Airspace Problem .. please help.

 

CDeM
Unregistered guest
Hey everyone ...

I just built a box, and it is far too big for my sub. The box could easily fit 2 12" subs with room to spare. I currently have one Type R 12" in the box and really need to cut down the airspace inside the box for better sq. Any idea what I could fill the box with to acheive better sound? Eventually i will put another 12" in the box, but for now only the one. Thanks.
 

Anonymous
 
polyfill
 

Bronze Member
Username: Glasswolf

Post Number: 27
Registered: 12-2003
build a new box.
if it will have two 12" subs, divide teh box so each sub has it's own airspace.
 

CDeM
Unregistered guest
Well, part of the reason I built the box was for display. It holds the sub, 6x9s, and two amps on it. Everything is running fine except for the sub's sq is poor. Maybe I could fill the box with wood blocks or bricks or even sandbags?
 

Gold Member
Username: Glasswolf

Post Number: 1355
Registered: 12-2003
sand would be your best bet.
 

CDeM
Unregistered guest
excellent i'll try it out. I am going to order another type r 12" to throw in there soon, so that should take care of it. I was wondering if it is damaging my sub by pounding it right now with far too much airspace.
 

Gold Member
Username: Glasswolf

Post Number: 1366
Registered: 12-2003
well, if you check the T/S specs on that sub you might find that ideal airspace for it is like 8cu ft I'd bet. air suspension and vented enclosures etc essentially fool the subs into working in smaller boxes anyway.
best bet raelly is to divide the box so each sub has its own airspace.
also good if one sub goes bad.. the other still works fine.
 

Gold Member
Username: Glasswolf

Post Number: 1367
Registered: 12-2003
by the way, those subs aren't sharing air space with the 6x9s are they?
that'd be very bad.
 

CDeM
Unregistered guest
The 6x9s have no airspace as I have enclosed them in hard plastic containers. I am going to add another sub tomorrow, but it will be too difficult to separate the two. Are the subs more likely to become damaged if they're sharing airspace with one another?

I still believe the box will be too big for the subs. I have heard of throwing blankets in there to take up space...what do you think about that?
 

CDeM
Unregistered guest
well...to update...

I now have two Type R 12" subs in the box which is 5.2 cu ft! I believe the reccommended for the subs is 1 cu ft each, so i'm still way over. I was thinking about putting some 12 pack cardboard pop can containers with something heavy in them to take up space..maybe three along the back.


What do you think now?
 

Gold Member
Username: Glasswolf

Post Number: 1402
Registered: 12-2003
I think you need to build a proper box, honestly.
 

loud and low
Unregistered guest
iwould aggree, if you put hard stuff in there is going to rattle around and sound terrible. if you really don't want to make another box my suggestion would either use somethin like the sand bags, i wouldn't use the sheets they will prob act like accustic damping fluff which slows the wave down and makes the box accually act as though it were larger
 

Anonymous
 
You could also split the box and make 2 chambers, one for each sub and vent both chambers

you would get a lot more SPL!!! but not as much SQ...

thats what i'd do!!!.....dont know if your sub will work well in a vented enclosure....check the site and T/S on them....find out
 

New member
Username: Thesouphead

Post Number: 3
Registered: 02-2004
Maybe throw some pillow stuffing into the box?
 

Bronze Member
Username: Redskin

Post Number: 43
Registered: 12-2003
Hmmmm.......doesn't filling boxes with stuffing fool drivers into thinking the box is bigger? Not quite the effect needed in this case.
Do it right, build a new box. you know it makes sense.
 

Bronze Member
Username: Shouder

Post Number: 19
Registered: 12-2003
Yeah, you don't want to use poly fill or anything because like loud and low said it just slows down the sound waves to get an effect as though the box were bigger. Generally speaking ported boxes are bigger than sealed anyway so you could just divide the box and get close to what you need. Yet don't just stick another sub in there without a divider of some sort otherwise you'll run into troubles. For instance if one were to blow then chances are without a divider the other one could get damaged.

But im gonna have to jump on the band wagon with Redskin, and GlassWolf. BUILD A NEW BOX. and build it right.
 

CDeM
Unregistered guest
Thanks for the ideas everyone. Id build a new box but it took me two days and $50 to make. The box is carpeted and looks good, fitting perfectly in the trunk of my ride. If blankets wont work...how about anything heavy? i'm sure if its heavy enough it wont shake around, and whos going to hear it moving when the bass is pounding anyways?
 

jay amaro
Unregistered guest
the solution is simple, if your box is 5.2 cu ft now and if you put a divider board in the middle like it should have had to begin with and you will have just around 2.5 cu ft for each or the one sub which if the box is ported then you will be right where you want to be with it.
i understand your concern about cutting the box or partial disassembly since you put so much time and work and it is finished or well close but not quite properly finished then like glasswolf suggested earlier use (it really shoulda had one) a divider but there is some good news:
put a cleat just off center so that the width of the divider will be exactly centered once you found that measurement then attach a cleat inside the box the same height of your box height minus the thickness of the top and bottom panels (make sure you cut 4 of these).

now measure the dimensions of your divider board and cut it into 2 or 3 pieces that are continuous from front to back (use as few as possible) and this way you can build your divider from the front through the speaker hole.

