be a corner affair.

[joecarrow]

Are you doing home theater, or just music? If it's just music, I only see the need for a sub if you're really into electronic music or pipe organs.

Generally, subwoofers that are near the listening position are not a problem. The nice thing is that if they're close, they don't have to be as loud.

Have you considered the Aurasound bass shakers?

[Cool Mr Steve]

The main purpose of this room will be home theater, but I will use it a good deal for music. I have read into the bass shakers but it's not really what I'm after. I would really like to hear opinions about a subwoofer at the side of the couch and what kind of performance I could expect from that kind of placement. I don't want it to sound incredible on the left side of the couch but dead on the right side of the couch.

[clearwaterms]

my living room isn't much larger then yours. I have a 5.1 in a box setup from athena that uses a small subwoofer. I placed it next to the couch and the room sounds fine as a result.

I would normally suggest looking at like a 8" sub cub, maybe even a passive radiator affair (I think you can get a small box with a passive radiator, but I would suggest you talk to somebody else first) but the MT's have a 7" woofer, and are crossed pretty low, so I am thinking something like a 12" in a sealed cube might be better, and then slap like a PE 240 watt amp on it... it's an idea

[Mazeroth]

I'd finish your Modulas and get them set up in your room. See how you like it without a sub. You can always build a sub later on if you need to.

There's no reason to worry about a problem that you don't have, yet. Think about it. What if you did build a sub and then found out you really didn't need one? That would suck :lol:

[Jonasz]

My friend has a room that is aproximately 16*16 and he has four 12" (140 liters) subs in there. The thing is to find the right place for them. He had an acousticer (hehe dunno the word) there to measure and they did adjust a bit. The thing is, four modules sounded WAY better than two! You just had to place them on the right spots...

[warnerwh]

In all rooms we have nulls and peaks. Bigger is better but they are still there. The most important thing to do would be to make some bass traps. There's plenty of sites showing you how and they're inexpensive. If you can get away with it I'd use at least 4.

Another big helper is either the Behringer DEQ 2496 or the BFD that I've noticed alot of the people here use. There's a good reason for that, it's because your room needs the help and bass will sound much better with the outside help. For the money I think these Behringer devices are bargains.

[cgr]

Having had a sub in my home theater for almost a year now I wouldn't want to go without it. I have an old set of Cambridge Soundworks original Ensemble(satellites with 8" bass units). I built a 3.5 cubic ft sub tune to 21 hz with an ascendant audio 12" assassin and PE 240 watt amp. The sub adds so much to the experience of watching a movie for me.

My room is similar in size to yours, I have the sub in a corner. If I was build it again I would consider making the box a bit larger and putting a granite top on it to make a table. If I remember correctly I could have built 4.5 or 5 ft box and tuned it to 19 hz.

[Dennis H]

Brian Bunge built a cute little 14" cube sub with a plate amp and a Dayton RS 10" HO driver. Not much bigger than a bookshelf speaker really. He says it sounds pretty good. If he doesn't see this thread, you might PM him for details.

I'd strongly suggest using a sub for the LFE channel if you build the ported Modulas. The drivers unload below port tuning and setting the sub to 'none' for movies will kill the woofers of the front RL.

[wmilas]

Keep in mind that a 9' x 12' room limits the largest wavelength produceable assuming its a closed room. No matter the size of the subwoofer you wont be able to produce a wave length larger than the wall with the largest dimension.

Wavelength = speed of sound/hz.

122 inches = 13,503.94 in/sec / Xhz

Solve and Xhz = 93.78 hz. Anything below 94 hz is pointless as the room wont support it. Its amazing how many people forget this simple rule

[Dennis H]

Its amazing how many people forget this simple rule

Perhaps because the 'rule' is a fallacy.

Take your sub in a closet with you or stick it in your car and I guarantee you'll hear low bass just fine. In a perfectly sealed room, bass will increase at 12dB per octave below the lowest room mode. Most rooms aren't tightly sealed and perfectly rigid so the increase isn't that much but most rooms still get a certain amount of 'room gain' below the lowest mode.

[ThomasW]

Anything below 94 hz is pointless as the room wont support it. Its amazing how many people forget this simple rule

Then it must be beyond belief when I place my test mic 1" from the dustcap of a sub, and measure output below 20Hz?..... 8O :B

[wmilas]

Ok, so I'm a newb... and willing to learn.

How exactly is this possible? I thought the full wavelength had to be able to be produced without having numerous null nodes, massive phase shifting and refractive oddities?

I'm not being sarcastic I'm seriously trying to understand. Where does the 12db bass boost come from? I assume there will be nodes where the reflections would be in phase causing a 3db boost but 12db? Wouldn't there be many more null nodes at frequencies lower than the room mode?

[Dennis H]

Our ears hear changes in pressure, not waves. Below the lowest mode, where the wavelengths are long compared to the room size, the sub is pressurizing the room. Consider a perfectly sealed room and you hook up a DC (0 Hz) battery to a sealed sub. The driver moves out and changes the pressure in the room. That change in pressure can be measured in dB SPL.

The 12dB thing comes from the fact that you generate the same dB SPL (pressure) in a sealed room with the same cone displacement no matter the frequency as long as it's below the lowest room mode. In free space, the same displacement rolls off at 12dB/octave. Put another way, to get the same SPL in free space, you need to move the cone 4 times as far when you go an octave lower. So, if your sub is tuned to be flat in free space, you will experience a 12dB/octave boost when you put it in a small sealed room.

Edit, consider another example, headphones. The longest dimension inside tight-fitting phones is maybe something like 3" so, if the waves needed to fully develop, the lowest phones would play would be something like 4 kHz. Obviously phones can play a lot lower than that. Same deal, the phones are pressurizing the small cavity and pressurizing our ears.

[wmilas]

Ok I understand the pressurization.. never thought about it that way but it must be true. Still trying to understand the 12db boost. Are you assuming a 2nd order crossover and is that where the 12db come from? Ie the rolloff is pushed farther to the left on the curve? If so how far left? It has to rolloff at some point doesn't it?

[Dennis H]

No crossover. A cone moving the same distance at all frequencies rolls off at 12 dB/octave in free space. The same cone doesn't roll off at all in a perfectly sealed room. So the sealed room is giving a 12 dB/octave boost.

In the real world, with real rooms, the boost is much much less. If you look at the popular EBS (extended bass shelf) ported subs, the lowest frequencies are about 6dB lower according to the models which assume the sub is in free space. Put in an average room, the room gain boosts the lows and the sub ends up being about flat in the room. So, it's 6 dB total boost, not 12 dB/octave.