abysil

iTrader: (1)

I'm looking to build a box for two DD1010's. I had originally decided to build a fenderbox fitted to the side of my trunk, one in each side, but then i realized that would be a lot of work to actually measure out. Trunk kinda has some weird angles/cutout thingies going on, and have to leave clearance for moving parts of trunk lid etc. So I thought i'd start simple and figure out the basics, then try to go on and build this kickass fender box.

So, DD's website suggests 1.2 to 1.5cu. ft. for a 10" sub. They also say assume 16" slot port, where surface area cross-section is 15-16" for every cubic foot of volume. So the first question that comes to mind is:
does the volume of air /in/ the port count towards total internal volume? AKA would you count the 16"x16" (volume of a port for a 1cu. ft. box) towards the volume of 1cu. ft.?

Anyways, so i attached an image of a sketch i whipped up, figuring out some dimensions that could work. i came up with 12"(height inside, add 1.5" for the 3/4MDF to get external... = 13.5" outside), 15" from front to inside of back wall, (15.75 external, the 15" takes the port right up to the front of the box), 2" port, and 13" from left wall to inside of inside port wall (whoa, wordy). so that would give 17.25" (i wrote 16.5, but i missed the 0.75" of the MDF for the port) external along the front.

I drew this up at 1am last night, so miscalculated some of the measurements. They should be correct in above paragraph though.

The second diagram, I retardedly forgot that i decided it should be 15" deep, so the dimensions for length of inside wall of port are wrong. Should replace 14.5 with 13", and 13.75 with 12.25". Makes more sense. Also makes for a 15.75" port, if you count 14" to midpoint of corner, then 1.75" from midpoint of corner to inside of box. Port end is also imprecise, as the one side (back of the box) is still existent, so add margin of error. In any case, that was a very overly lengthy description of the port.

So far what have i done wrong? This is first time blueprinting a box, so let me know what I have to fix (if anything).

Complete internal volume of box as it stands is:
port - 15"x24" (length x cross section = volume), add 0.75x24" (for that little bit at the end of the port, where port wall ends... this really should be negligible) = 378cu"
inside of box - 13"x14.25"x12" (width, depth, height) = 2223cu".
total internal volume = 2601cu" / 1728cu"/cu.ft. = 1.50 cu.ft.

So, 1.5cuft without sub in it. DD suggests estimate sub will displace 0.1cu.ft, leaving it at 1.4cu.ft., then whatever bracing I put in... so probably around 1.35cuft final.

So here's the question. That is a plausible design for one of the two 1010's. For a second one, could i just place it beside, invert the blueprint, and have them connected with just the 3/4" MDF in between? They'd share the base, top, face and back of the box. Subs would either be in towards the centre with ports on the far side, or they would be out towards the ouside with ports in the centre.. Suggestions?

Sorry that that had to be so tedious and long..........
Any help or pointers would be appreciated.
Thanks!
-Mike

PS - Aimed towards SQ rather than SPL.

Jo-Psyko

iTrader: (1)

ok your math is right, as long as the number dd says to use is gross internal volume and yes build two then just flip one over and put a long top/bottom on to connect them its up to you weather the ports be on the outside or side by side in the middle

abysil

iTrader: (1)

General Box Design
and
Motor Design

"All volumes listed are after vent, and subwoofer displacement"
What do you think 'after vent' means? Does that mean the volume of the inside of the box (so for mine 13"x14.25x12")? Or including port as i did?

Net volume. So i'm guestimating 1.35 for those dimensions. As such, though, the port is designed for what they have listed as 1.5cu.ft. Big difference? or dont worry about it?
-Mike

abysil

iTrader: (1)

So I'm still not quite sure if the volume of air /inside/ the port counts towards the 1.5cu.ft. If it does, that box is golden. If not, I have to redesign a little bit, which I think i will do anyways.
New scenario. Since my car has a ski-hole in the back seat, I put the two subs as a V firing into the hole, and have the two ports going up to where the rear speakers used to be. Shouldn't be too difficult to build... if i knew whether or not port volume counts towards specified vol.
Heh.
-Mike

liv2ride

iTrader: (1)

This is just my opinion, but if you have the subs firing V into the cabin by the ski hole, the bass will almost cancel itself out. I tried this setup before, the best bass response is when you have the subs firing the trunk lid (back of the car)..

if your seat folds down, then thats a different story, but my car has a ski hole, and the seats do not fold down and i've tried it facing the back seat, its a no go for bass.. crazy cancellation !

abysil

iTrader: (1)

Could wire one of them backwards, put them out of phase. Other option, build box suchthat subs are facing up towards where the rear speakers came out of and build ports towards ski-hole. So like described above, but they're not in a V anymore. Still using ski-hole and speaker holes for either sub or port, just the other way around.
-Mike
PS. Like the phase idea or switch location better?

liv2ride

iTrader: (1)

Yea that would work.. I thought about that many times, but my rear deck is not even manageable at all, its got too many waves etc. You have the right Idea abysil, can't wait to see what you do !