Thread: New sound setup.

schmexy^3

What caps? i see the one on the right is a 1/2F (lightning audio?), but what about the other one?

Any plans for a carputer

Is there a reason you used plywood for this project?

Page 12 of the October 2007 issue of Car Audio and Electronics:

Q: What are the pro/cons of using Baltic birch plywood vs. MDF in making subwoofer and speaker enclosures? I have access to both, but my father, who is a professional cabinetmaker with over 30 years of woodworking experience suggested plywood over MDF for strength and weight reasons. Any information from your experiences would be much appreciated. - Bryan Haglund

A: Your father sounds like a typical professional cabinetmaker. He's entirely correct, since he qualified his choise by the appropriate reasons - weight and strength. Let's establish one key thing - normal plywood is not acceptable, but Baltic birch (sometimes called "Russian Birch") plywood has been a staple of professional stage and touring cabinets for decades. Baltic birch plywood is manufacturered in a similar fashion to regular construction plywood with a couple of differences. Baltic birch is often seven- or 11-ply (layers) while sheathing plywood is only three- or five-ply, and uses fir instead of birch. The Baltic birch ply-wood is compressed resulting in a composite that's much stronger and lighter than MDF, making it ideal for travel and rock 'n' roll abuse.

So why does the speaker manufacturing and car audio industry use MDF? One key advantage to MDF is it's sheet density. A square foot of MDF is heavier than an identically sized piece of plywood of the equivilant thickness, and that translates to less acoustic resonance that messes with the proper reproduction of sound. If you open up a cabinet built with Baltic birch plywood, you find a maze of reinforcing braces that compensates for the lower density than an MDF cabinet would provide. After a baltic birch cabinet is fully reinforced to eliminate resonances, teh cabinet will weigh more than one made from MDF. So the big advantage of Baltic birch is still ruggedness.

MDF is also much easier to work with in the installation bay. It cuts like butter and accepts automotive-based fillers and paints much better than ply-wood. In the one-off world of custom car audio, we don't have the extra time to work with plywoods, which are better suited for assembly line situations where standardized treatments are used. Even so, lately a lot of high-volume home cabinetry is manufacturered with MDF.

We like all of the advantages of MDF for the car audio application. The one major downfall in the automotive environment to MDF is its tendency to turn into oatmeal when it gets soaked in water. Since MDF is really massively pressed layers of paper and glue, it will come apart since it doesn't have the strength fibers of plywood. Professional installers typically use fiberglass or epoxy resins to seal any cabinet that will be at risk of water exposure. This is critical because time is the enemy to bio-degradable wood product. In the Mobile Dynamics Escalade EXT, the cabinet was built using the standard installer practice: use MDF or Masonite for the flat sections and fiberglass for the curves. It's the fastest way to get a stunning product complete, but it does have a finite life span. About three years of shows later, the 0.25" MDF base began to delaminate at the corners. I had to cast a mold so I could build a replacement, but this time I made it from 100 percent fiberglass.