I have a custom box that is .91 ft^3, and a sub that requires .625 ft^3. The sub is a JL 10w3v3. Should I plan to take up some of that volume by placing an appropriately sized wood block in the sub to take up some of the extra volume?

 

Yep.

 

yep, yep. Just be sure to fasten the board down (screws, etc.) so the board doesn't rattle or damage the JL sub

 

Thanks.

 

question: how do i measure the inside of a odd shaped sub box for volume? and do i subtract the woofer dimensions from the equation? thanks

 

is it a fiberglass box with contours? If its MDF, just use math, dont forget to subtract volume of the walls if you use external measurements.

 

Have you thought about a little expanding foam?

 

Messy, unpredictable and also foam.

 

its fiberglass top with mdf bottom, shaped funky to fit in the rear mid-well. i think i may have to use some form of filler to measure the inside but i just cant figure out what, and also, do i fill it to the rim or do i leave space for the woofer chassis?

 

Figure out the internal volume of the rectangular section, then figure out the volume of the section with the angled side and add them together. Be mindful of internal vs external dimensions.

 

Though rather larger than spec I would at least give it a try the way it is. Larger allows for lower end extension in most cases, if the sub will play lower at least. Smaller raises the lower end but increases power handling so if you have plenty of power it might play a bit louder.

You can fill up space by adding sections of 2x4, etc that you can measure and know what you are using up, they do need to be secured very well of course.

Rick

 

I measured my box volume by filling it with water and then poured this into a card board box with a plastic bag. Box was 1 cubic foot. Filled box and used a ruler to measure depth. 12 x 12 x what ever depth is divided by 1728 equals your box volume. This was more accurate than shipping peanuts but a little more messy.

 

Like Rick says, use a known factor. You will need a 2X4X94 (1.5X3.5X94) = 493.5 cubic inches or 0.285 cubic feet. 0.91-0.625=0.285
Of course this will have to be cut up to fit inside your box.
A 2 X 4 is actually 1.5 X 3.5 after it is finished and what is sold at your favorite lumber yard.

 

I used foam peanuts in mine to measure it. I filled a box that I knew the size of then took the peanuts and moved them over to the box, it isn't exact but I know my box is smaller than it really needs to be.

To the audio guys... how much bass Am i losing if my box is under sized by 25-30%

My audio guy sucks at getting back to me !

 

personally i dont mess with sealed boxes, they are for amatures! you would be better off going with a smaller sub and porting the box. youll get more output, it will play lower and it wont take up any more space. youll get nearly 2 times the output of a single sub of the same size.
also dont let the size of the sub fool you. it has NOTHING to do with how low it will play, ive made boxes out of (4) 6" drivers that were ported. it played every bit as loud and as low as a 15" sub
it's all about cone area, the more you have the louder it gets! and a correctly aligned / tuned ported enclosure will handel more power than sealed, provide tighter bass responce and have more output. the simple reason is that the port and the sub are in phase with each other at the tuned frequency, thus it effectivly uses audio energy that would otherwise be wasted in the box and uses that energy to create effectivly another speaker in the port itself.