I am preparing for the arrival of some very beautiful car audio equipment in March and am trying to get my sh*t together so I can get it in quickly. My box is big enough for 2 12" subs, which will be Type-R's. I have one in now, as most of you know, and am getting it a little brother for some company. Now, my box is not divided. Right now I have a TOTAL of ~1.67 cu. ft. in that box. I have had lots of people tell me that i need to divide the box before I add the second sub or the subs will fight for air . I have also been told that more boom comes from an undivided box, and more sound quality comes from a divided box . Any truth to either of these "facts"? If I divide it I will loose that more airspace from the divider, and at the size the box is now, i cant afford to loose anymore airspace. Also, if I dont divide the box, the subs will share the whole 1.67 cu. ft, insead of being sealed off into .84 cu. ft. per sub. WHAT SHOULD I DO?!?!

 

a divider will help brace your box, but it wont matter either way as far as sound.

 

Since your box is symetrical, I'd say divide it. With boxes like mine that are non-symetrical, it's better to keep it undivided unless you are absolutely sure you can wind up with 2 100% equally sized chambers.

Anyway... whoever said they're "fighting for air" is a moron. All the sub sees is damping force caused by the air pressure within the box. That's IT. 2 subs in a 2 cubic foot chamber will see the same damping force as 1 sub in a 1 cubic foot enclosure.

One thing I would suggest however, is that you build a bigger box. I think a shared are a of 1.6 cubic feet is too small for those Type Rs and will result in a boomy, tubby sound.

 

The person who said the subs would fight each other might have been thinking if you are running a left and right sub setup, than it might make a differance (i could be wrong), But if you run a bridge system that you wont have to worry about that. Also about the devider, the only time you would notice a differance is if one sub blew out, because you would go from 2 subs in a 1.6 enclosure to 1 sub in a 1.6 enclosure. If you devided it and one sub blew, the working sub would still have the right amount of space.

 

yeah, if the subs are mono and their moving the exact same way, it'll be fine... the only thing i see with a divider? would be if one of your subs gets burned up, the other one has it's own air to work with....Like Jim said, if you have the symmetry, go for it.

- Andy

 

the subs will not fight each other in mono, u can use your current box with out making i divided if you plan on a mono set up, but the real problem is 1.67 cu fet for 2 subs are not that much, so with alpine type r's you might want to redo that box so you have a total of 2.3-2.7

 

He definately does not have the space to do that with that kind of box. If he did somehow figure ou a way to keep the same configuration and get 2.3 or more, the symettry would be gone.

 

jim, wouldn't having a smaller box effectively make the sound tighter? this is a very general question, but if the airspace is less, then the air behind the sub is more compressed and makes the sub suspension more rigid. that is why when subs go into smaller boxes they usually need more power, because the sub has to compress more air.

just asking, and since you seem to know your stuff, i hope you can answer my question. thanx.

 

I have been thinking of a way to make the box bigger, and I think I have an idea. Im not good at converting my ideas to words, so bear with me please. Take the top picture i posted, and move the top up so it is over the ledge of the well by maybe 2 inches. then extend it back so that it touches the rear seat, and the whole ledge back there will be part of the box, as well as the normal box. Here is a pic, sorry for the crappy paint job, dont have photoshop (yet ) Hop the pic helps! Im not sure how much airspace that gives, I would hope that it would be more than 2.0 cu. ft though.

 

4got the pic...my bad :P

 

that box is not a very good setup. with the sub playing into the trunk like that a lot of the sound will get trapped. build a box that the subs play into the hatch glass and it will be 2x-3x louder.

 

I disagree. read here. I have also played with the sub placement and have found this position to be the loudest and hardest hitting.

 

I saw that same sight a few years ago, and that is why I'm doing my rear facing box, that and also that way no body can see my speakers.

 

Sorry, that's not correct. The only situation that will cause what you say to be true is if there is insufficient ventilation for the area that the sub is firing into. If that happens, it can result in a 4th order bandpass type of situation, which won't produce desired results. But... as long as there's enough space that an artificially high air pressure doesn't build in front of the sub, it'll sound fine, and will be as loud or louder than facing them toward the glass. Under no circumstances will changing the direction the subs face make it 2x-3x louder. Under ideal circumstances, you may gain 3dB.

 

That is from your linked to article. What the caricle says is very true for cars with a trunk. Not a hatch back like a 3rd gen. I had a pair of 12s in my car mounted similar to how yours is setup (no top cover plate though) and they sounded like @$$. later in time i had cheaper speakers in a plate that sounded much better with the same amp, ; (. Either way the best setup I have ever had was 2 15"s in a box on the rear seat (folded down) facing into the hatch.

 

I would love to argue with you over this but there is really no way to win this arguement. It is all based on the listener. What I think sounds good, you may not. But what you think sounds good, I may not.

But on a side note....they say "Which way to aim a trunk mounted woofer box in a car." You say "with the sub playing into the trunk like that a lot of the sound will get trapped" You say trunk, they say trunk. Everyone says trunk.