Math Gur's help with Sub Box Measurment
 

Ok guys here the question of the day?

I have a custom subwoofer box for my 2006z that is for a single 12 Subwoofer. The CF of the box is 1.5 ft^3, and a max mounting depth of 7.125. I need to shrink it down to 1 CF. I have plenty of space on the side of each back to ad pices of wood.

At the present momonet I have traced the inside of the left panel to insert a piece of wood with liguid nails to take up space. The measurement of the wood on all for sides are

Left = 9 Inches
Right = 5.5 Inches
Top = 8 Inches
Bottom = 5.5 Inches
Thickness of wood is 3/4 of an inch MDF. How the hell to I know how many pieces to cut and insert in my box to get it down to 1 CF?

You help would be greatly appreciated.

R,

Free

Well the easiest wood to use is lengths of 2x4. You can figure you need to fill up about .5 cubic foot, which would be approximately 875 cubic inches. 1 foot of 2x4 is about 75.5 cubic inches. So you will need about 11.58 feet of 2x4 to take up .5 cubic feet. These are approximates and i have also taken into account that 2x4's are not really 2"x4", but rather about 1.7"x3.7".

Then cut that 11.58 feet of 2x4 into pieces that will fit in your box and start gluing. remember to leave enough mounting depth for your sub.


EDIT!!!!
I just re-read your post, it sounds like you want to fill in the box with more 3/4" MDF? If so, we need the other dimension to the measurements you gave:
Left = 9 Inches x ???
Right = 5.5 Inches x ???
Top = 8 Inches x ???
Bottom = 5.5 Inches x ???

2 inches by 4 inches right not 2 feet x 4 feet?

Yes 2" x 4"......a wall stud.

Check your 3/4" MDF as most isn't 12/16" but sometimes 11/16th or something less than the expected 3/4".

Going by your dimensions of:

Left = 9 Inches
Right = 5.5 Inches
Top = 8 Inches
Bottom = 5.5 Inches
Thickness of wood is 3/4 of an inch MDF

I made a quick CAD model and got a volume for you. I assumed 11/16" MDF like Paul350Z suggested which comes out to a thickness of 0.057292 feet.


http://i21.photobucket.com/albums/b2...Fury/Area1.jpg


http://i21.photobucket.com/albums/b2...ry/Volume1.jpg



Based on these numbers you would need to cut out 28 of that exact shape of 3/4" MDF and glue them together (break them up into groups of 4 or 7 or something so you won't have 1 big MDF log) to add up to a total of 0.5 cubic feet. Glue all that stuff into a corner(s) of your box and that will give you a net volume of 1 cubic foot. This is a pretty ugly solution and if I were you I'd increase the size of that piece of wood. Then you won't have to cut out 28 of those shapes.

Ge|atinousFury

That awsome man but there is no way 28 of those will fit in the box becuase it would feel the whole box up! Maybe I not explaing the whole thing correctly then. The displacement of the speaker is .07, take that way formt he interior of 1.5 internal volume that leaves me with 1.43 internal CF.
So now I have to lose.43 internal in the box and so far I have managed to cut 6 sheets of the 3/4 inch particle board that I did measure and it was 3/4 right on the dot.

So where am I at now with a total of 8 slices, and can't use that foam spray at Lowes to get into the fibergalss curved part. This 12 inch box was made by a company in Orlando, Florida by the name of Exttreme Customs which was on Ebay but is not there anymore.

The internal volume of 1.5 ft^3, and a max mounting depth of 7.125 build with fiberglass and wood together.

This is all assuming the dimensions you gave me (and the computer shape I created) are correct....you better double-check your measurements and tell me if the dimensions are different for the shapes you're cutting out:

Volume per MDF slice = (Area)(Thickness) = (0.3074ft^2)(0.0626ft) = 0.0192125ft^3

You have 8 slices so far, so that's (8)(0.0192125ft^3) = 0.1537ft^3 that you have cut out in MDF

You need to displace 0.43ft^3 so you need 22 pieces total; (22)(0.0192125ft^3) = 0.422675ft^3

You have 14 more of them to cut out :)

Man, i must have read the original post wrong twice!!! now I see what those dimensions are of (thanks to Ge|atinousFury).

Ge|atinousFury has the answer. You will need to mount 11 slices of the MDF on each side.

Can you take a pic of the box?

Yes, but can some help me post it, becuase I have tried over two years!

I am going to take a picture now?

Here are the picture
 

Attachment 171315

Attachment 171316

Attachment 171317

Attachment 171318

Attachment 171319

As you can see 22 pieces will not allow me to put in the speaker!:icon11:

There are 4 slices on each side of the box already with a total of 8. I not going to get it to 1.0 but maybe get it to 1.25 taking in the .7 speaker dispalcement, I am not sure where I am at right now but I going to keep going. I plan on using spray foam in the corners from lowes.

OK, looks like you figured out how to upload pics......

I do see your dilemma. The bulging fiberglass front baffle is making it difficult. You could seal off both sides with fiberglass (the space between the front baffle and the wood slices you have added to the sides).

Side View Shot
 

Here is a side view shot. Maybe the sub will sound deeper and better with more space, crap I don't know at this point but we will see.

As you can see the sub faces upwards dropping the magnet towards the bottom so I can't go over too much more, probably 2 more sheets on each side.

I plan on going with the 13.0v ED, or until somebody advises me other wise.

You could add a piece or two to the top maybe? The 13Ov2 has a tolerance up to 1.25 cubic feet sealed. I think you should be pretty close to that as you have it.

Thanks street oc for all your help. Do you like the ED 13 subs?

What about spray foam, would that work or would that hurt the acoustics?

you could use it as a filler, but i would recommend covering it with fiberglass.

I see now, so much of that volume is encased by fiberglass and not MDF (as said by StreetOC102).

To be honest, I was having a hell of a time visualizing this box because it would take 5 feet of those MDF pieces stacked side by side to equal 1.5 cubic feet lmao....a picture says a thousand words!

And I agree, definitely don't use foam in a can unless you can cover it somehow to prevent little foam chips from getting all in your subwoofer

does fiber glass come in a can!

:icon18:

No, but they do sell the fiberglass mat and resin at home depot. You can get them for a total of maybe $25. it's not too hard to fiberglass when you aren't too worried about cosmetics, and since you would be doing it inside the enclosure cosmetics aren't a priority.