Front material of panel traps. Is MDF ok?

Ethan uses plywood. Is it ok to use 4mm thick MDF instead? About the back: Can I use a thinner back plate (I'm building portable units), say, 8mm? I'm using 12 - 18mm for the sides and top.

Pasz, > Ethan uses plywood. Is it ok to use 4mm thick MDF instead? < I'm sure it's okay, but you may need to re-determine the equivalent MDF thickness factoring in the difference in weight between plywood and MDF. > Can I use a thinner back plate < No, the back should be rigid and massive so as not to flex when the front panel vibrates. It may be possible to come up with a two-panel system that works, but I don't know how to calculate that. When someone asks about making wood panel traps that are portable, my standard advice is to make rigid fiberglass bass traps instead. If you can't build them onto the walls, then there's little reason to use that design at all. --Ethan

Ah, great! The man himself ;).

Ethan Winer wrote:

Pasz, > Ethan uses plywood. Is it ok to use 4mm thick MDF instead? < I'm sure it's okay, but you may need to re-determine the equivalent MDF thickness factoring in the difference in weight between plywood and MDF.

The MDF is in the workplace now, not near where I'm now so I'll have to check what type/brand it is later, so I can check the weight (there are different types/brands right?). What weight should it be for the deep bass trap and high bass trap? If the 4mm MDF turns out to be the right weight, can I use it for both the deep bass and high bass trap? 4mm is the thinnest I can get.

> Can I use a thinner back plate < No, the back should be rigid and massive so as not to flex when the front panel vibrates. It may be possible to come up with a two-panel system that works, but I don't know how to calculate that. When someone asks about making wood panel traps that are portable, my standard advice is to make rigid fiberglass bass traps instead. If you can't build them onto the walls, then there's little reason to use that design at all. --Ethan

I just decided NOT to make portables, so I'm mounting them on the wall (gypsum walls with 9cm insulation behind them) with toggle bolts. :)

Pasz, > I just decided NOT to make portables, so I'm mounting them on the wall < So why not just use 1/8 inch and 1/4 inch plywood as described in the plans? --Ethan

Ethan Winer wrote:

Pasz, > I just decided NOT to make portables, so I'm mounting them on the wall < So why not just use 1/8 inch and 1/4 inch plywood as described in the plans? --Ethan

I already had the 4mm MDF :). But if it's not suitable, I'll get the plywood anyway. Another question: On deep bass trap is covering up a power outlet. Will mounting the power outlet box onto the panel (caulked airtight) be ok or would the panel lose its function (I think I already know the answer but I just have to ask)?

Pasz, > I already had the 4mm MDF :). But if it's not suitable, I'll get the plywood anyway. < Here's what you can do: Weigh a sheet of the MDF, then find pieces of 1/8 inch and 1/4 inch plywood the same size and weigh those. If the MDF is close to either plywood thickness, then it will be okay as a substitute for that thickness. > Will mounting the power outlet box onto the panel (caulked airtight) be ok < It will prevent the panel from vibrating, but it's position in the panel can minimize the damage. When I built a pro studio in the late 1970s the entire control room was lined with alternating traps as described in my article. We built outlets into some of the traps, but we put them lower down than usual so they wouldn't prevent the majority of the panel from vibrating. --Ethan