MDF is used primarily to reduce cost and is easy to work with and cheap and easy to obtain. Moisture affected like real wood is and not very durable and easily crushes at corners.
HDF ordered a full inch thick is dead an inert and a great choice for better controlling the box from resonating or flexing and is very easy to machine and glue and provides better weight to the cabinet. This is used in better built cabinets and by some for the front baffle only. Consciderably less affected by moisture and change of temperature.
17 mm Grade A A Birch Ply offers great control over flexing and resonating ( think turntable plinth) and is the easiest to work with but as a traded commodity is more expensive but offers superior results when braced properly as any choice needs to be. Not affected by moisture and humidity changes. Cuts and machines wonderful with nice clean chip free edges. Tone seems to be better when used for speaker boxes( subjective ) but as you were rightfully cautioned braced well, but all good results require that in your design.
My suggestion and what I have done with best results. Build them from Baltic Birch cross brace them internaly as much as your design allows. Don,t brace them from side to side, brace them with a box frame (like a picture frame) dadoed into place. Then cover them in solid wood that serves to further stiffen the box and no longer having to worry about what wood to choose for sound characteristics (other then weight) only astetics you can have whatever you want and not worry about chipping or ding corners of paper thin veneers. At about a 100 bucks a sheet not knowing how big your speakers will be and how much you will need if cost is a factor and you would rather put more towards even better drivers the HDF is your best substitute but at 1 inch thick and very dense it is heavy to work with.
Cheers and happy building!
HDF ordered a full inch thick is dead an inert and a great choice for better controlling the box from resonating or flexing and is very easy to machine and glue and provides better weight to the cabinet. This is used in better built cabinets and by some for the front baffle only. Consciderably less affected by moisture and change of temperature.
17 mm Grade A A Birch Ply offers great control over flexing and resonating ( think turntable plinth) and is the easiest to work with but as a traded commodity is more expensive but offers superior results when braced properly as any choice needs to be. Not affected by moisture and humidity changes. Cuts and machines wonderful with nice clean chip free edges. Tone seems to be better when used for speaker boxes( subjective ) but as you were rightfully cautioned braced well, but all good results require that in your design.
My suggestion and what I have done with best results. Build them from Baltic Birch cross brace them internaly as much as your design allows. Don,t brace them from side to side, brace them with a box frame (like a picture frame) dadoed into place. Then cover them in solid wood that serves to further stiffen the box and no longer having to worry about what wood to choose for sound characteristics (other then weight) only astetics you can have whatever you want and not worry about chipping or ding corners of paper thin veneers. At about a 100 bucks a sheet not knowing how big your speakers will be and how much you will need if cost is a factor and you would rather put more towards even better drivers the HDF is your best substitute but at 1 inch thick and very dense it is heavy to work with.
Cheers and happy building!