I also wanted to comment on HDF, since, you know, when do I not have a comment I need to make!\n\nI think the term is misused in the speaker business. HDF is Hardboard. When is the last time you saw 3\/4" HDF? I myself was really confused. I had heard that HDF was hardboard and then saw the term thrown around with speaker enclosures. I went to a local specialty shop and asked for HDF in a 3\/4" size. The guy told me he would have to see if he could order that, as it wasn't stocked. Not only is it not stocked, I had to order an entire lot because it needs to be made up in sizes greater than 1\/2". I asked what HDF was, thought maybe I was confused. Turns out, HDF is hardboard and is rarely if ever used in thicknesses of 3\/4" or more. \n\nA lot of speaker manufacturers claim to be using HDF instead of MDF, but when you look at the raw enclosure, it sure looks like MDF. My understanding is that, as expected, MDF and HDF are basically defined by their density and as such, there is an accepted range between the particle board, MDF, and HDF. The primary differentiator is particle size of the wood byproduct used to produce a panel. I sat on the phone with the manufacturer (who actually makes the boards in Canada, and ships to here) and sent him emails of what I was reading, and what I wanted it for. He came back and told me that he thinks that the manufacturers probably are buying a high-grade MDF that is on the denser end of the scale and calling it HDF because it probably falls onto the low end of the HDF scale. This high-grade MDF is not only plentiful but even in stock locally. He told me that 3\/4" HDF, as defined by the industry, is usually only made on an as needed basis for specialty purposes, often like CNC carving or furniture. He told me that it nearly doubles the weight of the board. He also told me that while the primary differentiator of MDF and HDF is the density, it does impact how they are made, with MDF having more fillers, like wax. \n\nIn other words, HDF is masonite and masonite is really hard to find in 3\/4" sizes. If anyone knows differently, I'd love to know where you got your info and how I can obtain HDF in such a thickness. From the week I wasted investigating it, I left concluding the term is used wrong by speaker companies.