Port Design Help...

[AcIdBuRn02ZTS]

Hey guys...

getting ready to start a new build and have a couple of questions...

Planning on running 2 RE Audio SX 18s in ~14cu.ft and am wanting to port it at ~30hz... maybe lower

On that note... I dont understand the required port area... On some of the calculators Ive seen... its suggesting a minimum port area of 202sq.in, so does that mean just the opening?

would it be better to go with a larger port area? I wanted to use round ports for how my box is designed (subs firing up, ports firing back) but dont know if I can get the required port area using round ports...

If going round... its saying I would need 3 10" ports to get the area I need... and port length would have to be over 30" which is too long for my box design...

Even on a slot style port... port length has to be really long (30+") to get down to 30hz... Is the box just too small or what am I missing?

Thanks for any help.

-Chris

[AcIdBuRn02ZTS]

Any suggestions guys?

[AcIdBuRn02ZTS]

How about port area?

I'm using 2 RE Audio SX 18s w/ an xmax of 22mm

Need to know a good port area... is 200^2in correct? I'm using a 14^3ft box (net) and at 14^2in per cube... thats right at 196^2in.

I want it to sound good overall but move a lot of air... would this be right?

30hz is what im shooting for... is that low enough?

I'll be pushing em' w/ 2krms for the time being and will be moving up to 3-4krms in the near future..

Please help

Thanks

-Chris

[-Hobby-]

you can use anywhere between 170 sq in and 220 sq in of port for a 14 cube net box. Lower tuning means a longer port and a larger box (gross). I havent messed with RE subs but staying between 12 sq in per cube and 16 sq in per cube is a good general rule to stick to. I couldnt give you a length for your port without a proper design. Different sizes and port wall configurations change the length. You just need to determine your max dimensions you want to work within and configure the box till it meets your specs.

[fecupe2001]

Just remember something Acid, if you want 14 cubic feet then you need bigger box then, that big ass port, subs and any other displacement are gonna take some internal space from your box.

Anyways, i would start with around 18 cubic feet, a 196 SQ of port (14 SQ of port per cubic feet) would work very nice, port needs to be around 28" deep so you can have a 30 hz tuning and around 14 cubic feet after displacement

[AcIdBuRn02ZTS]

Just remember something Acid, if you want 14 cubic feet then you need bigger box then, that big ass port, subs and any other displacement are gonna take some internal space from your box.

Anyways, i would start with around 18 cubic feet, a 196 SQ of port (14 SQ of port per cubic feet) would work very nice, port needs to be around 28" deep so you can have a 30 hz tuning and around 14 cubic feet after displacement

Gross internal volume of the box will be around 18.3^3ft.

Outer Dimensions - 49w x 22h x 34d

I'm debating on using round or square port... I'm looking around on the forums at other's designs and builds and see what looks best... then building accordingly

Would 28" deep be far enough away from the rear most wall of the box to be effective since Ive only got 34" of depth or would I have to bend the port?

Could I go external with part of the port? My amp rack will be built onto the rear of the box... so I could come out of the box 4" and work it into the design nicely... or do external ports do the same thing? ( I would think they do... but Ive only built one ported box and I want this to be done right the first time)

Thanks guys

-Chris

-EDIT-

On a side note... think this will be enough box/sub/power to have anykind of hairtrick out of the tahoe or will I not be moving enough air? Its quite a bit of space... so I didnt know.

Edited December 10, 2010 by AcIdBuRn02ZTS

[fecupe2001]

I saw this is a tahoe, so i guess it´s a no wall box in the trunk maybe? 49" wide seems kind of big for a trunk but i don´t know much about your truck, yes you can use AEROPORTS wich take way less internal space,i would build this:

Box: 22" x 45" x 34" with 1" MDF wood, double baffle of course

3 8" aeroports 20" deep each one, that should murder

[AcIdBuRn02ZTS]

Well... the box is being built as easily removeable...

No wall... the truck has 2nd row buckets and a 3rd row seat that is removed... box will be directly behind the 2nd row seats... 22"h with subs firing up... 34" back will allow me to use the factory cargo tie downs as anchor points for the box yet keeping it easily removeable... and ports firing to the rear.

49" is the total width I have to work with in the rear and I prefer to keep the box fairly snug...

Using 3 8" ports would only give me 150.7^2 inches of port area... is that enough? I'm sure you know a bit more about this then I do... I'm just wondering why everything ive read is saying somewhere near 195-200^2 in. of port is needed

Thanks again for the help

-Chris

[-Hobby-]

For round ports thats plenty. You dont need as much port area for a round port.

[fecupe2001]

This forum is for people to learn my friend, it´s all cool, ask whatever question you got in your mind, i´m not a big expert but i do have a some experience

Anyways, YES, what people have recommended you it´s good on the SLOT PORT area, aeroports are more efficient and need less area to work properly, if you Slot need to be between 12-16 SQ per cubic feet, aeros need 8-12 SQ per cubic feet, remember that´s just a general daily rule, but still works great! Said that, yes 3 8" aeroports are almost 151 SQ of port giving you around 10.5 SQ of port per cubic feet after displacement, should work great!!

I have 11.5 cubic feet and 4 6" PVC tubes and im doing some major hairtricks hehe