DIY cheap and easy sound deadening (poly-fil)

MauiGideon · 02-09-2009, 02:11 AM

What bothers me the most is when I have my cell phone or something else in the door panels. If the music is too loud the vibrations rattle the door making the cell phone or whatever is in the hole rattle.. Really irritating...

Soooo did anyone also try this in the door panels?

awinter · 02-09-2009, 02:30 AM

So simple, but yet, no one has thought of this before - nice job! I was thinking of spraying foam or something but this idea sounds alot cleaner. Hopefully, this will quiet the noise when my subs hit.

gravebox · 02-09-2009, 03:03 AM

this is actually old school cheapo sound cancellation, the concept has been around for a long time.

you can buy big rolls of poly blankets at some old school performance shops and even at some Autozone and Advanced Auto shops.

be sure to keep some of the cavities around your speaker drivers open, the poly fill will destroy the acoustic properties needed to produce decent sound.

as long as you don't block off the thru-thru vents in the back for the climate control, you shouldn't need to worry about moister.

a DAMN good idea is to use this as your sound deadening for the roof panel instead of actual sound deadening mat that adds alot of extra weight to the top of the xB. would be easier to use the poly roll blankets for the roof though.

just be VERY VERY VERY precise with your wiring on anything you do. if anything shorts out and a spark hits, that poly fill acts like saw dust in an open fire... it WILL become EXTREMELY dangerous. so if you're going to do any subwoofer setups or any new wiring of your own at all, you use the proper wire and proper methods to ensure no shorting or crossing happens such as soldering and shrink wrapping or if the wire it too big, do different lengths so that each pole's connecting point is guaranteed to be away from one another. as long as that's taken care of, you're good to go. this is actually something i've been pondering about doing, it's a great alternative to adding some 100lbs of matting to sound deadening the vehicle. it doesn't do AS good of a job, but it helps give a more "luxury" to your vehicle. more solid sounding doors, less road noise, people can't hear you talking inside of your xB anymore... you know how it goes

don't forget, there's the pillar panels too. use poly filler for the small cavities in the panels them selves and then cover it with a thin blanket of poly blanketing and those parts will be taken care of too.

at most, you'd be seeing roughly 5-7lbs of added weight at most throughout the xB with this setup.

MauiGideon · 02-09-2009, 03:32 AM

Quote:

Originally Posted by gravebox

be sure to keep some of the cavities around your speaker drivers open, the poly fill will destroy the acoustic properties needed to produce decent sound.

as long as you don't block off the thru-thru vents in the back for the climate control, you shouldn't need to worry about moister.

So where exactly is the thru-thru vents? and for the front side speaker doors how much space are you talking about

gravebox · 02-09-2009, 05:09 AM

thru-thru vents are the two removable small panels in the cargo area that have holes through them. those are the vent holes and access panels that are used for both climate control *in order to defog your windows and such, those vents allow the moister to escape to the outside of the vehicle while your ventilation system pulls in fresh air from the outside* and for access to the bulbs and bolting points for your taillight housings.

for space around the speakers, because they are only meant to play 60hz and above *i've tested them via RTA sound analysis* i would suggest keeping an empty cavity directly behind the drivers with about an inch bigger in cavity diameter compared to the mounting hole diameter... so for example, the front drivers are 6.5", you'd try for roughly 7.5-8" cavity diameter all the way to the sheet metal for optimal acoustics. you can line the very surface of the back sheet metal with thin poly blanketing to reduce outer sound distortion. the rear drivers are 5.25" so you'd do 6.25-7" diameter cavities for those.

in order to ensure driver lifespan and optimal performance, it's best to keep back pressure on the driver cone at a minimum level, otherwise the back pressure of sound coming back too soon will throw the cone off axis during play and can cause premature death of the driver voice coil. during loud play, the off balance of the axis can get so bad that the voice coil will begin to rub across the transducer and that can be a hazard, it'll either slowly fry and fuse it's self to the transducer or it'll fry quickly and possibly cause a spark... now whether or not the spark can get out of the spider... who knows, i haven't looked at the stock drivers my self, but if it's a vented spider in any way, the spark is able to get out and if it does... it will possibly ignite the poly filler. so, keep a decent acoustic cavity for the drivers and you'll ensure that you'll never be that unlucky person to get that 1 in 10,000 chance to have that issue happen.

Goosetavo · 02-09-2009, 09:29 AM

I overstuffed my rear quarters with the poly-fil... It did help canceling outside noise, but it also canceled too much of the rear speakers sound.

I didn't know about the thru-thru vents, so I will free them today. Thanks for the info gravebox... as always, your knowledge is appreciated.

MauiGideon · 02-09-2009, 01:12 PM

Think this would work just as effective in a xB2?

DarkTari · 02-09-2009, 01:54 PM

This is good info. I was just researching sound deadening last week !!!!!! (FatMat, Dynamat, Dead Zone, etc.)
I would think not to use this stuff in any of the doors due to moisture. Rear hatch, kick, quarter panels, roof & pillars all seem viable places for use.......

I guess this can be had at any fabric shop ????
`

gravebox · 02-09-2009, 03:03 PM

^^pretty much yeah,

the best thing you can do is create some way to seal off your filler from the door moister. if you can figure out how to seal the moister away from the filler, then it should be perfect.

this would work just as fine in the gen2 xB for sure, though i think there's sound deadening in those already isn't there? i'm not sure...

when you have the thru-thru vents open, look straight down and you'll see a small black piece, that is the second vent that goes directly outside. you wont see light through it, the vents are closed by a one way foam flap which only opens when air is being pushed outside of the vehicle. just keep a good clear area down to those vents. a good idea would be to use some ducting from the removable panel down to that vent in there so that passing moister doesn't soak into the poly filler.

BoomBoxB · 02-09-2009, 03:11 PM

Awesome i have 3 layers of fat mat on the rear hatch and there is still some rattle with the bass, hopefully that will help.
or take out the 4 12's ahahah

gravebox · 02-09-2009, 03:13 PM

^^actually, if it sounds like a license plate rattle, then adding filler wont help. you'll need to move the latch bar that the hatches latching mechanism latches to.

you'll need a T35 Torx tool, loosen the torx bolts and move the latch bar back by able 1-2mm. that will help with the rattle.

BoomBoxB · 02-09-2009, 03:16 PM

thanks, ill give that a try too.