MDF for walls in music listening room

Rives will probably have some thoughts on this. I would bet if you used MDF and drywall sandwiched with a constrained damping layer it would make the walls quite ridgid, which I would think might be great for lowering resonances and producing good low bass. I would also go to the ASC site, www.tubetraps.com, and also look at some of their room construction materials like Iso-Wall. Their method could be more cost effective. If I remember MDF is sort of pricey compared to dry wall. It all dependes on your budget. I am interested in sand filled walls. I know this is "somewhat" out there but I was in a small one at Magnepan that they use in the middle of the factory floor for testing panels. The silence in that room is a stunning contrast to the noise of the factory.

MDF with a damping layer and drywall over it will reduce resonances very much. However, there are still 2 things to be aware of. One is, how much do you want walls that don't resonate or give? A concrete wall doesn't give, and you can imagine the bass mode problems you have in a concrete room. On the other hand, walls that don't give do reinfoce the low end, so you can see this can be a good or a bad thing. In most cases, you don't want absolutely rigid walls unless you had the perfect room with built in traps to relieve the pressure and no parallel walls creating high Q factor bass problems. The second aspect of this is why to use MDF material, it is very expensive for such large surface areas. It's used in speakers as both structure and low resonance. For walls you don't need the structural support so, multi layered drywall with damping material between it can achieve nearly the same low resonance factor (unless you are using the mammoth of all subwoofers at high volumes--but under normal conditions) at a much lower cost.

Check with your Building Inspector before using only MDF (without an outer layer of sheetrock) as a wall surface. Building codes have a fire resistance requirement (minimun time to penetration) for walls that wooden paneling may not comply with. As an example, in my state standard plywood paneling must be installed over at least 1/2 inch sheetrock.