PORTED or NOT PORTED?

[SHAZ325iSPORT]

hey guys im designing a bass box for my BMW 325 Convertible,its gona have a 12" JL Audio W7 1500 Watts RMS,right what i need to know is should i have the box ported or not ported?what will sound better,let me know guys because im half way through and need to finish off.Thanks

[Ziggy]

If it's half way through, have you already determinied the size / shape? It'll need to be different for a ported box, cf a sealed one... expect you already knew that, just thought I'd make sure!

[chu346]

Ported mate

Try and get the spec from jl audio and use slot ports to get the best out of it!


BTW its 750Watts RMS.

[Jos]

Always find that subs can be designed either to run ported or sealed. As a general rule I always try to go for sealed design 1st for a couple of reasons:

1) the box is smaller
2) bass response is faster and tighter on sealed than it is on ported.

How can you be half way through when you haven't decided what enclosure type to use? The most important factor with a sub is the SIZE of the enclosure, and these are different depending on what type of enclosure you are using; sealed, ported, 6th order, bandpass..

As the 12W7 Thiele/Small Parameters are:

fs: 27.23Hz
Qes: 0.514
Qms: 7.807
Qts: 0.482
Vas 2.33cu. ft.
Xmax: 29mm

This would point toward a sealed enclosure as fs < 35Hz, Qts > 0.40 and Xmax > 4mm

Depending on what sort of response you want the box can be anything from 2cu. ft. to 1.3cu. ft. in size. A Qtc of 0.707 (flat repsonse would need a sealed box of 2.023cu. ft. A slightly higher Qtc giving a slight boost in bass response would need a box 1.328cu. ft.

Depends what you want really, I always go for flat response as you can tweak it later, whereas its harder work to correct the speaker failings after the fact..

FYI JL Audio say 1.375cu ft giving a Qtc of 0.792 in a sealed enclosure.

If you do want to do ported JL say 1.75cu. ft. with a tuning port of 32Hz slot type..although I would say 4.3 cu.ft. and a tuning of 22Hz.. but thats just me..

[carlos_320i]

I am running 2 15" jl subs and I have always had jl subs in my other cars and they have always been a seeled box as they dont like to be ported and you will blow the sub if it is wrong