Dead / Non-Resonant Speaker Cabinets

Today, most mainstream speaker manufacturers strive for a 'dead' sound from their speaker cabinets. They want the speaker box to interact as little as possible with the speaker itself, and they use a number of techniques to accomplish this. If building speaker cabinets yourself, you can use these ideas too: start with some beefy, high-grade 3/4 inch plywood and use internal bracing in the seams of the speaker cabinet whenever possible (some speaker designers actually use two layers of plywood for the front of the speaker to cut down on resonances further).

To cut down on internal standing waves, some speakers have no parallel walls. A cheaper and easier way to deal with standing waves is with internal sound absorption (usually in the form of 1 to 2 inch thick fiberglass batting on the inside back and sides of the speaker box for ported designs and poly-fill material to stuff the box if it's a sealed design).

*If you REALLY want dead speaker enclosures there's always concrete.