I am gonna be making a large system en closer in the z. I usually use 19mm MDF but I am trying to keep the weight down as much as possible. I was thinking about fibreglass but dont know whether it compromises the sound quality?

Any other ideas??

Use a combination of both.

 

The best sound quality comes with the thickness of the box the sub is in.

It's hard to keep weight down and have the best sound. So I'd go for a basic ply frame followed by fiber glass moundings.

So, make a box for each sub and then a fibreglass shell covering them all with 6x9's in shell? would fibreglass be strong enough to hold the amps?

Caould I use thinner wood?