Stuffing enclosures

[Kevin M]

Polyfill works, so does egg crate foam but they work for two different reasons. You can use it in ported enclosures, it just needs to be stapled to the interior wall. There needs to be a clear path or transition for the air to travel through. I have 8 pieces of 2 1/4" egg crate foam in my wall.

Looking through port...

Rear wall of the wall lol

It could be a placebo effect but I definitely felt I was louder over the same freq. range with it than without. (25-60hz) Better attack and decay. Now that it is ported the foam is still inside. If your ported enclosure is on the small side you can use poly to help but from what I have seen it tends to lower the tuning freq. 3-10hz from what I have read. Some HT cats throw whole pillows in their enclosures which contain the polyfill. lol There is also diminishing returns when you try to stuff more than 1 lb. per cu. feet regardless of the alignment the drivers in. Sadly, no one has done any experiments so most of my info is anecdotal just based on what I have read and firsthand experience. Here is an interesting article on the subject...

This information was taken from an article by Tom Nousaine, Car Stereo Review, March/April '95

It's no secret that you can use fiberfill to make low-end magic; clever installers have

been using it for years. Take two boxes of the same size and type, insert the same

woofer into each one, and stuff one with some fiberfill. The one with the stuffing should

kick out lower bass.

In simple terms, it works like this: The fiberfill fools the woofer into thinking that it's in a larger box (one with more air, or internal volume) than it really is. And, in general, the larger the box, the lower the bass you can get out of it.

Fiberfill stuffing is a popular alternative for people who can't or don't want to allow a lot of

space for a subwoofer box.

The particulars of fiber stuffing are pretty interesting: The air inside your enclosure

actually heats up as your woofer moves, making the air stiffer. When the enclosure is stuffed with fiber, the fibers wiggle, dissipating some of the heat and making the system work as though the box were larger. Theoretically, your

woofer/box bass system can act like a system that's a maximum of 40 percent larger

when you've latched onto the right stuffing recipe – in other words, if you have an

enclosure that offers 1 cubic foot (1 ft³ ) of internal volume, in a perfect world a good

stuffing job will make it perform like an enclosure that offers 1.4 cubic feet of internal

volume.

There are three types of stuffing that are commonly used for this purpose: fiberglass

insulation, long-fiber wool, and polyester fiberfill. Fiberfill is the best choice because it doesn't come loose and fly around and irritate your skin or lungs like fiberglass, it works as well as either of the others, it's a lot cheaper than wool, and moths hate it. I recently bought five 20-ounce bags of it at $1.99 a pop (a total of 6.26 pounds for $9.95) at

Minnesota Fabrics; that turns out to be about $1.60 a pound. You should be able to find

some at any fabric store or in the bedding section at friendly stores like K-Mart or Home

Depot.

To evaluate the effectiveness of box stuffing, I used an MLSSA analyzer to measure the

impedance of three enclosures – 5.l-cubic-foot sealed, 1.4-cubic-foot sealed, and

1.4-cubic-foot ported (the port measured 3 inches in diameter and 6 inches in length) –

with various densities of stuffing. For the sealed boxes, I was able to determine the

effective box size – as enhanced by the stuffing – using the system's resonant-frequency

and Qes values. For the ported box, I compared the tuned frequency of the empty

enclosure to the tuned frequency of the stuffed enclosure, using the Speak for Windows

computer program; this enabled me to find the effective box size that fit the actual

resonant frequency I'd measured.

In each case, the news was good – make that very good. With all three boxes, I enjoyed

roughly 25 to 35 percent of "space gain" by using stuffing at a rate of 1 to 1.75 pounds

per cubic foot of internal volume.

When making system performance predictions, be aware that the Qes figure – and,

therefore, the Qts figure – of the sealed boxes dropped. And with the ported box, the

peak of the impedance curve on the lower side of the tuned frequency became heavily damped below the box's point of resonance. I also found that there is such a thing as too much of a good thing: System resonance (Fsb) rises again, beginning with densities of around 1.5 pounds of stuffing per cubic foot of box volume; this happens because the fibers are jammed so tightly together that they stop wiggling and, consequently, stop dissipating heat.

I also found that stuffing gets less effective as box size increases. The morale: The

bigger your box is, the harder it is to fool your woofer.

A few rules of thumb: Stuff small enclosures – those with up to about 3 cubic feet of

internal volume or less – with 1.5 pounds of fiberfill for each cubic foot of internal volume

and you should get about a 30-percent increase in box volume without seriously affecting

other performance variables. For larger enclosures, add stuffing at a rate of

approximately 1 pound per cubic foot and you should get a virtual-space boost of about

25 percent.

[RooTxBeeR]

Holy shit Kevin! Should have put a disclamer up, WALL OF TEXT! lol, Seen the pics the bam! Good shit though, never knew you put that in your box!

Edit: Wall of txt disclaimer, GOOOD READ!!!!

Edited May 27, 2012 by RooTxBeeR

[Kevin M]

Holy shit Kevin! Should have put a disclamer up, WALL OF TEXT! lol, Seen the pics the bam! Good shit though, never knew you put that in your box!

Edit: Wall of txt disclaimer, GOOOD READ!!!!

hahaha Thx bro. It's a long read but worth it if you want to get a better idea on it's applications The foam has only been in there for about 3-4 weeks. It wasn't in when you heard it. You'll need to get another demo.

Edited May 27, 2012 by TheScottishBear

[RooTxBeeR]

Ahhhhh, are those pics up in the build log>?

[Kevin M]

Ahhhhh, are those pics up in the build log>?

I went out this morning and took them. I just put the cam in side the port

[RooTxBeeR]

Ohhhh good shit, was about to say, I never seen those pics before

[Riley Evan Houser]

I've had 12"s big guy.. But those deep notes the 15"s hit are my thing

12's can hit deep notes big guy

No.. I know they can. I mean..i just love the different sound the 15"s put out

[CLNFREAK]

my personal experance:

i did a sealed box in a miata ... added poly fill and it made a world of difference freq response was much better then the empty box

shallow mount 6.5" kicker on a 200 watts or so

[AB18VFL]

I've had 12"s big guy.. But those deep notes the 15"s hit are my thing

dont fucking call me out no0b, you have no clue what youre talking about. dont come here for advice and try and be a fucking toughguy when you get the advice you dont wanna hear.

[Riley Evan Houser]

I've had 12"s big guy.. But those deep notes the 15"s hit are my thing

dont fucking call me out no0b, you have no clue what youre talking about. dont come here for advice and try and be a fucking toughguy when you get the advice you dont wanna hear.

Woah there, calm down man. I was just simply saying that I've had 12"s and I've had 15"s and I just prefer the sounds coming from 15"s over 12"s. No need to get defensive, everyone is titled to an opinion. But, sorry if you felt that I "called you out?" Not sure where you got that one.. Was just saying what I prefer. Also, that had absolutely nothing to do with hearing advice that I didn't want to hear. That's why I'm here, is for advice.. I'm very thankful for all the advice I have been given and I even appreciated that you were spreading your opinion to me about 12"s.