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bvr_j_0969
11-20-2006, 12:31 PM
like the title says could someone design me a ported box for 6 re 8's tuned to 30 hz?

its a truck wedge box i have all the deminsions i just cant find the port lengths

52" long, 10" bottom depth, 5" top depth, 21" tall i think the gross volume is 3.4 cft.

using 3 3" aero ports with flared ends. im not even sure i can get enough port volume with these ports for 6 ported?

subs specs .35 cft per sub ported subs displacement is .07 per sub.

i would like to use just 2 ports but not sure if i could get anywhere near the port volume i would need?

bvr_j_0969
11-20-2006, 12:35 PM
and i cant figure out the displacment for aero ports? if i could find the displacement of them i could figure the rest out

Big Dee
11-20-2006, 12:59 PM
It's easy you just subtract the flares and then calculate the volume of a cylinder.

bvr_j_0969
11-20-2006, 01:04 PM
It's easy you just subtract the flares and then calculate the volume of a cylinder.

but the flares take up displacement too? im trying to get this as acurate as possible, also i read in another thread searching, someone said the more ports the more spl?

Big Dee
11-20-2006, 01:11 PM
The inner flare doesn't count I think?

The outer flares would take up so little space I probably wouldn't even count them.

As far as port area I would just worry about having enough so that you eliminate port noise.

bvr_j_0969
11-20-2006, 01:16 PM
and im not sure on how much port area i would need for 6 re 8's also how much port area does 3 3" aero ports give me?

Big Dee
11-20-2006, 01:26 PM
and im not sure on how much port area i would need for 6 re 8's also how much port area does 3 3" aero ports give me?

I'll model them in WinISD and see what kind of port velocity they make.

Big Dee
11-20-2006, 01:32 PM
OK. I have them modeled, what frequency did you want it tuned to?

OneKrazyKeebler
11-20-2006, 01:32 PM
The flares count 1" more lengthwise than regular length per flare. I dunno if it would make a noticable difference if you did anything more than that.

bvr_j_0969
11-20-2006, 01:37 PM
30 hz

Big Dee
11-20-2006, 01:52 PM
OK for a 30 Hz tune you would need 3 3" ports 25" long each. The inner volume would take up .307 square feet. Although someone might want to double check my math.

bvr_j_0969
11-20-2006, 01:58 PM
according to every aero port calculator ive checked said somewhere between 19-20" port length but i dont know how accurate they are

Big Dee
11-20-2006, 02:05 PM
Aeros don't make any difference compared to regular tubes, you just have to add an inch or so.

I actually calculated it wrong, it should actually be about 28" for a NET volume of 2.1 cu ft.

edit. I read your post wrong, I thought you said you have .35 for every driver.

For your box they should be about 20-21", my bad.

dleccord
11-20-2006, 02:09 PM
why not use the one over at RE.com?

bvr_j_0969
11-20-2006, 02:10 PM
i havnt built the box yet but each driver needs .35 per sub plus .07 per sub for driver displacement

bvr_j_0969
11-20-2006, 02:10 PM
why not use the one over at RE.com?

it is slot port calculator isnt it? last time i checked i could only find a slot port calculator

bvr_j_0969
11-20-2006, 02:25 PM
would port placement make a big difference? i would like to have the ports on the top of the box but them needing to be 20-21" long that would put them within 1-1 3/4" from the bottom of the box which i think is to close?

so should i place the ports on the sides of the box porting into the cab corners or straight up towards the roof

Big Dee
11-20-2006, 02:30 PM
That 21" is not counting the flares, that would add at least an inch. That's not enough room to face them up.

bvr_j_0969
11-20-2006, 04:02 PM
That 21" is not counting the flares, that would add at least an inch. That's not enough room to face them up.

this has caused a problem, because only other place i could place the aero ports are on the sides of the box, porting them into the cab corners which my box is going to be so big that it will cover the whole cab corner opening, so it would be porting into a pretty much sealed area,

question is aero ports into the cab corners or slot port pointing up

j3bus2k3
11-20-2006, 04:08 PM
You need a vent's diameters spacing b/w the opening of the port to the opposing wall. If you cant do that, do a slot that comes out the bottom...

bvr_j_0969
11-20-2006, 04:09 PM
any pro's/cons from the top of the box and bottom?

