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Trance is what I breathe
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Discussion Starter #1
Ok im not getting enough deep bass from my truck. How much polyfill should I add to my 2 12's? Should I just line the inside of my box with it or just throw some in there and call it a day? thanks
 

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Trance is what I breathe
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Discussion Starter #3
Port it? Ha there is not chance I can port my boxes. No where near the size to be ported
 

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Registered Slacker
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the u can still use the polyfill..
David taught me that usin polyfill in a sealed enclosure will make the sub think that it's in a bigger box..thus gain better sound..i think your bass can get lower too.. :D
 

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Project: Sabriel
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stuff it. polyfilling is good for ported boxes?
 

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Trance is what I breathe
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Discussion Starter #6
Yeah thats what I was thinking... ported and stuff it with polyfill got me confused....
 

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Trance is what I breathe
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Discussion Starter #7
so the box needs to be stuffed all the way.... ok Ill do that... I have my boxes in my room right now because im waiting for my battery to charge on my drill to get the subs out... I know im lazy... that and I was awaiting a response
 

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Trance is what I breathe
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926 Posts
Discussion Starter #8
Oh yeah another question... Can I put too much pollyfill in my boxes?
 

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Always Dreamin Big
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2,300 Posts
They should be stuffed lightly. The "ideal" amount is about 1.5 pounds of polyfill per cubic foot. The stuff is sold in bags marked in pounds, so it's pretty easy to figure out. Just don't pack it in there, that'll be too much. Whatever fits in loosly and easily.

Polyfill can be used in ported boxes. Almost all manufactures suggest some sort of damping material when running ported, usually a sheet or mat attached to the sides of the enclosure (simular to 1-2" thick home insulation, for a visual). I had nothing of the sort, so I very lightly stuffed my enclosure with polyfill. My sub and port are on opposite ends of the box, so I just put the material in the 2/3's that the sub is on. Seems to work fine. I did it on my old box with my JL 8 W-0 and it worked very well, seemed to lower the tuning a noticable amount, gave a stronger low end (I was very surprised, I was just trying it for kicks and grins).
 

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Trance is what I breathe
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Discussion Starter #10
Alright thanks alot for the quick response... I have the subs here laying in front of me and its getting late and I wanted to hurry and get it in before morning
 

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Always Dreamin Big
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SMNW2003 said:
I was told by a Memphis audio rep to stuff the box to the max, so that you had to push the sub down hard to screw it in
I've never heard that before. Seems by that point the volume of space occupied by the fibers themselves would severly effect the enclosure volume. Hell, to get it that tight you could easily fit 10+ pounds in a 1 ft^3 box, which is WAY too much. I had to make some elbow rest pads for a testing stand at college here. For padding I just grabbed some polyfill I had downstairs. The area I needed to fill was about the size of a fist full of the stuff. I had to pack about a dozen fistfulls into it to get the padding to provide a decent support.

Polyester synthetic fiber has a density of approximatly 100 pounds per cubic foot (if it were compressed into a solid, air-free block). So if you stuff 10 pounds in you just sucked 0.1 ft^3 out of the enclosure, and came no where near the "ideal" 15-20% enclosure volume "increase".



Tom Nuisane (spelling?) conducted a test a while back with the frequency responce of a woofer with different amounts of polyfill in the box. He did everything from no stuffing to (I think) 2 lbs per cubic foot. With about 1.5 pounds per cubic foot the enclosure perfromed as though it were 15% larger, and that was then the primo number. The test is somewhere online, but I cannot recall where.
 

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Always Dreamin Big
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2,300 Posts
SMNW2003 said:
or just build the box the right size to being with lol
JL Audio
Any standing waves that might be generated by upper ordered harmonics (caused by distortion) in the enclosure can be readily absorbed with the addition of damping material such as polyfill (available at your local cloth store--it is used to stuff pillows and quilts).
If you look many companies give their suggested box size and also have a note that it should be a 50% fill with polyfill, or that all sides should be lined with fiberfill, etc. I'd say in almost all cases a little polyfill is a good thing.
 

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Project: Sabriel
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hm...ill have to do that when i build my box. does it matter where the polyfill is - directly behind the subs, not blocking the port, ect ect?
 

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Trance is what I breathe
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Discussion Starter #17
I added some last night and it ended up sounded like total crap... I mean total crap... so I went back into my truck took the subs and boxes back out, took alot out and left some in there... Much better than before... Now im not so sure that the polyfill is any better than none... I have 2 sony xplode 12's that handle 200 watts rms... This is a temporary system till I get a job and get some Solo Barics. The demensions are... 22 x 16 x 8 The box really isnt even deep enough for the sub magnets so I had to get some half inch plywood and make a speaker ring spacer... Theres enough room for the subs to operate proper though
 

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Always Dreamin Big
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Is that box size per sub, or for the pair? I'm guessing that's each, because I don't see how you fit a pair of 12's in a 22" width. Is the box angled at all? I can't think of a Sony sub with over 6 inches of mounting depth, let alone 7.25+. Is the box leak free? How much did you stuff in there in the first place? If you had the subs in and out, is there a chance you switched up the polarity and first time and had them running out of phase?


If you are building a ported box you don't want the polyfill near the port. Really you don't want to use polyfill, a filler mat (like insulation) that can be attached to the inside walls of the enclosure is more ideal. You want to keep the stuff away from the voice coil vent as well. Insulating something that dissipates heat isn't a good idea. But basically just fluff it in there through out the box.
 

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Project: Sabriel
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would the peel 'n seal stuff be a good choice to line a ported box with?
 

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Always Dreamin Big
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Peel 'n seal? The stuff I know as peel n seal looks almost like electrical tape, can repair radiator hoses and such when out on the trail. It bonds to itself.

If you are talking something like a dampner similar to Dynamat, then no, I don't feel that would work well in a ported box. Dynamat works by lowering the resonant frequency of a steel surface, making sounds harder to pass through. MDF already has a very low resonant frequency and is good at damping vibrations (hit a piece of sheet metal with a hammer, then a piece of MDF). What the polyfill (or simular) does in a ported box is keeps waves from reflecting off the surface and out the port. Many people use egg-crate acoustical foam inside ported boxes, especially in home theater applications.
 
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