HDC4 18 box ???

[Joe X]

It's actually a only a regular dodecagon, it's used because it very much approaches the characteristics of a round port but you can make it yourself the size you want, it's too much work IMO I guess if you are cornered and it's the only way to go about it might make sense.

[john253a]

I know what your saying

But that's dodecagon shape (10sides)

Look at dodecagon speaker boxes and the like

They yeald 10 speakers 1 on each side (well 9 normally the 10th is the stand)

I was assuming a 7" external port going into a

7" per side Dodecagon box with 9x 2.5" flared aero ports, (9 x 2.5" aero= 7")

So the box would have 18x 2.5" aero ports

With 2 going in every direction

Now that I think about it tunning wouldn't be that hard

Just efficiency would be way down

And the box would just look weird with 2 big disco looking balls coming from the top

[Joe X]

LOL. yes I have seen that kind of setup but not in cars and with speakers not subs.