Sub/ Port /output question

[DFW40 10+ year member]

Many of these slotted ports are very large like: 2 inches by 12 inches. This has an area or 24 inches. This is roughly the same area as a 5.5 inch round pvc port.

As the port diameter gets larger the longer the port needs to be to maintain the same tuning of the enclosure.

My question is do larger ports produce a louder output than smaller ports, I would assume yes. So would a 5 inch round port really offer that much more output than a 3 inch port etc? Where does the law of diminishing returns come into play?

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[I want SExxx 10+ year member]

Yes the more port area you have the louder the output. Why do you think the ports in SPL vehicles are so HUGE? However the bigger the port the looser and more out of control the bass will sound... so while most poeple find a happy medium like you example I port the HELL out of my boxes and cross them over low and let my midbass do all the "punching" and higher bass notes while my sub(s) are/is killing it down low. My current port area for 2 sexxx12's is about 75 inches.

 

[powerslide 10+ year member]

Your port has to be big enough so that the air does not accelerate too much when being pushed through it.

Needs to be under 17meters per second or something. Try using WinISD and then check the rear port air velocity. You'll find as you adjust the port size, the curve will shrink or expand.

 

[supa_c 5,000+ posts]

Your port has to be big enough so that the air does not accelerate too much when being pushed through it.Needs to be under 17meters per second or something. Try using WinISD and then check the rear port air velocity. You'll find as you adjust the port size, the curve will shrink or expand.

heh, mines at about 24 MPS.

Not good, i need a retune

 

[jellyfish420 10+ year member]

check this out. it'll answer all your questions about port size and output.http://forums.caraudio.com/vb/showthread.php?t=69944