Polyfil

[Slammed 5,000+ posts]

here is an article for those who havent seen it:

http://www.moodym.com/audio/fiber.html

 

[Compjake 10+ year member]

I want to know this because I need 8cubs to run the 4 12's I want but I can only fit 4 cubes in my trunk.. so I I'm trying to figure out if I should just undersize the box's and run 4 12's or do proper size boxes and run 2 12's... and since I want 150+ db (hopefully) I would think 4 12's with polyfil would be better..

 

[pr-festiva 10+ year member]

i would like a show of hands on how many people over 150 use poly,,all the loud cars ive seen use proper size boxes that are hard and smooth inside,,my vote would be two good twelves and alot of power fireing forward with the trunk sealed off.Ask thorshammer on here about 150 in a trunk with 2-10's

 

[Compjake 10+ year member]

I was thinking about using 4 RE SX's or MT's, couldn't decide on witch one..

I cant fire them towards the trunk, only up.. my trunk is oddly shaped and will easily fit 4 12's side by side in 2 slot ported boxes..

But I cant seem to make the box big enough with the amount of space I got being 30x16x11 if I made the box 30x16x10 I could fit 4 12's side by side but the about of air space is too small for the SX or the MT's... and I would prefer to not use shallow mount subs, they don't seem to be as loud for the power (correct me if I'm wrong)

 

[pr-festiva 10+ year member]

is the dimentions inside or outside measurements?

 

[n2audio 5,000+ posts]

what I wanted to know was if 1 12 in a proper sized box would be louder or quieter then 2 12's in a the same box (box would be 1/2 the size it should be) and using poly fill.. I haven't seen an answer to this lol

According to Nousaine's calculations the optimal effective volume increase you can get is right around 40%.

You say you need 2 cf per sub, you only have space for 1cf per sub.

The most equivalent cf you can get using polyfill is 1.4cf

Since you're obviously going for SPL maybe you can just tune the box higher?

 

[pr-festiva 10+ year member]

30x16x11 would be .76 cube per sub if using 4 of them and that would be if it was inside dimentions.Or do you men two boxes that size?

 

[Compjake 10+ year member]

Sorry for the misunderstanding, It would be 2 boxes of that size (outside)

it has to be two so I can actually fit them into the trunk side by side, if I built one i wouldn't be able to get it in the trunk.

I thought about the higher tuning but I want to make sure I can run all 4 of them safely first, I killed a MOFO 12 by using a box that was too small and don't want to repeat that event. lol

 

[pr-festiva 10+ year member]

next question is the box going to block off the trunk opening? if so you more then likly wont come near a 150

 

[Compjake 10+ year member]

No, the side wall of the trunk is about 11 inches and the trunk door itself is about an inch over that because of the weatherstripping. I already thought of that one

 

[pr-festiva 10+ year member]

i mean the opening in to the cabin of the car not the height inside the trunk,if you block to much of that opening it chokes the air flow

 

[Compjake 10+ year member]

ohh, sorry.. no, the back seat is only held in by 4 bolts and has ton's of room on both sides for air movement.. I could probably pull off a hair trick with the amount of room that's there.

 

[pr-festiva 10+ year member]

from the size of your box it looks like sealed will be your best route

 

[Compjake 10+ year member]

Your not supposed to use MT's or SX's in a sealed box though.. I thought of that also.

 

[pr-festiva 10+ year member]

1 cube ported with a 3 inch aero 13.5 inches long is like 36Hz you can try it but its still not much port or volume for a 12