round port question

[jblayz1 10+ year member]

i'm thinking of making a ported box 2 cu. @ 31 hz here are the dimensions i'm thinking.

width- 17"

depth- 19"

height- 16.5"

without a port i figured the cu. is 2.348

what i can't figure out is the dimensions i would need a round 4" port to be in order to tune it to 30-32 hz. i'm thinking side port, maybe... and the sub facing rear. i tried it calculating a square port, no dice. can't get it to tune low enough.

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[jblayz1 10+ year member]

or i could do two 2" ports but i don't know what length they need to be...

 

[mazdakid 5,000+ posts]

2 4"

the 2 2" wont be enough

a single 4" probably wont be either but around 14" long would be 31hz

 

[jblayz1 10+ year member]

how about two 4" round, 7" long ports facing the cab and the sub facing the rear ? would that make this enclosure 2 cu. @ 31hz ?

 

[Immacomputer 10+ year member]

how about two 4" round, 7" long ports facing the cab and the sub facing the rear ? would that make this enclosure 2 cu. @ 31hz ?

No. You doubled the amount of port area which means you need to increase the lengths.

If you do 2 4" ports, you would need to make them 31.5" long EACH. I don't see that happening in your enclosure unless they're external.

 

[jblayz1 10+ year member]

**** it. backwards numbers again. seems to happen often in car audio.

ok, so would i need to do one or two ports and what sizes?

 

[Immacomputer 10+ year member]

What sub and what kind of power?

 

[jblayz1 10+ year member]

12" tc3k hybrid and re 12.1 1200@1 ohm. i could do it this way too. but the enclosure is humungus..LOL.