Is there a way to know how much poly fill one would need to bring a boxes cubic feet into spec? I have a box design that is 0.939 ft3 that needs to be .70 ft3. I have the box designed to fit in the car around other things. The only other option I can think of it to shorten the box and make a stand so it sits at the correct height above the other components of the system.
Any help would be great
poly fill is to make the sub think theres more airspace than there really is. with the magnet volume you may be alright on airspace. check the paperwork on the sub and see what volume the sub fills.
-------------
According to the paper work it wants .70ft3. I "think" I need to reduce from 0.939ft3 down to the .70ft3 for the best response. I could be wrong. The last speakers I used had a box that was with in .04ft3 of the spec sheet and they hit hard! I want to get these new ones to hit like the old ones did.
As ss said, leave the polyfil out because you'll be going in the opposite direction using it. This is a sealed box, I presume? There are a couple ways you can look at it: oftentimes a slightly larger volume than required by manufacturer is not only okay but can make the sub's low extension better; or, it's much easier to make a big box smaller than it is to make a small box bigger. You can use solid fill, like a piece of 2 X 4 framing lumber, to take up a portion of the cubic feet in the enclosure. And as ss said, make sure you know the manufacturer's intentions of NET volume....did they already include the displacement of the driver with those specs? If not, you need to add driver displacement and any other volumes of displacement to the intended net result to arrive at the overall inside volume you should have.
And, sealed designs are very forgiving over a wide range of volumes. My hunch (and not knowing all the particulars) is that you will get good results with the volume you described.
-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Is the design for SQ or SPL?
If you are running the subwoofer with a moderate amount of power and would like better transient response and better low frequency roll off then keep it at .939!
That said, .2ft^3 isn't going to make much difference.
-------------
New Project: 2003 Pathfinder
Thanks guys. I am just got really worried when I was done with the 3d design and found the volume to be bigger that intended. I am not sure if the net volume that is given includes the subwoofer removed or not. I am going to assume that it is and go with the design as is.
I am trying to get the most spac out of the Hatch of a 80's mustang. Really tight in there! I took into concideration that I will want to get to my spare and add a second battery in the near future! I also wanted some space to store tools, jumper cables, and my skates!
I have 3d design pics if anyone is intrested and would like to use the design on thier mustang!
Again,
Thanks Alot!!