Novice ?'s about vented enclosures

 

New member
Username: Jaysend

California

Post Number: 9
Registered: Apr-04
I am building a vented enclosure for 2 jl 12w6s.
JL has a diagram for a vented enclosure and it says to double the volume and ports for 2 subs.
Now my questions are:
1.Does this mean two seperate ports, each identical to the dimensions listed for one sub, or one long port with double the length?

2.Also my box is going to be a much different shape (but same volume) than the one jl recomends. Can I still use the same port dimensions?

3.Does any one have the formulas for computing tuning frequency?
Thanks in advance.
 

New member
Username: Jaysend

California

Post Number: 10
Registered: Apr-04
Another question is that with 2 subs the wiring options say that I can run 6ohm load in series or a 1.5 ohm load in parralell. How the heck do I figure out an amps power rating with that? Amps generally only state 1 ohm 2 ohm and 4 ohm not 1.5 or 6
Thanks.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 2481
Registered: Dec-03
1.Does this mean two seperate ports, each identical to the dimensions listed for one sub, or one long port with double the length?

example: if for one sub, the box is 2cu ft, with one 4" port, 7" long, then for two subs, the box will be 4cu ft, with one 4x7" port on each side.
its just like building two boxes and sticking them together.

2.Also my box is going to be a much different shape (but same volume) than the one jl recomends. Can I still use the same port dimensions?

yes, port volume is based on enclosure volume.

3.Does any one have the formulas for computing tuning frequency?

of course
http://www.the12volt.com/caraudio/boxcalcs.asp

you have two dual 3 ohm coil subs.
JL does this, apparently, so you have to use their amps which have regulated outputs if you want easily figured power outputs.

Anyway you're using two subs. wire them for 6 ohms, then put them in parallel for a 3 ohm load.
then, take the mono amp power ratings at 4 ohms and at 2 ohms, and figure the output @ 3 ohms is half way between the two. then divide by 2 and you have the power per sub.

example:
amp is rated @ 600w x 1 @ 4 ohms and 1200wRMS x 1 @ 2 ohms.
at 3 ohms, the amp would produce a total of 900 watts.
that'd be (divide by 2) 450 watts RMS per sub.
 

Bronze Member
Username: Jaysend

California

Post Number: 11
Registered: Apr-04
For the box could I also use one port with the same height and width but double the length?

Also on the subs, I believe that the w6's are dual 6 ohm voice coils. According to the owners manual I can run 2 at 6 ohm in sereis or at 1.5 ohm in parallel. SO I guess that would mean I could run them in parallel and figure on a power rating between 1 ohm and 2 ohm or just get the jl 500/1 which is 500 watts from 1.5 ohm to 4 ohm.
Or is there another way to wire them to get a 3 ohm load?
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 2526
Registered: Dec-03
that's dual 3 ohm coils
use that calculator at bcae1.com or the12volt.com for the ports
makes it simpler
you can specify the number of ports you want, and their inner diameter

dual 3 ohm coils with two subs
wire coils in series for two 6 ohm subs
wire subs in parallel for 3 ohm load
or vice versa
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