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View Full Version : port help.. again.. take a glance at this!



rickymac21
01-17-2009, 02:07 AM
quick questions.. im building a 14.5 cubic ft box for my 18s... i had some 5"pvc layin around that i just flared to use as aeroports.. only had enough for 4 ports though... that only equals like 75 sq inch of port area... everyone has been tellin me 4 6" aeros would be enough for my box of 2 18's... anyways if i add in 2 more 4" aeros thatll be more than the 4 6" aeros would.... only thing i want to know is if i can actually do this without problems,,?? and if so, how do i tune the 4" ports to the same frequency as the 5" ports????

Rashaddd
01-17-2009, 03:32 AM
no, dont.

rickymac21
01-17-2009, 11:50 AM
no, dont.

haha. alright man. thanks. thats all i needed..

Rashaddd
01-17-2009, 01:00 PM
haha. alright man. thanks. thats all i needed..

actually, after rethinking it, I can't think of a reason it wouldn't work. Port area is port area, and the mass of air in the ports doesn't care whether one port has more area than the other.

think of it this way. You have a slot port. You put a divider down the center of it, to split it in half...does the sound change now that you have two smaller ports instead of one big one? No. Great, so what if you had that divider off center by 5 or 6 inches (so that you're not splitting it 50/50, maybe 30/70 for example)? Would the sound somehow be altered? Just because a separator is in a different spot? Did it really change anything about the air in the ports? No, it's the same thing.

Just make sure you are accounting for total port area, and then make all ports the same length.

jdawg
01-17-2009, 01:27 PM
i would just use the 5's, you got pics? how did you flare it? or did you just round it over?

dcole18
01-17-2009, 01:30 PM
the problem would be figuring out the tuning... you would have to figure out total port area and then calcualte length

rickymac21
01-17-2009, 01:39 PM
the problem would be figuring out the tuning... you would have to figure out total port area and then calcualte length

yea, that was my biggest concern... i wasnt sure how exactly i would tune the other 2 4" ports the same as the 5" ports.. but i went ahead and changed my mind to useing 10 4" ports, seeing how i have a 10' tube of 4" pvc. lol... im actually planning on makeing the box 14.5 cu ft. so each port is gonna be 12.5" long ( including flare ) tuning me at 40 hertz for spl... then for every day ill cover 2 of the ports and that will bring me down to 36 hertz, and still have enough port area...

and as for makeing the flares, i did it kinda ghetto but it works for the most part... i bought a heat gun and the pvc. and you just heat the end of the pvc where your flaring it.. then once it gets flexable i would bend it with a wrench type deal. you keep doing it till it cools off and starts to get hard and thats when it starts to stay in place... after than i sand it down really good to make it smooth. it takes time because you have to make sure its all leveled. but it sure is cheaper than buying all them aeroports!!!

Slim_Shady
01-17-2009, 01:45 PM
Like rashadd said.

Find out total port area of all ports.
Figure out a formula to convert that to a single port...like...say 4 6" ports and a 4 is equal to a 13 inch port or something along those lines....
Maybe you can figure out total port area, find the square root and divide by pi and see if that works? It's something like that..

Slim_Shady
01-17-2009, 01:51 PM
Try this.
Find total port area
Divide by pi
Find square root.
That should equal the radius of a single port w/ that area.
Radius x 2 should be the diameter you use to calculate length of port
Maybe :crap:

Rashaddd
01-17-2009, 02:25 PM
^

that is correct

mcsoul
01-17-2009, 02:57 PM
I would use all same radii ports.

rickymac21
01-17-2009, 03:24 PM
I would use all same radii ports.

yea.. I am.. im just sticking with the 4" ports since i already have the pvc to make them...