HELP NEEDED for port tube length-not for noobs

[saltyjesus 10+ year member]

I recieved two presents for christmas, a HUGE subwoofer box from my dad (that he custom made for two really bad radio shack subs), and two 12" rockford 8 ohm component subwoofers.

The box has two chambers, each being of approximately 4 ft^3.

Here are the subwoofer specs:

8 OHM single Voice Coil

FS (hz) 25

QTS .49

VAS0cu.ft. (liter) 6.10 (172.7)

Xmax-in.(mm) .302 (7.67)

SPL (dB @ 1w/1m) 89

RMS power 150

Peak power 400

they reccommend using a 2 cubic foot ported box with a port of 4"x10.75"

tuned to 35 Hz

My box is twice the cubic volume, so how what port tube should I use?

I really tried to figure this out, but I am not a math person and my dos software and 20 year old books didnt help. I really appreciate your help in advance.

Click to read more...

 

[saltyjesus 10+ year member]

and this is actually for my home audio system, if that helps.

 

[audiolife 5,000+ posts]

you plan on using a round port or a vent (rectangular)?

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

 

[saltyjesus 10+ year member]

round.

thanks for the link, im checkin it out now.

 

[saltyjesus 10+ year member]

that site did not take into account anything about the speaker.

is there a better port calculator out there?

 

[ANeonRider 10+ year member]

You don't need to use any t/s parameters. Port length and tuning is directly linked to box volume. That calculator is all you need.

 

[Nikuk 5,000+ posts]

I cant read

 

[audiolife 5,000+ posts]

id go 6" diameter i think the port length was 11.45??? or around that....with that it should rumble pretty good

 

[ANeonRider 10+ year member]

If it is being used in HT, I would go alot lower than 35 Hz. Personally, something around 23-25Hz //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[audiolife 5,000+ posts]

lol yuh i prolly would too but if i remember the old fosgates i dunno how well they would do that also dpends on the xover