j3bus2k3
11-20-2006, 04:11 PM
not really...you may feel the air coming out of the port onto your feet though. I'm going to crunch the numbers for ya for port length...something about dude's measurements don't sit right, probably cause I simply don't trust winISD.

j3bus2k3
11-20-2006, 04:15 PM
I cant tell you what optimal for the RE 8"s but I'll give you .35ft^3/driver since thats what you asked for...something in the .5-.75ft^3 per driver range may be better...

bvr_j_0969
11-20-2006, 04:16 PM
.35 is compact .5 is optimal but for 6 re 8's it is pushing the limits for airspace in my truck so i can only get 3.4 cubic feet gross box before any displacements

j3bus2k3
11-20-2006, 04:18 PM
uhh...not really...Your max dimensions gave me 4.740ft^3...

bvr_j_0969
11-20-2006, 04:21 PM
uhh...not really...Your max dimensions gave me 4.740ft^3...

uhhhm that isnt right
http://www.the12volt.com/caraudio/boxcalcs.asp

height 1- 10", height 2 -5", 52" wide, 21" tall

the truck wedge design

j3bus2k3
11-20-2006, 04:25 PM
For 6 RE8's at .5ft^3 each, each 3" port needs to be 20" long. Subtract the 5" that PSP inc requires gives you a 15" long tube. Glue on the flares and you've got your box at 3ft^3 tuned at 30hz...

j3bus2k3
11-20-2006, 04:27 PM
uhhhm that isnt right
http://www.the12volt.com/caraudio/boxcalcs.asp

height 1- 10", height 2 -5", 52" wide, 21" tall

the truck wedge design

Ahh...thickness...I thought you already took that into consideration when you gave them...

bvr_j_0969
11-20-2006, 04:28 PM
the way i have been trying to tune the box is find out the total cft of it then subtract the displacement of the drivers and then type that in on a port length calculator as cft volume of the box and then figure up the displacement of the port and subtract that from the total gross cft and the driver displacement and see if it leaves me enough airspace the drivers need is that the correct way?

bvr_j_0969
11-20-2006, 04:30 PM
nope sure didnt i had been relying on the calculators to take that into consideration, im off to work for now

j3bus2k3
11-20-2006, 04:31 PM
The way I've always done is it to take your net volume, and determine what you want to tune to. Find your port length and then with that, find your port displacment. Add your Net volume and port and driver displacement together which will give you your gross. Then from that, derive your dimensions...

Big Dee
11-20-2006, 04:41 PM
not really...you may feel the air coming out of the port onto your feet though. I'm going to crunch the numbers for ya for port length...something about dude's measurements don't sit right, probably cause I simply don't trust winISD.

I got the same result with 3 different calculators, please show me where my calculations were off.

j3bus2k3
11-20-2006, 04:45 PM
I just dont like those programs, I'd rather use pen and paper and the website of the ports maker...

j3bus2k3
11-20-2006, 04:49 PM
And again...for a 2.1ft^3 box at 30hz...each port needs to be 29" long; the tube itself needs to be 24". Which you cant do because the supplied tube is 17"

bvr_j_0969
11-20-2006, 10:53 PM
And again...for a 2.1ft^3 box at 30hz...each port needs to be 29" long; the tube itself needs to be 24". Which you cant do because the supplied tube is 17"

my box is going to be 3.4 cft before displacements, after driver displacements that would be 2.98 cft and thats what i have been trying to calculate my port length by

j3bus2k3
11-20-2006, 10:55 PM
2.98ft^3 net tuned at 30hz would need a port length of 20.11". If your using the flared ports from PSP Inc, you would need to cut the supplied tube to 15.11".

bvr_j_0969
11-20-2006, 11:03 PM
but the 20.11" poses a problem because to use the ports i would have to place the ports on the sides of the box pointing into the cab corners, which the box is going to more then likely seal off completely because it is going to be a very tight fit.

im not sure but i dont think it would be good to port a box into something that more then likely will be sealed up mostly

j3bus2k3
11-20-2006, 11:07 PM
No you dont smoosh (I know its not a word) the openings of the ports right against another surface. If you dont have a vents diameter of clearance, its not suggested...

j3bus2k3
11-20-2006, 11:10 PM
Just did a quick calculation and everything involved, Net volume, driver/port displacment, your standing at 3.229ft^3...