[Jose R.]

Jose,
I think you have me mixed up with Rick Craig.....he has built many a line source speaker.

Oops .... sincere apologies, should read more carefully 

Regards

Jose

[Tyson]

Fully active - very nice!!  If you ever get a chance, you should try out a couple of tube amps on you mids and highs - in my experience tubes match very, very well with ribbons and planars in a fully active setup.  I know you lose the "all digital" chain, but it might be worth it - tubes and ribbons are breathtaking together.

[Ric Schultz]

MDF is resonant.  If you use 1, 2 or three layers of undamped regular MDF then you will hear noticeable colorations.  However, if you use highly refinded MDF (Rangerboard, Plum Creek, Medite 3D) and you use a viscoelastic damping glue like Green Glue or Swedac between the layers (at least 2.25 inches thick total) and you damp it with thick braces then you will be rewarded with a very low coloration baffle.  Aluminum may still be better...along with other hardwoods (solid birch and solid maple) and especially layers of bamboo plywood...but the wood products are easier to work with and mucho less expensive.