How low do we need to absorb? And how?

[TomM]

Do more layers of 705 absorb even lower frequencies?

Or is it the larger the air-space behind the absorber?

Or both? Or neither?

Why not use 10 inches of 705 in all corners to smooth out the freq. response of the low end even more. Is it just a matter of losing space?

Is the concern more of just a trade-off of making a room too dead vs. flat frequency response?

I was thinking of making some floor to wall traps that have several layers of 705 with a laminate wood floor top.... to flatten the low end out more without killing the highs at all. This would be in addition to regular bass traps in the walll to wall corners and then some 703 at first reflection points.

[AVare]

A little to answer your questions directly. Hopefully this will help.

All porous materials absorb low end the thicker they are. What is also important is the postion in relation to the air velocity. As frequncies get lower, denser materials start to reflect sound, so lighter materials are better and (usually) cheaper. 703, SAFB type material, etc will do a better job than 705 for low frequencies using thick material.

The amount of absorption can be too much. Forunately as small room acoustics work out it is difficult to build too much low end absorption into a small room.

Good luck!
Andre