MM124 air space questions

Big Sexz

Hello all, I know the recommended air space is .88 for each of these. Does it matter how I come up with the .88? I have air space, but not the perfect box by far. It is probably going to be molded kidney bean shape or something like that. Is that going to kill me on sound?

exalted512

nah
as long as its sealed tight and ideally u need about 2" behind the magnet
-Cody

Big Sexz

Well I built 2 identical boxes (1 4 each sub) and I know I didnt have enough room. I'm thinking it is only around 800 square inches, but that is only if my math is right. The box is sealed air tight.....very tight. How bad is this going to be for the sub? There just isnt a lot of room in the compartments. The subs are getting a C300.2 each, but nothing has been tuned yet. With that little airspace will it damage anything? Here is a rough diagram of the enclosure. This is all I could fit in the space. Please feel free to double check the cubic inches.

neomagus00

that is exceedingly small... um... can't you put like a hollow post in there somewhere? like a vent, sticking up out of the box, but capped and sealed. gives you more airspace in an unusual way.

on the plus side, it'll be tough to over-drive those things, at least mechanically. heat could be a different thing.

Big Sexz

I was just thinking that I could probably come off the side a little bit good for another 120. Think that would be worth a new box?

The sub is asking for .88 or 1520 inches. After serious calculations at best I'm only going to squeeze out around 925 from 800. Is that extra 120 even going to be worth the hassel? Am I going to notice it at all in the sound? I know it will be closer to the goal, but we are talking about 54% of required air space vs. 61%.

exalted512

what about going with the 10s?
i would say squeeze every little bit you can out of it
and stuff it with poly fill
-Cody

Big Sexz

Originally posted by exalted512
what about going with the 10s?
-Cody

Cant do 10's. Have to make the 12's work somehow. I have not given up yet on a new box design. I am going to look at it again tonight to see how much I can expand upon what I already have. One way or another, I will hit the mark. Just not sure how.

exalted512

try to get it at least to .7
then put about 2lbs of poly fill in each chamber
-Cody

neomagus00

but don't buy the polyfill from an audio store, they'll charge you out the **** for it, go to a crafts store or walmart maybe or something like that.

Big Sexz

Well after spending the night looking and measuring with the box in the compartment (big help for us visual folks) to see where I can grab up space, with a push here and a pull there I now have plan for just under 1400 cubic inches :eek: He11 YES!! I might have to do some cutting on the car to squeeze the box in, but with the box in there I shifted it all the way to one side and found about 9 inches more to play with. The construction starts tonight! To bad about the other boxes I built. To be honest I really enjoy building/challenges so I dont mind it, plus 3/4 inch MDF is under $20 a pop so it is not breaking the bank.

neomagus00

since you have found all this new room, you can now ensure that there's adequate clearance for the magnet in the box. just a thought.

Big Sexz

All of this new room is spreading out, not in depth so the magnet for all intensive purposes is still only about 1/4 inch off the box. Well after construction I now have a box that is around 1300 and it actually fits. Thats .75 which is way better than the .42. Granted I had to bend some metal but it was nothing structural so I'm not too worried. Once the box is in and parmentally mounted I will bend the metal back into place. I still have to build the other box tonight.

Cody -- I'm taking your advice on the poly fill. 2 lbs. per box is going to be stuffing it full and tight. Are you sure about the 2 lbs? 1 pound of this stuff is the size of a reg pillow. I went to Jo Ann fabrics and the stuff was only like $2.50 per pound so that worked out great. Hopfuly the sound will too.

Jeff
BSZ

neomagus00

since you managed to increase the size of the box by that much, you can use less polyfill, say a pound. loosely attaching it to the walls to keep it away from the sub may not be a bad idea.

exalted512

id put a pound in it, no less
-Cody

Big Sexz

Hey man I already bought 4 pounds of this stuff. Will it hurt anything if I stuff the full 2 lbs in each one?

neomagus00

it wouldn't hurt anything, no. try both - put a pound in and see how it sounds (after proper break-in) and then add another pound and see how that sounds. then pick.

if you like only 1 pound, you're only out five bucks, so no biggie.

LittleCar_w/12s

Just try to give the magnet some clearance for heat purposes.
-Jerry

exalted512

its recommended that a pound per sq. foot, but youre a little low on the size and poly fill helps make the box seem bigger, i wouldnt put more than a pound and a half in it
-Cody

Big Sexz

Originally posted by LittleCar_w/12s
Just try to give the magnet some clearance for heat purposes.
-Jerry

I will keep this in mind. Thanks for all the help guys, I really appreciate it.

Jeff

MacLeod

Originally posted by neomagus00
that is exceedingly small... um... can't you put like a hollow post in there somewhere? like a vent, sticking up out of the box, but capped and sealed. gives you more airspace in an unusual way.

Dude! Thats a damn good idea and Ive never thought of it! Ive got severe space restrictions and am having trouble finding extra cubis feet as well. Using something like that may be a lot easier if I cant find another solution! Good thinking!

LittleCar_w/12s

Yall have seen neo's car right:

exalted512

i thought i had too much free time...
-Cody

neomagus00

hahaha... that's freakin awesome ...

AustinKP

Dang, I want MY car to have a smokestack! If someone can tell me how to keep it from leaking, I'm doing it tomorrow!

neomagus00

just put on a snorkel and act like everything's normal - this works much better if you drive a sport compact and you use a 4-inch intake...

you can detail the top to look like a smokestack; paint the side of the car to resemble a paddlewheel and you're set...