AngHellicTc

Here's the plan I followed:



I placed the sub on top of the box instead of on front like shown in the pic. I hooked up the sub, and turned it on, and I didn't even know that having that much port noise was possible. It sounds like a gust of wind every time the sub hits.

My sub is a 12" Fi Q. They recommend up to 2.5 cu ft ported at 32hz, with 12 to 16 sq in of port area per cu ft.

That box measured out to 2.6 cu ft, prior to sub displacement, tuned to 32hz.

I have no clue why there is so much port noise, I rounded off the sharp edges a little bit even with a sander. Anyone have any ideas on how to fix it?

blazeplacid

ran the numbers on the measurements you gave

Im getting 3.4 cubes tuned to ~27hz.....

http://www.the12volt.com/caraudio/boxcalcs.asp

same height and depth but 28" wide would be 2.5 cubes before displacements

Superman05

LMFAO!!!! Sorry but I don't know why that title is so funny to me. I ran the #'s and that box is bigger then u thought....by about 1 cube. Try again my young padawan!

Vask

In order to tune that size port correctly, it would need to be drastically shorter, so short in fact that it would create a free air resonance box. Most ports following that design are for show. I suggest order ng 4x 4" dia port tubes, cut them at 10" lengths, and put them in the box facing upwards with the sub.
That sub has a very large excursion and displaces a large air volume. That port style is very turbulent.

AngHellicTc

wtf 3.4 cubes?? ugh that makes me angry. just spent way too much time for this damn box..

deathbyc4

welcome to the world of fluid dynamics

AngHellicTc

Sooo those dimensions actually are correct.. Had it been a sealed box, it'd be 3.27 cu ft. But once you take out the volume of the port and wood inside the box, it'd be 2.68 cu ft.

The only thing wrong I notice, is that the port length isn't fully correct. With the length it is at, it is closer to 31hz tuning.

So all in all, after sub displacement, I will have a 2.52 cu ft box, tuned to 31hz, with 12.4 sq in of port area per cu ft of volume (with sub displacement out). It seems like everything worked out after all..

I'm gonna stick the sub in the box tomorrow, and as for the port, If i stick an angled piece of wood in the corner of the port, would that fix the port noise? or at least reduce the turbulence?

Vask

To reduce turbulence on that style of port, fillet or chamfer all of the edges (especially the bounding wall on the inside of the box)
The easiest way to do this would be to get some rounded wall molding and tack/glue it into the corners and that end piece.

AngHellicTc

Got the box built the correct way today. Sounds amazin. So much better sound out of it than my last 1.8 cu ft box. Just gotta retune the amp and carpet it. I will probably hit up the inside of the port too to reduce any little turbulence, but I can barely hear any port noise.

Vask

Nice.