What is your favorite material for loudspeakers?

Interesting. . . in most cases, Baltic Birch is not from the Baltic region. . . it usually denotes a somewhat hiher grade birch ply from Russia, Bielorus, or China. Finnish birch instead. . . is a different kettle of fish. One of the highest grade materials I have found is from Finnish fabricator UPM, which can be sourced in thicknesses up to 50MM:
http://w3.upm-kymmene.com/upm/internet/cms/upmcms.nsf/$all/af4c54532110776dc22570ba00304034?OpenDocument&qm=menu,4,5,1&smtitle=Plywood
Material uses outdoors bonding agents and has 21 plies on the 1 inch thick product. This appears to be higher grade material than what is usually called 'baltic' or 'marine' plywood. G.

I bought some Hawaiian Koa veneer for the ProAc 2.5 clone project I have planned.

Solid wood all the way. My Audio Note speaker cabs are custom made using Indian mahogany which is the same species as Cuban mahogany. Water stain, shellac and Sutherland Welles tung oil.
More volume...more natural..more bass...more tweet...kind of like a great amp upgrade.

The Baltic we use is Finnish I buy by the pallet to save $. If you source plys from most home centers its Chinese and lamination on this ply are terrible. Sometimes I can pull Chinese plywood apart with my hands!!!. Ive tried MDF ply, HDF ply and others in layers still to me Baltic and veneer with French polish gives best results for my loudspeakers. But my good friends a TT nut he uses layers on his plinths. I use aged hard rock maple for bracing this gives best tone. I have build solid hard wood cabinets but most split after a bit of time ,if I use hard woods I use over ply. Thank you for the posts. And happy listening.

Johnk,

Your thread has got me thinking about the possibility of building the ProAc 2.5 clones using Baltic Birch plywood instead of MDF with veneer.

I know this would alter the sound of the speakers from their original intent. What are your thoughts on the sonic influence of this wood for box construction?

Thanks,
Dean