With the panel on wood panel traps required to resonate, these panels are said to be effective about 1.5 octaves.

Has anyone tested the Q of having different panel materials?

Would a less stiff (but same weight) material make the Q lower?

How can I build a trap and test it to try some ideas on how to broaden the useful bandwidth? Someone please answer this, let's not skip by this.

On the site, 1/4" ply is used for the deep bass trap. Have you ever tried a thicker panel, and if so the result?

Regarding membranes like MLV for corner traps in smaller rooms:

If a broadband is placed in front of the MLV (with air space - not touching) , would one combine the benefits of both designs ( trap and broadband)

What is the typical MLV weight used?

As for having broadband in front of panel traps, any construction tips (diagrams) on how to do so would be appreciated.

thanks
GCJ

Those are all excellent questions!

I have not experimented with this because it's very difficult! The best way to test one trap is with an impedance tube, which you'll find in an acoustics lab. And that's expensive. Otherwise, the only way to know is to build a bunch of traps and see what happens to the response and ringing when you measure a room. There may be a direct way to measure the center frequency and Q of one trap, but I'm not aware of how. A friend of mine suggested using a laser pointer bounced off the front surface. He's actually going to try that on some wood panel traps I made years ago. If he's successful I'll let you know.

The traps I made years ago addresses your other question. As an experiment my partner and I made four traps that we hoped would peak around 50 or 60 Hz. These are the traps my friend will try to measure with a laser. I think we used 1/2 inch plywood, and the box is 2 feet wide by 7-1/2 feet high. One problem is heavy plywood is stiff, and might not vibrate freely enough when only two feet wide.

RPG uses MLV (or something that looks similar) for their Modex Corner traps. In theory that could be better than wood because it won't be affected by the edges being attached to the frame. That is, when a wood panel is secured to the frame, the edges can't vibrate at all. Versus MLV that can vibrate right up to the edges. I hope I'm saying this clearly enough.

Finally, you can place rigid fiberglass in front of a membrane, but it shouldn't touch the membrane. I posted photos of that in my studio just yesterday:

http://forums.musicplayer.com/ubbthreads.php/topics/2119361/Build_a_Better_Bass_Trap

--Ethan