IB Help...

[reible82nd 10+ year member]

Hey everyone,

Just got done putting a wall in my trunk and running my PPI A.8SQs IB, it sounds good but I have few questions. I mocked up the wall **** near perfect so it's pretty sealed, it sounds good but seems to sound a bit "choked out." I'm also running a pair of 6x9s in the back dash too, so they're running IB in the trunk as well. With everything sealed off, am I supposed to "port" the trunk somehow? If so, how do I calculate the diameter and length of the port? I've attached some pics to bring everyone up to speed. Any advice would be greatly appreciated, thanks!

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[keep_hope_alive Premium Member]

you miss the point of IB. it's not sealed if you have speakers back there. you need to build enclosures around the rear speakers, or remove them and seal off the opening. those speaker cones are near invisible to bass frequencies, so bass travels right through the rear speakers, causing a lot of cancellation.

you cannot run rear deck speakers with "IB" subs.

adding a port would further defeat the purpose. you want to fully isolate - meaning air tight/water tight - the trunk from the cabin. anything that flexes (speaker cones) is cancellation. you cannot have too much mass separating the trunk from cabin. i have about 5 layers of deadening on my rear deck and 3/4" MDF closing off the rear holes. see my build log for how i put an IB wall in.

 

[keep_hope_alive Premium Member]

further, you are not sealed to the metal, you are "sealed" to the carpet panels. bass travels right round/through the factory carpet and leaks around the sides - causing more cancellation.

you'd be better off putting a box around the back of that board.

 

[reible82nd 10+ year member]

Thank you for not totally destroying me man, that was quite professional. I don't have any experience with IB stuff, clearly this was a feeble attempt at setting one up and I failed. I probably should've done more research before trying to tackle this...I like the wall though, maybe I will just enclose the subs in the trunk and leave the wall there. Thanks again.

 

[pickup1 5,000+ posts]

Plus those weren't made for i.b.either...if your going to use those an enclosure is king..

If you want to go i.b. Look at 12-15s...cone area is best for that...i did 2-10s in the rear deck of my altima and liked it..im kinda a bass head though..

I was going to buy those 18s we talked about...thought they may be too sloppy for me..