Building box,have question on ports

[tman]

Hey guys,

Im built a ported box for two JL10W5-D4 subs.
The specs on the speaker are:
Fs: 31.7Hz
Qts: 0.384
Qes: 0.402
Vas: 1.60 ^3
Xmax: 0.295

The box im building is 18*14*14 per chamber
IM using a Punch 800.2 to push them with about 200W to each.
The port dimensions it calls for are 3x10.75.
This port length seems kind of short to me for a 30-40hz tuned box?

Am i wrong here? What should the port dimensions be for a round port?
The box is already built so it dont have much room to play with for the length of the port.

Thanks,

Tman

[ShaunMac]

Are the 18 x 14 x 14 dimensions internal?
How many ports do you have?
What tuning freq are you looking for?

[tman]

The dimensions are external with one port per chamber.
Im not looking for SPL, im more into SQ cause its for daily driving.

Thanks,
Tman

[Trixter]

Assuming 3/4" MDF you have a 1.5cu' box

According to WinISD, 1.5cu' box with a 3" diameter port tuned to 35Hz would be 8" long. If it was 10.75" long it would be tuned to 31Hz.

[tman]

Yes it is 3/4 MDF. I guess i should go with the 35Hz huh? that sounds like a nice round number.


Thanks for the info guys!

Tman

[ShaunMac]

If you're more into SQ you might go with the 31Hz tuning freq.

[tman]

Ooops... that is what i meant to say!
Thnks,

Tman