ZAPCO VEGA

FYI
that box design will work awesome but I didnt look at it closely i would use a 1/4 SD of the driver for port opening if possible minimum for the most output. I used a box similar design to that at World Finals and it did the trick.

98_Z24

iTrader: (3)

Anychance you can explain that a bit to me, I've got no clue what an SD is

ZAPCO VEGA

Sd = speaker displacement
it should be in your thiele small parameters or in the specification sheet that comes with subwoofer. For example if your SD of your driver was 150 square inches a good number to stay with for port area would be 37.5 square inches. Your port area is 16 x 3 which is 48 square inches a nice size just depends if your going for spl it is good if your going for SQ I would go with a smaller port. Just a reccomendation.

For instance a JL Audio 12w3 has 80.06 sd so a 20 square inch port like 10" x 2"by whatever deep for tuning would reccomended.

rorybreaker

good box, but be very careful when putting an elbow in your port (the 90 degree curve). At all costs you want to maintain the exact same cross sectional area that the air is resonating in, at the elbow a lot of wierd turbulance can impede velocity leading to lacluster pressure at the port mouth.

As for your original question round vs slot? slot wins every time. The component that kills port efficiency is turbulance as the air rushes out of the port into the listening environment. Basically more edge length per port area is better. A circle is the minimum curcumfrence per area, so it's kinda the worst.

as for the aeroport product I have limited enthusiasm. Run a router around your properly measured port and you eliminate a lot of turbulance, but if you measure the actual tuned FB of your finished product you notice you've essentially built a port shorter than you planned or a box tuned higher than you planned. There's a fundamental changeover when the air mass expands leaving the port that is now occurring at the start of the flare of the port. I've always run a router around my port openings, but I've also run 5-10 test ports to find one that results in the proper tuned FB I'm attempting.

This box should work well for you as long as you make acurate cuts and measurements on a table saw, but if you're using a chainsaw make a port with no bends in it. Essentially a ported speaker box is an electronic component running the port by way of resonence. The port geometry is just as important as the speaker.

98_Z24

iTrader: (3)

To Zapco Vega, SD of my Mmats is .15 cu feet. And yes, I'm looking for the best SPL I can get out of a 3 cubic ft box (That's all the room I have, but I believe that's the max reccomendded for the speaker anyway.) Rory, not sure what you're saying about the elbow part of the port... do you mean rounding off it's edges to create less distirbance of airflow, such as this:

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Instead of:

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(Best I can do with a keypad lol) EDIT: Never came out as it should, but I'm talking about rounding the edges of the 90 degree part...

zzzzzzz

iTrader: (5)

why can i not see the pic?

rorybreaker

By "elbow" I mean where your port turns 90 degrees inside the box. It's extremely important that the corners inside the port section are crisp and straight. You want it to be a perfect smooth edge right up to the corner, and then a perfect 90 degree turn. No spot at all where theres ridges that you try to fill in or sand out, the cross sectional area of the port has to remain constant.
Basically you want it to look perfect, use a table saw and be super acurate if possible. I usually prefer to test ports tuned to several frequencies near my original "calculated goal" to see which works best. With a port such as this one you're stuck with the first result, so you want to make sure everything's as perfect as possible.

ZAPCO VEGA

the speaker displacement is the total amount of cubic feet your subwoofer will take up in the sub box I am a little rusty been a few years since I came on here. what i meant was the total piston surface area. Effective Piston Area (Sd). Which i just went and visited the Mmats website and it is not listed at all.

to elaborate on what rory breaker is saying look at your pic above in my post you need to make sure the port remains consistently at whatever your width of the port is all the way through so you dont have problems.

well I will try to make a pic
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no matter how hard i tryi t wont let me draw it

rorybreaker

yeah, what he said.
This is a fully functional design, and your original image is correct. I've seen a lot of boxes with this style of port being mass manufactured lately, but I'm kinda cautious about it because the rule of thumb is to maintain a perfect cross sectional area throughout the length of the port. If your port doesn't ring true with a conventional straight-in port you can modify it easily. With this design you're stuck with it (build a new box).

If you used box software to come up with this design and you trust the parameters you've got for your speaker go for it. Aw hell, go for it anyways and tell us how it turns out.

ZAPCO VEGA

yeah go for it it is only 25 dollars worth of mdf. Just dont end up with a bill of 10000 dollars for mdf like i did and just keep building new sub boxes like crazy.