Ported Box, Alpine Type R

[Qexler 10+ year member]

SWR-1243D Alpine type R 12"

Mrp-m500 alpine mono block (0 bass boost half gain set)

Roughly 1.3-1.5 Cubic feet sealed box.

Hey guys,

The problem I am having is adding a port to this woofers box, the sub is mounted inverted on account that the box is not deep enough for the woofer, it's a single cab ford ranger I have the sub in; so mounting it inverted allows it to set outward inbetween the bucket seats. I read on the12volt website that I could use this 1.3 sealed box rather than a 1.5 box and instead just make the ports length 18" long and then 4" around (pvc pipe for a round port) would be my choice. However I have had a really bad experience with my previous (ported) truck box and it blew A LOT of woofers. just wondering if this setup would work at all or is 12v is wrong?

EDIT: this was my exact ported box I previously used, its branded fierce audio so i was confused why it blew woofers.

http://images.craigslist.org/3n63k33mb5V35P65S5a7m28da9ac2863e1f6b.jpg

Click to read more...

 

[RAM_Designs 5,000+ posts]

I'd build a new box. 2.25ft^3 tuned to 33hz.

I'm confused as to how a ported box blew a lot of your woofers. Did they fry or just get ripped apart physically?

 

[Qexler 10+ year member]

The voice coils burned up almost instantly...

See I don't have 2.25 cubic feet room in my single cab ranger so i was looking at the 12v website reading that either 1.3 or 1.5 cubic feet box could have a 5 inch diameter round port (pvc pipe) and it could be 25.1 inches long to be tuned to 35 HZ? I don't mind some stupid long port... just love that air moving ported bass... But A large box just won't fit in my truck

EDIT: 1.5 cubic feet box!

30 inches long, 6 inches deep, 13 inches Tall.

 

[SpeedEuphoria 10+ year member]

Type R's like a large box

you prob best with a different sub that works better in your application.

Prob something smaller like a 10" ported that will be louder then your current 12"

 

[Qexler 10+ year member]

I'm just boggled why the12volt website tells me I can tune 35hz in a 1.5 cubic foot box, I was going to have the port completely out of the box 25" and with a 5" diameter. Wouldnt a bigger box just require a smaller or larger port?

 

[Buck 5,000+ posts]

You need a smaller sub //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Qexler 10+ year member]

So a 5 inch diameter round port in a 3 cubic feet box tuned to 30hz say needs to have a 15.9 inch long port...

where as if i wanted to tune my 1.5 cubic feet box to 30 hz it says i would use a 5 inch diameter port and have it 35 inches long... This would not work extending to port 20 inches? it practically adds to missing box size in the port itself right?

 

[Buck 5,000+ posts]

No. Ok, if you have the same diameter port, a smaller box needs a longer length than a larger box. The bigger the box, the shorter the port (with same port diameter).

 

[Buck 5,000+ posts]

The port does not count towards box volume.

 

[Qexler 10+ year member]

so the longer the port allows the sub to echo rather than just flop around in the box and move air? the extra long tunnel gives the sub trouble to push the air so it will make noise rather than a small port and small box it will just sound like wind correct?

thus a larger box and smaller port lets it echo because it has to move more of the box air.

So will a 1.5cb ft box absolutely not work with an extra long port?

it would sound the same wouldnt it, just with a super tacky port?

I don't care if it looks absolutely like crap, as long as its loud.

 

[Buck 5,000+ posts]

Eh, kind of not really. You just have to read around some, or ask specific questions.

 

[Qexler 10+ year member]

Specific question is, if I wanted my alpine type R (inverted mount) at 500rms alpine power to be ported in a 1.5 cb ft box.

Can I extend the port longer than it would be in a larger box to sacrifice from getting a bigger box and make the sub louder, and sound relatively as good as a larger ported box. tuned at pherhaps 35hz.

I thought it would work? just look like absolute crap having a tube sticking out of my box... figuring since it looked like that is why people didnt do it to a smaller box

 

[Buck 5,000+ posts]

Specific question is, if I wanted my alpine type R (inverted mount) at 500rms alpine power to be ported in a 1.5 cb ft box.Can I extend the port longer than it would be in a larger box to sacrifice from getting a bigger box and make the sub louder, and sound relatively as good as a larger ported box. tuned at pherhaps 35hz.

I thought it would work? just look like absolute crap having a tube sticking out of my box... figuring since it looked like that is why people didnt do it to a smaller box

No, subs need their airspace. Port length/size doesn't compensate for lack of airspace.

 

[Qexler 10+ year member]

Ok, so that calculator was just messing with me...

A box that is 2 cubic feet that would fit in my single cab ranger would be a massive pain...

 

[Qexler 10+ year member]

I thought 1.5 might be ok with the larger port because I believe Alpine reccomended 1.7 for there ported enclosures on a 12"?

Or actually it says...

0.8-1.5 ft3

External Box Dimensions 12.5" x 12.5" x 20.5"

Gross Internal Volume 1.4 ft3

Vent Area (dimensions) 11 in2 (11" x 1")

Vent Length 18.5"

Vent Displacement 0.24 ft3

Net Internal Volume (Vb)*** 1.1 ft3

F3, ripple, Fb 26Hz, 4.2dB, 35Hz