building box for tacoma truck

[93civEJ1 10+ year member]

ok...I started building a box for a tacoma truck. I will be using 2 8" subs that sound and perform best at around .7-.75 cu ft on a vented box. So I am guessing 1 big box that will house 2 speakers at around 1.5 cu ft would suffice for 2 8's that require that...correct?

I calculated the box to be actually around 1.9, but still have a couple things to factor in such as speaker volume and a small brace etc that will take up volume as well.

Now....the question I have is on ports. On a dual sub setup that shares the same air space...what is the best way to go about porting this? I dont have much room for long ports, so is there a min or max number of ports one should install to get the required tuning frequency, or does number of ports matter? I know diameter and length play a part...just wondering if there is a certain number of ports u should have per speakers, etc.

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[ngsm13 5,000+ posts]

Ideally, you need to design your box (including port size, area, tuning) before construction. The tuning of a ported box is based on: box volume, port area, tuning, and also length (knowing the first three, gets you the fourth). The problem in your situation comes from volume. Already having a restricted volume, adding a port will further change your net volume.

In your situation, I would recommend a 4" aeroport. It would be the easiest to implement and allows you to easily change the length (leading to a change in tuning). Can you even fit a 4" aeroport is the next question? As to get a desirable tuning it will probably need to be fairly long.

 

[93civEJ1 10+ year member]

Why does it seem that on the calculators the smaller diameter ports needs shorter lengths to get the desired tuning frequency

 

[ngsm13 5,000+ posts]

Why does it seem that on the calculators the smaller diameter ports needs shorter lengths to get the desired tuning frequency

It doesn't seem that way, it IS that way. haha.

Given a set volume and tuning, port length varies based on the cross-sectional area of the port. Larger port, means longer length for desired tuned. Smaller port, shorter length.

 

[93civEJ1 10+ year member]

It doesn't seem that way, it IS that way. haha.
Given a set volume and tuning, port length varies based on the cross-sectional area of the port. Larger port, means longer length for desired tuned. Smaller port, shorter length.

whats the downside to smaller diameter ports then? I dont really have the space to do long ports due to not much depth to the box due to it being a truck box.......the max dept is the bottom of the box is 8.5" deep. Top is even smaller due to seat angle.

 

[ngsm13 5,000+ posts]

Less port area, mean more port noise, too small and you restrict the airflow.

How wide is it? Port it out the side.

 

[93civEJ1 10+ year member]

this is the box soo far, so you can see the depth is not very deep......the 8's will be on each end of the box in the deeper area.

 

[ngsm13 5,000+ posts]

this is the box soo far, so you can see the depth is not very deep......the 8's will be on each end of the box in the deeper area.

Well made box.

That said, I would not port that enclosure. With the way the top space is heavily restricted, and the leg jutting out in the bottom middle...it will most likely cause weird response. Personally I would seal off the bottom half below the channel horizontal channel and make it a sealed box. Just my thoughts on the subject.

 

[93civEJ1 10+ year member]

What if I were to place the 2 eights on the far side of the box (its plenty big enough) and use the other side to port...if I came out the side with the port in the section below the channel, I would have plenty of room for port length.

 

[93civEJ1 10+ year member]

like so:

 

[ngsm13 5,000+ posts]

If I had to, that is the way I would do it. Still will cause interference IMO...

 

[KyleBechtold 5,000+ posts]

like so:

is that runner down the middle where the box will stop? if so that little channel between the left leg jutting out and the middle will kill it..

 

[93civEJ1 10+ year member]

i found someone on here who built a slotted vent :

Would that be better

 

[KyleBechtold 5,000+ posts]

honestly the only way I could see that still working would be if you did a zig zag port not aero and it worked in length to the leg.. other wise that whole side is wasted with the port opening in the channel..

 

[93civEJ1 10+ year member]

is that runner down the middle where the box will stop? if so that little channel between the left leg jutting out and the middle will kill it..

no the channel that goes from side to side is just to clear a section of the cab of the truck...the upper area is more air space.