Basic Process for Building a 8" sub for the Cubby on the right (facing car from rear)

I'm posting this now, as its something I've been wanting to give back to the community, but its taking me ages to finish it.

Disclaimer: This is still a project in motion and have not tested the resulting sound. I have disobeyed all the laws of enclosure building due to the nature of the space. I work in millimeters....

So here goes.....

I crudley cut pieces of 6mm cardboard into the shapes that seemed to fit each side and then taped them together to get the basic fit. I then took measurements and cut new pieces of cardboard and built a mockup to test the accuracy of the model.

The height was not an issue to start with as I was more interested to get the tightest fit to maximise the enclosure size. Once I had the mockup built, I had to cut the height down and make minor adjustments to the sides to be able to get it into the cubby. For this you have to remove the side carpet.

Once I had the mockup fitting to my liking, I measured all the sides and drew a cutting plan. There are some weird angles and the only way to get them is to fit the matching sides.

I orignally intended to use 12mm MDF, but seeing as all the rules of enclosure building have to be forgotton due to space and shape issues, I decided to build the first box with 6mm MDF.

Basically, another mockup. It it works, cool, if not, I would have a better set of measurements to build a box with thicker sides.

Using 6mm MDF its also easier to get the sides to fit with the weird angles as its slighly flexible.

Once the cutting plan was set, I marked it off, and cut all the pieces. There is one corner on the bottom that is almost 90 degrees. I started assembling from there. I used wood glue and small nails.

You have to assemble the whole thing except for the top in one go and use all 4 hands before the glue dries, as you have to nail and force some of the sides to fit in the weird angles.

I did shave the edges at about a 5 degree angle to get a flusher fit.

Once all the sides where up, and used good amounts of wood glue on the inside of the joins to seal and strenthen the joins. Once dry, I filled any funny bits with wood filler and sanded.

Once built, I tested the fit and it fitted like a glove. I had to trim the top a bit so that it fitted under the flap (I don't want to cut the flap off), but I expected that. I traced the top piece from the finished box and an 8" circle just fits.

The whole process took me a weekend with enough time to mess about with other stuff while the glue drying and stuff.


Still to do:
I need to buy an 8" woofer.
I need to find a small amp and find a suitable place to put it as my car battery uses the other cubby.
I plan to upgrade the other four speakers once I figure the amp thing out. I might even use the radio's built-in amp for the four speakers and put the amp inside the sub (active Sub ).
Once I have the Sub Driver, measure and cut the hole.
Paint the enclosure mat black.

Once its all done, if the 6mm box is not rigid enough, I might fit 'braces' inside. But I'm hoping it should be OK. I'm not looking for audiophile quailty, just rounding off the sound.

Maybe someone will finish this before me and post the results. I plan to get my act together next month... and will extend this thread with that stuff.


I'll do some measuring tonight and post the numbers tomorrow for each other sides.

Here are some of the pics....

 

Vey nicely done. Do you have any pic of it in the car? I'm hoping to do something like this in the future.

 

Here are measurements. Unfortunately for you guys, I work in millimeters. I pretty sure a tolerance of a 2-3mm shouldn't make a difference.

I need to redraw the scale folded-out plan better and will post it here when done.
So for now the sides and letter marks relate to the photo with the pieces cut.

As a memtioned earlier, there is not top yet, but you can cut your own once the box is built.

Side 1 (S1)
B 215mm
C 195mm
H 212mm
I 210mm

Side 2 (S2)
D 220mm
E 228mm
G 225mm
k 270mm

Side 3 (S3)
A 223mm
B 215mm
D 220mm
J 328mm

Side 4 (S4)
F 227mm
G 228mm
H 212mm
L 343mm

Bottom (B)
A 223mm
C 195mm
E 228mm
F 227mm

Also... these measurments are the outer dimesions. You will need to subtract the material width from the sides depending if it is inner or outer joined.

One more thing... power tools..... don't try this will with a pair of scissors and a nailfile.

 

I've only got as far as the pics show, but I'll take a pic of it in the cuby tomorrow.

I plan to finally finish the project next month and will post more...

 

I was thinking to get a plastic bag, and some foam injection milding stuff.. and fill the whole space with the foam.. and take it out when it hardens.. Then i can just build my model around this for optimum fit. Whats every one think about this idea..

Also, could i use ur messurments for the drivers side if i flip them around some how? I want to put one one each side

Thx- Keith (Mikes Brother)

 

Dude... you rock.

 

I think you will have a block of foam stuck in your wheel well.

 

no it will be in a plastic bag.. so it wont get stuck in the wheel well.. like a thick garbage bag.. then i shave it down into a box, and build my box aroundn that mold.. maybe even out of fiberglass so i get curves so it fits perfectly

 

Its not a bad ideal, but you'll have to find a sub that will match the amount of cubic air inside of this foam enclosure. Its the most common thing overlook when making a box, a sub needs a specific amount of air to sound right.

 

i asume that the sub you buy will have this amount on it, in cubic something or other? or is it a standard number that is determined by speak size/wattage/ ect

 

Each speaker will normally come with a set of published "Thiele-Small Parameters" which define the electrical and mechanical characteristics of the driver. You design the enclosure based on these specifications. http://editweb.iglou.com/eminence/em...s02/params.htm

-David

 

I plan to use the Rockford Fosgate 8" driver. According to the spec I need an enclosure of 0.25 Cubic ft for a sealed box.

If do really rough calculations, the my box comes to about 0.40 Cubic feet. I'm going to get a precise volume measurement this weekend. If its too big, I'll simple chop off the height a bit to get as close as possible.

Although... chopping of the height makes the top smaller and it might not fit the 8" driver.... maybe fill the bottom or something...

 

OK.. just done the mearument using elementary physics and a lot of water..... 12.75 Liters or 0.45 cubic feet. Wow... I was pleasantly surprised, it doesn't look that big....

I guess there is space to use thicker walls.

 

Don't build a whole new box... you can cut pieces to fit inside your present enclosure and glue them to the walls. You can also fit a brace or two to further reduce cabinet resonance.

Looks good!

 

Good Stuff...... I was just about to do this.



So with the volume you obtained using a thicker MDF is no problem. Perfect.