I have older pioner 12 inch subs, I wanted to put them on a mdf board in the rear hatch are. Were there is a hole, mounted facing at the hatch glass. Any one do this or am I better building a custom box.

 

Build a box. It won't sound good if it's not sealed.

 

Even if they are not sealed enclosure subs. I could build a ported box, but how do you figure out the port tube diameter and lenght?

 

Goto the tutorial section on www.JLaudio.com. They have equations for building a box w/ or w/o a port.

 

My subs were free air; they sounded great. Every car audio guy was amazed at how good they sounded - but, after 6 years the MDF plate board broke, and they're in my basement in a pile. My next system will just have a single 12 sub in a sealed enclosure. So you can go for the plate over the hatch if you've already got the subs, but you'll definately get the best sound from an actual enclosure.

(I bought my dual 12" plate from JCWhitney, I think it was $40 or so.)

 

do you have a model# for the sub?

 

I used to have 2 Pioneer 12" free air subs in a sealed box... they actually sounded great! Not sure if they would have sounded better if I ported it... but for the $$ it was worth it.

 

free air subs are designed for massive sealed enclosures.

hence why you can put them on a decklid and make your trunk the box.

<==isnt sad that there are very few IB subs made.