# Speaker box design help



## newfi (Dec 25, 2011)

Hey there I trying to design a box to go in the back of a 96 ford ranger extended cab. I'm wanting it to sit on the little 6" curb to utilize the floor space for cargo and passengers legs. I also want to be able to use the rear fold down jumper seats which leaves me with about 16" in between them in the center. The highest I want to go is 21" which is at the lower edge of the rear slider window. The sub I'm using is the JBL GTO804. I want it to have the .6 cf (it's what's recommended). With a slot port tuned to 33 hz. I want the speaker front firing and the slot on top pointing up. I have come up with some box dimensions but I want to be sure I'm on the right track. Anyone have any suggestions or criticism??


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## Sonnie (Apr 11, 2006)

For that small of a box you should have plenty of room. Have you checked out our enclosure calculator?


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## newfi (Dec 25, 2011)

Thanks for the link I haven't found it yet on the mobile app version. Ya I've been using the calculators. I've been hoping someone here has some experience with these subs


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## newfi (Dec 25, 2011)

I'm also having trouble with slot port tuning. Trying to figure out slot size with min area of 10 square inches but tuned down to 33hz just doesn't seem like it's going to happen. Like the length has to be awfully long


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## Sonnie (Apr 11, 2006)

Likely not here, but have you tried diymobileaudio.com?


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## newfi (Dec 25, 2011)

Not yet but I will thanks Sonnie


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## Mike P. (Apr 6, 2007)

You are correct, it won't work. With your box dimensions the port will take up 513 cubic inches leaving you with a net volume of .34 cu.ft.


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## newfi (Dec 25, 2011)

But if I go smaller than 10square inches of area then I will encounter port noise correct


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## Mike P. (Apr 6, 2007)

What amp will you use and does it have a subsonic filter?


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## newfi (Dec 25, 2011)

By the way mike. How did you figure that so fast. I have been working on this for a while now. Maybe you can help me design a box hint hint


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## newfi (Dec 25, 2011)

I was going to start with an old punch 150 because that's what I have right now. But I can upgrade later


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## Mike P. (Apr 6, 2007)

I've been running the numbers, the driver can handle 200 watts with a subsonic filter at 25 hz. The recommended port with 10 inches of port area is smaller than a 4" round port. Going any smaller to get the net volume up will run the risk of port noise.


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## Sonnie (Apr 11, 2006)

newfi said:


> By the way mike. How did you figure that so fast. I have been working on this for a while now. Maybe you can help me design a box hint hint


I think he cheats myself.


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## newfi (Dec 25, 2011)

No subsonic filter on this amp. Old punch 150a2
I think I see what you saying though. So in other words to avoid port noise I need to stay around the target number 10sf. But to tune it that low I would then have to add about .28 cf to get back to .6 cf


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## Mike P. (Apr 6, 2007)

Yes, you could probably get away with a .5 cu.ft. net volume.


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## newfi (Dec 25, 2011)

I guess that would be easier. A lot shorter in length. You think that .1cf smaller in size would be very noticeable? I could expand my box in width somewhat


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## Mike P. (Apr 6, 2007)

If you can go bigger than go bigger. Best to keep to the recommended box size and tuning if you can.


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## newfi (Dec 25, 2011)

Well the recommended size for ported is .6cf but also tuned at 40hz. I figured I could go lower if I wanted to


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## newfi (Dec 25, 2011)

What's the thinnest mdf that you would use. I'm not sure if I should go any thinner than 3/4"


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## Mike P. (Apr 6, 2007)

A 40 hz tuning would make the port shorter and take up a bit less cabinet volume. 3/4" material is minimum in my opinion.


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## MetropolisLake (Sep 22, 2014)

Not sure if this helps but one old school trick for these situations when any extra space is a blessing is to actually build the box onto the back of your cab. The rippled metal behind the seats is the back of your sub box. Basically you place a panel up against the metal then use a compass to trace the ripples, then cut it out with a jigsaw. Use those for your top and bottom. Basically just build a box with no back with these rippled panels, then screw the whole thing on. Put DynaMat on the metal, possibly screw a brace or two on, seal it up with silicone. I've built one of these in a Ford Ranger before.


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