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MikeyB
12-07-2005, 03:26 PM
Out of 3/4" MDF I have the plans for a SX 18" in a 6.5 cuft box tuned to 32 Hz. The dimension are as follows, please let me know if this looks right> 12in tall x 39 in wide x 31.25in deep. Which is 6.779 cubic feet, and the slot for this should be 10.5in tall x 2.5in wide x 5.15in deep. After taking away displacement for the slot and sub I have 6.51 cuft. Does this seem right, I checked my numbers and everything seems right accept maybe the slot. :eyebrow:

nissanrider06
12-07-2005, 03:29 PM
ur takin the internal dims?

MikeyB
12-07-2005, 05:53 PM
Those dimensions there are external

saywhat?
12-07-2005, 05:58 PM
u REALLY need more port area than 26.25 sq in.

saywhat?
12-07-2005, 06:08 PM
if u want 6.5 cubes, with 26.25 cubic inches of port, u will have 6.4 inches of port

MikeyB
12-07-2005, 06:57 PM
Here, this is the program I used. I didn't think that was right. >http://www.carstereo.com/help/Articles.cfm?id=31

Moe Lester
12-07-2005, 06:59 PM
That gives an accurate figure on how long the port should be. The problem with the enclosure is that you didnt give it enough port area.

MikeyB
12-07-2005, 07:00 PM
Yeah, my bad. I just recalculated it, I put the slot port dialog to yes before. Thanks Bro :cool:

MikeyB
12-07-2005, 07:01 PM
OOOOHHH, ya mind helping me out a bit. This is my first vented box :(

Moe Lester
12-07-2005, 07:03 PM
up it to ~90 sq in port.

MikeyB
12-07-2005, 07:04 PM
If I do that, then won't it be changing the tuning? I am so confused right now man lol sorry.

MikeyB
12-07-2005, 07:05 PM
OOOOOHHHH, I just started crunching some numbers. Let me work on this a minute and I'll post up what I come up with.

Moe Lester
12-07-2005, 07:06 PM
If I do that, then won't it be changing the tuning? I am so confused right now man lol sorry.

to keep the same tuning youll have to increase the port length. That will also make your box larger.

MikeyB
12-07-2005, 07:07 PM
How about this, 10.5in x 8in port that is 26.45in long?

Moe Lester
12-07-2005, 07:09 PM
if you can fit it that would be a great improvement :)

MikeyB
12-07-2005, 07:10 PM
Yeah I think it will fit, the box is 31.25in deep. BTW thanks a ton for your help man!

Moe Lester
12-07-2005, 07:11 PM
Yeah I think it will fit, the box is 31.25in deep. BTW thanks a ton for your help man!

just re-size the enclosure for the extra port displacement and youll be good to go :)

MikeyB
12-07-2005, 07:12 PM
This might sound better 10.5 x 8.75 which is 91.875 sq of port and 29.29in deep.

MikeyB
12-07-2005, 07:13 PM
Alright man cool Thanks again.

MikeyB
12-07-2005, 07:29 PM
Alright heres my new set of plans. 12 x 39 x 31.375 = 6.807 cuft

Port= 10.5 x 8.625 x 28.81 which is 90.5625 sq of port

After Port and Sub displacement I get 6.509 cuft

UUUUHHHH just realized I have to reconfigure that port again. 1 more try

MikeyB
12-07-2005, 08:01 PM
Alright I have 12 x 39 x 31.625= 6.864 cuft
Port= 10.5 x 8.625= 90.5 cuft or port and 28.81 of port length
All giving me a total of 6.513 cuft tuned to 32 Hz

saywhat?
12-07-2005, 08:06 PM
Alright I have 12 x 39 x 31.625= 6.864 cuft
Port= 10.5 x 8.625= 90.5 cuft or port and 28.81 of port length
All giving me a total of 6.513 cuft tuned to 32 Hz



if you go with 12x39x31.5 , internally that is 10.5x37.5x30. thats only. 6.8 cubes. im guessing your going to have to be around 5.5-6 cubes in reality to use those final specs.UNLESS u wanna spend the money on some aero ports. i can make u some plans. PM me for info.

MikeyB
12-07-2005, 09:10 PM
http://img190.imageshack.us/img190/5732/18boxbmp6pl.gif (http://imageshack.us)

How does this look?

Moe Lester
12-07-2005, 09:17 PM
well a port that size is going to displace almost 2 cubes judging by the dimensions of it. Your box volume would be reduced to something like 4.8.

[port height x width (including mdf) x length] / 1728

saywhat?
12-07-2005, 09:28 PM
thats what i told him in PM Moe. We can both help him by way of payment, but i'd be glad to teach him if thats his case.

MikeyB
12-08-2005, 05:56 PM
OHHHH before I was just taking away the MDF size, I didn't realize you had to include the port. Alright now I have 1.641 cuft of port area to take out. I see what you guys are saying. Thanks a ton guys. I'll work on it some more later tonight and make up another drawing. Yeah I kinda want to figure this all out so I know how to do it all in the future. I have made a lot of boxes in the past but never vented, just sealed. Thanks again guys!

MikeyB
12-08-2005, 11:15 PM
http://img276.imageshack.us/img276/1160/upportbmp7pr.jpg (http://imageshack.us)

http://img276.imageshack.us/img276/7583/upportbbmp8ai.jpg (http://imageshack.us)

Here is the new setup I just got done with. Should I make the port fire more like that or the original way?? Heres the specs

Box-12 x 39.75 x 38= 8.483
Vent-10 x 9 x 28.61=1.735 + .22 for driver=1.955
Total=6.528