Just finished installing a new door speaker baffle made of HDP or High Density Polyethylene. Previously I was utilizing a 1/2" peice of MDF board, but decided to switch to the other material for structural and cosmetic reasons. The HDP material is very dense and solid...because its a type of plastic it resists water better than MDF too. MDF is layered and could be prone to cracking/warping when exposed to water...HDP is one form and does not suffer these attributes.

 

Very nice. So did it make an audible difference?

 

There wasn't much audible difference really, although the material performs equal to if not better than the MDF peice I had installed. The main reason I chose to use HDP material is for cosmetics purposes(and of course its water-proof properties)...I found that an upholstered peice of MDF does not look as natural as the plastic material...and found it more practicall than stuffing a peice of wood in an autombile door, if I can put it in those terms. ALthough this stuff doesn't come cheap costing about $50 for a 2ft X 2ft peice. I was able to find a scrap peice for free.

 

Most plastic shops have cutoffs lying around, many of which are large enuf for car audio projects, and they are always discounted.

 

I'll have to find a local shop around here that might have some scrap peices for sale.