Ok, i have a question! when building a subwoofer box, does the shape of the box affect the sound of the subwoofer or does just the amount of air space required for each sub. i have built a few boxes that sounded pretty good, that stayed within the recommended air space, but where long and not to tall. would that have an effect on how the sub would sound or is the air space the only thing that matters! any help would be appreciated!

bigNAnative

 

It doesn't affect it very much. Just stay away from very long boxes (from rear of box to magnet). Try to use medium density fiber board, if available. I'll post Fosgate's link. They have a volume calculator that will help you get the air space right on. Here's a pic of my box I built. Specs== RF 3810's...5/8" mdf material....1.6 cu/ft air space/shared....ran in parallel/2 8ohm @ 4ohm load.....bridged mono


rockfordfosgate.com

 

To be overly generalizing...dont worry about box shape. Just stay away from cubes and brace properly. 3/4" MDF is the wood of preference although 5/8" is commonly used in trucks because of the lack of room. Airspace is the main factor. You can use polyfill or fiberglass insulation if you are forced to make the box a little under spec.

 

Cool, so i am good!

Another question i should ask is about polyfill! How much should i use if i can't build a box big enough! I have tried it with regular air spaced boxes but didn't really know how much to put in! I really didn't like the sound, but i figured it was becaus i put to much or to little in or it just didn't need it! are there any sites on the web that calculate that to! I found a site the helps you calculate a sub box cubic ft. its at: http://www.customcarsound.com/calc_box.html#box

I'll try this place and see what i can come up with!

thanks for the help!

bigNAnative

 

I always use a 1/2 rule with polyfil, fill the box 1/2 full and you'll be just fine, I also recommend using 3/4" instead of 5/8", I have done alot of testing with this and the 3/4" box was more accurate and didn't flex as much as the 5/8" box, the 3/4" box always measure higher SPL.

Also use a 2x2" brace where ever possible, I know in standard cab trucks space is hard to find and you hate to waste the internal volume with 3/4" wood and bracing but you'll notice the difference. I also "screw" the box together, and use "liguid nails" for all the joints and I also use it as a caulk when the box is together, I caulk every seem , HEAVILY!!! And also I never mount the subs(or sub) in the middle of the box, I always mounted them off to one side or another, unless you have two subs.

GOOD LUCK

 

What abbreviation is used in most sub manuals(manufacturers specs) for recommended box volume? Mine has two abbreviated words that make no sense to me. They only ones that look like a volume measurement are: Vas? .97ft[3] and SD 53.69in[2] I'm guessing that the box recommendation is the .97ft, am I right?,,,,98

 

Neither of those specs are the recommended box volume.

Vas is swept volume
Sd is cone area

 

Well, crap! ,,,,98

 

I finally broke down and called Polk today, and they said anything from .66 to 1.0 cu ft. will work. Is this a bigger is better sort of thing (for sealed enclosures). Is one end of the spectrum better for tighter bass, and the other for boomy? Should I try to build the biggest box that will fit? One thing I do know, is I need a new one I took a second look at my premade box today, and it has 1/2" thick walls. Probably not the best for a decent mid level 10" sub with 200 watts pumping through it.,,,,,98

 

1/2 " will work just fine...on your range of recommended air space, try to get on the high side. If you have to go low use about 1# of polyfill to 1cu.ft. of air space. don't forget your sub will subtract from your internal volume...i.e. the basket and magnet. That's what that volume calculator at fosgate will do...you enter all your max demensions and it will calculate the airspace. My box is as big as I can get it and still have original seat movement...I have around 1.6 cu.ft.

 

Your kidding on the 1/2", right? This is a "Wal-Mart" box we're talking about here. The black plastic plug with the connections on it shot out the first time I cranked it, lol,,,98