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View Full Version : decided to port my box, need some advice



substance
04-02-2003, 08:15 PM
i went to the store and got some 3 inch pvc pipe, a hacksaw to cut it, some caulk, and i got my dremel tool to make the hole, i just need someones advice on how long to make this port. The JL manual said to make it 12 inches, But to me this seems pretty long, especially since its not built to there specs. I was going to put the port on the far left side maybe have it sticking out an inch or so. The actual sub sits behind my console in my single cab silverado, the long left end of it sits behind the passenger seat. (i dont like the sub against my seat because it disorts the bass) Basically i took my car to stereo hut and they built me a box. This box is way too big to be sealed. I have a 10w3 in it, and i can only run it at 8 ohms, because the sub reaches its excursion at 2 ohms and makes loud popping noises at certain frequencys even with the gain and boost all the way down. I think this is due to the box being too big. I wanna go SPL with this. Im hooking it up to a EL 1500 bazooka 500watt 2ohms.
I would like to get this done tonight so i can let the caulk dry, so any suggestions would greatly help.. also, i am a newbie to building/reconstructing boxes, so pleas bear with me....

substance
04-02-2003, 08:16 PM
the side i want to put my port in

substance
04-02-2003, 08:17 PM
the pvc

ShaunMac
04-02-2003, 08:39 PM
First, you need to figure out how many cubic feet
your box is. Or put the dimensions of your box and
the thickness of the material used here so someone
can figure out the air space.

Then some of the box building guys here could give
you the correct length on the port for SPL.

substance
04-02-2003, 08:59 PM
width 32 1/2 inches, back hight is 10 3/4 inches, front (wedged) height From top to bottom 11 3/4 inches, top depth 4 1/2 inches bottom depth 9 1/2 inches, and the wood is 5/8 inch thick. i have no clue on figuring out the volume since this is a wedged box.

ShaunMac
04-02-2003, 09:34 PM
Well, I tried to figure the box out and came up with
right around 1 cu ft.
If that's right the 3" port at 12" long would give
you a tuning freq. around 37Hz. I think?

Does this drawing represent your dimensions correctly?

substance
04-02-2003, 09:58 PM
yes sir it is, in order to figure out my volume, do i add the two different heights together and divide them by 2 to figure the average height? and do the same thing for the depth? if so then depth = 7 inches, height 11.250 inches, and width 32.5 inches, therefore box volume = 1.4811

that is if my calculations are right, my math sux, but i did that on a calculator on this site http://www.carstereo.com/help/Articles.cfm?id=5 the bottom calc, then i used the volume and went here http://www.carstereo.com/help/Articles.cfm?id=31 and put my dimensions in, and it said that for 35 herts it would be 8.3 inches for my port. somehow this seems wrong. correct my math if its wrong.

ShaunMac
04-02-2003, 10:31 PM
You have to take into account the .625" thickness
of the wood.
It takes 1.25" off the width,height and depth.

Instead of 32.5" wide The internal width is 31.25"
This applies to all dimensions.

This makes the box smaller.

substance
04-02-2003, 10:35 PM
well while we figure out the volume imma go ahead and cut the hole on the side, its not gonna matter where i put the port right?

ShaunMac
04-02-2003, 10:48 PM
Just try to make sure you put it in the middle
as far away from the sides of the enclosure as
possible.

substance
04-03-2003, 01:51 AM
I made my port like 11.3 inches or so, and it sounds nice i didnt even caulk it yet, cause i had to jam it into the hole, like hammer it in there, so i dont think theres any air leaks.

well i guess its just time to get a new sub, i sounds great, but certain frequencys, like when the sub starts to hit a really hard note, the cone makes this loud popping sound that hurts my ears, does that mean the sub is damaged? even with the gain and boost down it will still do this, the only time it wont is when its wired at 8 ohms, but thats not loud enough for me. :( So i think imma get a sub that can handle a little more watts. I thought porting the box would help, but nope, but it certainly sounds better.

substance
04-04-2003, 11:44 AM
i put an audiobahn AW1006q in that box i ported and it bangs, louder than any of my freinds with 2 12s or 2 10s. I had to put a spacer in to make the sub fit in the box. I just got some liquid nails to attach the spacer..Im thinking about putting a bigger amp towards it. The subs rms is 900, and max at 1800. Im only putting 500 to it. It still sounds great though, But you know how bass IS ADDICTIVE and you want more and more.