Subwoofer enclosure too small, need more airspace
 

I have a 10W6v2 in my passthrough, see pics. I recently came across a 10W7, and am replacing the 10W6v2 with it. My question is, I need .40ft3 more to put the box at the recommended JL Audio specs of 1.25ft3, before speaker disp. I was thinking of at the rear of the box at the bottom cut out a 4"X26" rectangle, and add a 5 sided box to it to make up the extra airspace I need. I have also heard that if I add a baffle or batting material that this will actually fool the sub into thinking that there is more airspace. What do you'll think. Will adding an (external box) to the original cause any side effects in sound, or as long as you have the internal volume you need regardless of shape be adequate.

generally, internal volume regardless of shape doesnt matter, but you would probably be better off just building a new box, adding on to an existing box can get kinda hairy. adding polyfill (commonly available at fabric stores) does fool the woofer into thinking it is in a larger box, but it really only is a bandaid.

I would try the polyfill first (it is really cheap) and see if that will satisfy your need, if that doesnt work, build a new box

The sub enclosure is as important as the sub itself. For one, the compliance of the subwoofer is designed to work with a certain amount of air assisting it in suspension of the cone. Two small the sub will become less efficient and will require more power to achieve the same excursion, to big and the subs peak power handling will be greatly reduced due to lack of adequate suspension. This is just one spec to illustrate how the sub is dependent upon the enclosure, there are many other reasons as well. Part of the reason the sub needs such a large box is because it has such a huge excursion.

In my opinion, why buy a top of the line sub and throw it is some box you had lying around. Chances are the w6 would sound better if it is in a box optimized for its requirements compared to a W7 in the wrong box. You can try it, but I would just build a new box.

You wanna sell that 10w6v2?

Thanks for all the input. I would build a new box, but the one I have in now actually was custom built. The front plate was molded from the passthrough. It ran me about $700.00 parts and labor. I could have another box built specifically for the W7, but the installer would probably do the same as me, and build it with a protrusion under the strut tower bar to get the extra .40ft3 I need. You can see that the strut tower bar is right up against the rear of the box. I may use the polyfill 1st, then if it's not what I expected I will add the extra airspace. I have designed it already, and thought it through how to attach it using liquid nails, some wooden dowls, and my small nail gun. I can use the nail gun from the inside of the box. I have chaulked lines on the inside where the nails should be place. Then use some wood screws on the outside to reinforce it. Maybe I will talk to a dealer and see what they think.
I was given the W7 in exchange for the W6V2, that is why I am wanting to use it. Also I am running a 1000/1 Slash amp so power is not an issue. My enclosure as it stands now measures .9399ft3. After the displacement of the W7 it will be .8499ft3. I just checked JL website they have a sealed range of 1.00-1.375 cu. ft. and a recommended of 1.25. These numbers are before speaker displacement. Darn almost there.

Well I did it! :D I replaced my JL 10W6V2 with a JL 10W7, and it was worth the hassle. It took me about 5 hours to build the add on enclosure. I took my time, and made sure I did it right. Here's a few pics. It sounds way better. just need to carpet the add on enclosure.