1. ## Tuning?

I have a box with 2 cubic feet and 2 11"x4" round ports, can you guys help me with what its tuned at? Or help on where to go to figure it out?

Thanks

2. ## Re: Tuning?

If you can do math failry well by hand, then I'd do this...

Where Av is the cross-sectional area of the port (in square inches),
Lv is the length of the port (in inches) and
Vb is the enlcosure's net volume (in cubic inches).

3. ## Re: Tuning?

is that 2 cubic feet net, like after port and sub displacement, or total? If you it is net, minus sub displacement and assuming you are using 1/4" sched 40 PVC, you will be tuned at 48.22Hz. That number will go up after mounting a sub in the enclosure unless you plan to invert. I hope that is in the neighborhood of where you wanted to be.

Also keep in mind, tuning will drop considerably after loading and it is interacting with it's surroundings. Must designers tune about 10-13% high purposely to compensate for this. Check JL's website if you are ever curious about this. If you run the numbers for their recommended vented boxes for any of there subs, you will find that what you calculated is a lot higher than what the web site says you will be tuned at.

4. ## Re: Tuning?

Thanks for the help, I am going to check my measurements/sub dispacement and double check.

5. ## Re: Tuning?

Originally Posted by j3bus2k3
If you can do math failry well by hand, then I'd do this...

Where Av is the cross-sectional area of the port (in square inches),
what exactly is "cross-sectional" area?

6. ## Re: Tuning?

Originally Posted by nVRuckus
what exactly is "cross-sectional" area?

Port Area.

7. ## Re: Tuning?

Originally Posted by LuNaTiC
Port Area.
Precisely. For a slot or rectangular port, it would be Height * Width. For a PVC style port it would be Pi*r^2...

nG

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