How thick should the front baffle of speakers be?

While I think solid construction is important, another sometimes overlooked thing is keeping the speaker from moving in 3 dimensions. A woofer can make the whole speaker rock back and forth. YMMV of course depending on the mass of the speaker, but a cheap tweak is often simply to add mass to the top of a speaker.

Tall skinny speakers benefit the most. It's pretty amazing.

Best,

E

3/4 inch plywood as used in vintage Altec's and JBL's will work just fine!

plywood works. I question the use of large drivers 10" and above that can shake the wood. I also question the method of attaching drivers to the face of a cabinet. Where is the technology? I feel let down. 

The 3/4" plywood used in the vintage JBLs probably did vibrate, but in a way that was pleasant to the ear.  For me, I am not particularly partial to speakers with heavy cabinets, but that's probably more to do with the overall design than the cabinet per-se.  

@soundsrealaudio- Martinis should be stirred, not shaken.  Just sayin' ;-)