I made that observation about the MDF shelves before I ever built a speaker. I built my first speakers from MDF cause that's what everybody does. Continued with it 'cause that's what everybody does and it's cheap. works well and holds veneer well. I did build the Fostex horns from plywood but they sounded so different from what I was used to. Seems more and more speakers DIY and commercial get built with solid wood or plywood and solid or MDF and solid or billets of aluminum and carbon fibre, etc.,....... I come back to the absolute fact that my Cambridge CD player which had an overall laid back and mellow presentation sounded like an AM radio on the MDF. HMMMMMMMMM.............