port size

[blazeplacid 10+ year member]

Im planning on builing a box for 2 Re se 10" subs

im going to build it right at 2 cubes because of space.

My main question is what size port to use.

the box is 27"x13"x13"

a 4" round port would be 12" and give me 33HZ

a 3" round port would be 6" and give me 33hz

which is "better" longer and larger port or smaller and shorter?

Im not to worried about port noise cuz it will be in the trunk.

thanks

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[MONSONwarrior Premium Member]

larger, longer.

 

[T3mpest 10+ year member]

Even if you dont' "mind" port noise realize that the reason a ported box is louder, at least in part is because the port adds SPL do the system, it moves air just like a speaker does. A small port isnt' capable of moving as much air as a bigger one. At some point the air inside the port begins to compress to much due to high air speeds. This causes the port to acoustically compress. This will end up reducing your actual SPL as when you begin to push the port it stops working, the same frequencies you wanted to boost with your port are now being cut compared to everything else at higher volume levels. It was as simple as just getting the tuning right we coudl all use 1" pvc and easily get any tuning we wanted. All things considered I consider it more critical to get the sizing correct more than tuning, at least if you plan on pushign your system hard like most CA fans do. A tuning difference of a few hz isn't a big deal as cabin gain makes things a little bit unpredicable anyway. Keeping the system linear from low volume to high is important. If you can fit the bigger port and still give your subs reasonable airspace go for it. How much power do you have on tap?

 

[bubbagumper6 5,000+ posts]

Even if you dont' "mind" port noise realize that the reason a ported box is louder, at least in part is because the port adds SPL do the system, it moves air just like a speaker does. A small port isnt' capable of moving as much air as a bigger one. At some point the air inside the port begins to compress to much due to high air speeds. This causes the port to acoustically compress. This will end up reducing your actual SPL as when you begin to push the port it stops working, the same frequencies you wanted to boost with your port are now being cut compared to everything else at higher volume levels. It was as simple as just getting the tuning right we coudl all use 1" pvc and easily get any tuning we wanted. All things considered I consider it more critical to get the sizing correct more than tuning, at least if you plan on pushign your system hard like most CA fans do. A tuning difference of a few hz isn't a big deal as cabin gain makes things a little bit unpredicable anyway. Keeping the system linear from low volume to high is important. If you can fit the bigger port and still give your subs reasonable airspace go for it. How much power do you have on tap?

This. I would go with at least the 4"

 

[blazeplacid 10+ year member]

Wow thanks for all that info in that post