PolyFill vs Egg Crate-Foam vs Fiberglass Insolation?

[rodH]

OK, In the planning stages of my DIY sealed sub. I am doing a 3 cu ft sealed enclosure. What is the best thing to use?

1. I HATE working with the fiberglass stuff

2. I ALSO need the box to be as BIG as it can (I understand that filling a LOT of polyfill will give this effect, how much do I need to get this effect, as I know that normally 1 pound is recommended for 1 cu ft.)?

3. I happen to have some of the egg foam stuff sitting around, but if isn't as good, I won't use it.


Any thoughts?

[Mike P.]

Polyfill is nornally what's used for your application. I believe the 1 pound per 1 cu. ft. is correct.

[mayhem13]

I use 1/2" carpet padding for the walls( it's cheap) and polyester pillow filling for stuffing-i'll buy cheap pillows and cut em open. Works great as far as i can tell.

[Warmon]

rodH wrote:

I ALSO need the box to be as BIG as it can (I understand that filling a LOT of polyfill will give this effect, how much do I need to get this effect, as I know that normally 1 pound is recommended for 1 cu ft.)?

If you need the box to be big, then model it Q=.577. If this gives you the size you're after, you don't want to stuff it, but you do want to line it. Crate foam will work for this. Be aware that this does make your f3 point slightly higher, but you'll get a little more on the low end - a flatter curve.

[rodH]

what does Q=.577??

people earlier were telling me to heavy fill with the polyfill to make the enclosure seem larger than it really it?

No I am really confused ??

[Warmon]

rodH wrote:

No I am really confused ??

You're putting two torrents in a single box, right? You said you want the box to be big, right? Do you mean you want the box to BE BIG or SEEM BIG? In your first post, you said BE...as in physical size. Where did you come up with 3 cf - What Qtc does that represent?

How do you even know you want it big or seem big? Size [Vb] is dictated by the type of response you want or need. Here's a concise write up to get you up to speed.

[rodH]

thanks, I will have to read that.

People were originally saying I should use something larger than the 3.0 cu ft for optimal performance. The PE box I was planning on getting, was going to cost over $70 in shipping, so I am no longer limited to its dimensions. Now it looks like I might beable to make it a little larger, like 3.5 to 4.0 since I will have the enclosure made custom now. So now it really isn't as big of a deal as it was before.

[Warmon]

Okay, now I see where we got off track.

Usually the best thing to do is to use Qtc=.707 to get Vb and then stuff with fill at 1-1.5lbs per cf. You can remove or add to get what sounds best. If you don't want to learn all the ins and out of WinISD, Unibox or others, you can use the java script calculator on the same site to get Vb.

This will give you a good overview on the whole stuffing issue.

[Exocer]

I've tried all of those stated in the title of this thread, plus sonic barrier.

i've settled on two small "blobs" of polyfill behind each midrange driver in the rear of each. In this particular situation, egg crate foam seemed to be more of a nuisance as it never wanted to stay in its place...

I use a combination of thick egg crate foam and polyfill for my sealed sub. It took quite a while to get a result that sounded "subjectively" better than just using one or the other.

My advice would be to stay away from the fiber glass if you dont like working with it...polyfill will do the same job(at a higher cost).

Experiment a little...