attach each panel to the front and back cleats you attached earlier and when you get finished you should have it now divided.
also keep in mind that when you measure out your divider you need to add 1/8 of an inch extra for every cut you plan to make in the divider because of your loss due to the thickness of the blade and if you use a 71/4 handheld circular or small (home) table saw then use 1/8 or whatever the thickness of your blade is which if you use a 14 inch industrial table saw like i do then it takes off as much as 1/4 inch in each cut.

make sure to finish it off by attaching the outer 2 cleats now effectively "sandwiching" your divider between the cleats both front and back and on the left adn right side of your divider.

make sure to use screws and glue or liquid nails at every connection especially between each section that made up the divider (hopefully you can find a way to install it in no more than 2 pieces) and it would be a good idea to brace the divider in "its" center from top to bottom now or use a cleat to "stitch" the seam from the 2 or however many sections you used. still making sure to glue or liquid nail every and all connections even if you use screws (never use nails).

if you did use wood glue then be sure to caulk every seam!
skip that step if you used liquid nails or any other panel substrate adhesive.

that should effectively save your 6x9, 2x12 box and also make it stronger and get it to within the proper dimensions for that sub as well as preserve the integrity between both subs which is very important.
now you can take all the time in the world you need to put the other sub in but in the meantime the one you have will sound good in its 2.something cubic foot side of your box.
jay
 

Rhythm44
Unregistered guest
If the box is built, don't worry about dividers. Assuming both drivers will be the same, all is well.

You might keep it turned down a bit until you get the second driver in there though, larger boxes come at the expense of power handling. Your sub might be jumping out of its voicecoil :D.
 

CDeM
Unregistered guest
lol, I have two Alpine Type R 12" subs powered by a RF 501bd amp putting out 600W (mono). U know the water jugs they send to your home? One of them fits perfectyly into the sub hole, and fits nicely inside the box. I put one of those plus a rolled up sleeping bag inside the box. I havent hooked it all up yet tho.
 

Rhythm44
Unregistered guest
That water jug was a good idea, lightweight and still does the job. That box must be huge if you can fit all that junk in there :D.

 

CDeM
Unregistered guest
lol, you have no idea. I am able to jam two of them in there. Both are able to contain 5 gallons of water, which equals only 0.67 cu ft.
So together they take up 1.34 cubic feet, and leave me with 1.86 cu ft to fill lol.
 

CDeM
Unregistered guest
Maybe I measured my box the wrong way. 5.2 cu ft seems too much. Maybe someone could give me the proper measurements if I give the info.

height: 17 inches
base: 35 inches
top: 14.5 inches
angled front: 20 inches
 

Bronze Member
Username: Shouder

Post Number: 23
Registered: 12-2003
Thats only one side isn't it, we need the length of the entire box.
 

Rhythm44
Unregistered guest
That looks pretty close, if you allow for the thickness of wood, the volume the subs will take up, etc, it might be a tad smaller... But I counted just over 5 too.
 

Bronze Member
Username: Tbone

Post Number: 29
Registered: 02-2004
Help me out here, how did you come up with the length and width of the box?
 

CDeM
Unregistered guest
i just measured with a tape measurer
 

Bronze Member
Username: Tbone

Post Number: 49
Registered: 02-2004
Well, what were the measurments?
 

Bronze Member
Username: Shouder

Post Number: 29
Registered: 12-2003
CDeM, tell me if im wrong somebody, but don't we need at least one more dimension in order to figure out the volume. Don't we still need to know the entire length of the box.
 

Bronze Member
Username: Shouder

Post Number: 30
Registered: 12-2003
CDeM, tell me if im wrong somebody, but don't we need at least one more dimension in order to figure out the volume. Don't we still need to know the entire length of the box.
 

Bronze Member
Username: Tbone

Post Number: 54
Registered: 02-2004
Yeah, that is what I am trying to get out of him, then we can really help him. As for objects to put in a box to fill airspace, I found that Jimmy Hoffa added just the right dampening.
 

CDeM
Unregistered guest
Sorry guys, i'm confused. The length would be 35in wouldnt it?
 

CDeM
Unregistered guest
ok ok, im going to try this one more time....

length:35in
height:17in
Top:14.5in
Base:24in
Face(front):20in
 

Bronze Member
Username: Shouder

Post Number: 31
Registered: 12-2003
I don't know guys correct me if im wrong but i got 6.63 cuft. Thats a pretty big box. Even if you put in a divider its still on the big side. Either way if your going to keep it your going to need to put in a divider and probally port it. Get ahold of GlassWolf for porting equations. Otherwise sandbags sound like a good idea. try that.
 

Bronze Member
Username: Tbone

Post Number: 59
Registered: 02-2004
Yeah, that is what I came up with also. With that much room putting in a divider shouldn't be a problem.
 

Bronze Member
Username: Big_l

Surrey, Surrey England

Post Number: 13
Registered: Feb-04
who is this CDeM guy, sorry mate all due respect and all but you are talking nuts, you want your subs to be more sfficient right? well putting sleeping bags and shite in there will not sort your problem, it will make it less efficient as the subs think they are in a bigger space!!! like redskin and tim shoulder said, if you put up a question then you should at least read the answers man!!!
 

CDeM
Unregistered guest
Actually the sleeping bags worked mate. The bass notes are hitting sooner and harder now that they're in there.
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