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liljojo4711
11-19-2008, 03:46 PM
http://i33.tinypic.com/snl8jm.jpg
http://i35.tinypic.com/1y0ryt.jpg

that is my box. i want to have 2 aero ports tuned to 35hz. what size ports do i need and how long should each one be?

9seconlives
11-20-2008, 02:21 AM
Depending on the sub going in there then check the specs and if it calls for a 3"x6" port then just cut the length in half and keep the diameter the same....run 2x3"x3" ports (this is just an example though) also i would put the ports on the outside edge of the box as far away from the sub as possible...but that's just me. i heard once that for every 1/2" of port =1htz depending on if your addding to or taking away from the port.

Rashaddd
11-20-2008, 02:41 AM
that box looks familiar

mcsoul
11-20-2008, 09:48 AM
If you wanted the ports in those locations, they would have to
be 2.5" wide and 8.25" deep each. I used 2.25 cubic feet as my
estimate of your gross box displacement, and 2.1 after woofer
displacement. That would get you close, but it does not look like
you have the mounting depth needed. The internal end of the port
needs to be 3" from the back wall.

2" ports would only have to be 5" long, but that is not enough port area.
It's close though.

liljojo4711
11-20-2008, 05:48 PM
so what would be ur suggestions? with 2 2" ports that are 5" long, what would my tuning be?

liljojo4711
11-20-2008, 05:48 PM
that box looks familiar

yeah thanks a lot ;)

Rashaddd
11-20-2008, 11:45 PM
so what would be ur suggestions? with 2 2" ports that are 5" long, what would my tuning be?

I didn't check, but considering he said they need to be 5" long I'm assuming he was checking how long at 35hz

SPLEclipse
11-21-2008, 12:32 AM
assuming those are outside dementions and you are using .75" material to build it, i got this:

net box volume: 2.222 ft^3
port area (with two 3" vents): 14.137 in^2
port length: 12.414"
net box volume: 2.12 ft^3
port tuning: 35hz

also...you can't cut the length for one 3" vent in half for two 3" ports. you have to look at overall port area and calculate the length for each port accordingly. in this case you would have two (2) 3" ports each with 12.414" of length. also, subtracting/adding .5" of port does not increase/deacrease the tuning by 1hz. port tuning isnt a linear function.

with one 3" diameter vent, you would only need 4.81" of length. your port area would be 7.069 in^2. that "should" be OK assuming it's an aeroport. thats really driver/power dependant though.

liljojo4711
11-22-2008, 12:52 PM
well my box is only 12" deep so there is no way i can have a port that is 12.414" long... so i should go with 1 3" port that is 4.81" long? what if i want two ports, would i need 2 2" ports or something?

also, i will be adding bracing and my sub displacement is .14 so wont that change the tuning frequency? i want to get the box down to around 1.8-1.9 cu ft after all displacement and bracing...

SPLEclipse
11-22-2008, 01:44 PM
at 1.85 ft^3 gross (after all driver/bracing displacement but before port displacement), you will need 6.274" of length with a 3" round port. your net volume will be 1.824 ft^3. the tuning is at 35hz. also (something i forgot to mention earlier), www.psp-inc.com always adds and inch to port length measurments for flared designs. im not sure why but you should check out that site for sure. thier port lengths for non-flared designs are off a little though.

liljojo4711
11-22-2008, 03:21 PM
i will get a flared port. so i should just get one 3" port? is there any way i can use say 2 2" ports?

according to that site i can do 2 2" ports that are 7.01" long. that sound correct?

SPL Blazer
11-22-2008, 03:27 PM
Precision ports website is dead on with the flared port numbers, I've always used it and tested after and it was always right.

SPL Blazer
11-22-2008, 03:33 PM
And you need to leave room between the port opening and the inside walls, meaning with a 3" port you need to leave at least 3" of space all around the port opening, 4" with the 4" port etc.

bonesninja
11-22-2008, 03:43 PM
Depending on the sub going in there then check the specs and if it calls for a 3"x6" port then just cut the length in half and keep the diameter the same....run 2x3"x3" ports (this is just an example though) also i would put the ports on the outside edge of the box as far away from the sub as possible...but that's just me. i heard once that for every 1/2" of port =1htz depending on if your addding to or taking away from the port.

wow....you sir are uneducated in this topic

SPLEclipse
11-22-2008, 06:31 PM
for (2) two inch ports i get 6.062" length on each (again, with 1.85ft^3 of airspace after sub and bracing displacement @ 35hz). that would mean 7.062" with flared ports...so you should be fine with that.

also, i dont think the psp calculator takes into account the volume of the port in relation to the box when it gives you a length. either way though...its very, very close and should only be a 1hz difference or so at most, lol.

liljojo4711
11-23-2008, 11:33 AM
ok. does anyone think that i will not have room for these ports considering the angles of the sides of the box? im also a little worried about the sub fitting in with the extreme angle of the top of the box... anyone maybe see a problem with these?