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.

The best room I ever heard simply used 8 by 2s instead of 4 by 2s, and with half the spacing, then used double thickness of drywall, and obviously treated the drywall. I suspect the amount of MDF you would need would be very expensive compared to other viable options.

Rives -

I have a concrete basement room I am going to finish/spruce up for a listening room, about 20x13x7-8 or so. Where can one find that Owens Corning panel material you have spoke of in the past? I was thinking put up some reasonably absorbtive panels (such as that stuff ) with drapes over that, should cut down the liveness somewhat, and be a lot less work (and easier to redecorate w/ new draping fabric) than Drywall. Any thoughts, offhand?

thanks
-Ed

Ed: Why not have us design your room? Getting the material is not difficult, many building supply places have it or can get it. The trick is knowing how much to use and where. That's where we can help and give you a first class listening room using these types of basic materials--thus not breaking the bank.

I like OSB vs MDF idea and yes definitely use drywall to finish. Like Rives says you don't want to use too much rigidty and have the room not absorb.

If you have some specific question with detail I am able to give you some direction based on room dimensions and detail built into the walls. I will even do a basic RT60 calculation for your room with and without OSB/MDF and chart the axial mode that can be plotted for comparison against ideals. No room is perfect even after extensive planning and some tweaks are necessary. If your room is for HT the demand is less stringent because almost everything in HT is fake and loose, kinda like golden topping.

email me if you care to discuss

Rives - thanks for the idea - will take that into consideration and likely be contacting you in the somewhat near future.
thanks
-Ed