Aero port recommendations

[TrakTuned]

I will be building a new box this weekend and I am thinking that I want to try my hand at some aero ports for the fact that I can adjust the tuning.

I am running an alpine type R 15 in a ~ 3.5cu.ft. box. Dimensions are 16tall x 20deep x 25wide. Sub and port firing into the cabin and I feel like it may be unloading a bit and not playing as well as it should. The port is 2x14x17 deep.

The new box should be sub up and I guess port toward cabin or rear? (Ford Probe hatchback)....Anyway I am thinking 15 x 22 x 25 this way th sub will be closer to the wall of the box, and hopefully pressure will build a little more before exiting the port?

I have the current box at around 34hz and would like a little higher tuning to match my music more, somewhere about 40hz I am thinking.

What size aero port should I use? Avoiding noise with a flared port would land me at ~40hz with 9in of port. With a 4in I would be running 3in?!?!?!? seems super short, wouldnt that also facilitate the "unloading" of pressure i am trying to avoid?

My sub also has little excursion leading me to believe my box has a lot of rise, and considering it should be seeing 1000wrms at 2ohms I dont see why it wouldnt be slappin.

I am a box building dummy, someone kick me down some help!

Edited May 19, 2012 by TrakTuned

[Joe X]

Your current box is low on port area but you should also take a look at your power and gains. Also you may want to know you are above Alpine's recommended net volume (2.25 cubic feet, 3.0 max), that usually can have a sub play louder the lows so you may want to shrink a bit the box for a more balanced response.

Anyways just to answer the question the following box will have proper port area, USE a flared port.

Enclosure Specifications:

Fb = 40.819 Hz

Vb = 2.971 ft^3

External Height = 15 in

External Width = 22 in

External Depth = 22 in

Cut Sheet List:

* All Dimensions in Inches.

* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:

Front & Back = 22 x 15

Left & Right Sides = 20 1/2 x 13 1/2

Top & Bottom = 22 x 20 1/2

Port Quantity and Dimensions:

Number of Ports = 1

Pipe Port Diameter = 6

Pipe Port Length = 11

Example of a 6" flared aero port:

http://www.parts-exp...tnumber=268-354

Edited May 19, 2012 by Joe X

[john253a]

box 16H x 25W x 20D in 3/4 with 3/4 baffle all around 3net

side ported 1 x 6" 18long 34hz

side or front ported 2 x 4" x 16long 33.5hz

side or front ported 1 x 6" x 14long 37hz

side or front ported 3 x 4" x 15long 42hz

side or front ported 3 x 4" x 12.5long 44hz

16x25x21

side ported 1 x 8" x 17long 45hz

youll be able to get more options with a removable slot port but the box will be harder to make

[john253a]

there are a few issues i see with box

first 15" high with a 15" sub doesn't work as the sub is always 15.xx" so you'll need to stay at 16"

secondly youll be overpowering it by 33% so idd stay under 3cuft net, as 3 in max recommended

third to use a 6" aero its close to 9" at flare so 15.xx +9" is 24.xx" width (you can put it lower of higher then the centre but the smallest box is 23.5" if you notch the flare on the aero)

hence idd go with slot ports

[TrakTuned]

Thanks for the reply guys!

I want the aero port for the fact that I would like to tune it as I like it..I have little experience and am unsure if I am going to like 40hz.

Secondly the sub will be on the TOP of the box firing up at the hatch. Should I also port to the hatch, or fire into the cabin?

For the height dimension, I will be needing to use 15 so the sub doesnt hit the hatch cover with excursion. ALSO ON THAT NOTE. Will it make it sound terrible not having enough room to load the sub on the hatch like 1" away????

[Joe X]

You need some airspace in front of the port (about it's diameter) for it to work properly so consider that.

[TrakTuned]

I am thinking dual 4" now....6" PVC is pretty hard to find.

So two 4" aero's at 10-11" each

Any benefit or disadvantage to this?

Edited May 20, 2012 by TrakTuned

[Joe X]

You don't reach 9 square inches per cube with the 2 4" on the box suggested above, maybe not a big deal, anyway I left you a link for a 6" on the design post if you are interested.

[TrakTuned]

Thanks for the link!

I can assume that is the general rule of thumb for proper port area, 9 square in. / cu.ft ?

[Joe X]

Right just a rule of thumb but give excellent results without needing to make use of more complicated methods.