Spacing 6"bass traps 6" off a stud wall, waste of effort?

[danbronson]

Seems to me spacing the traps from the walls would make sense if they were placed on a concrete wall or something. A concrete wall would reflect 100 Hz and lower since it's so dense, right?

But a wall that's nothing but 1/2" drywall and 2X4 studs like the interior walls of my basement studio? I have a feeling any frequency that deep would just keep going past the wall, so spacing the absorption off the wall wouldn't do anything.

If I'm right, this will save me a little effort!

Am I right or wrong? Why? Thanks!

[SaSi_SiDi]

I think that the drywalls shoule be having some sort of fiber material inside. To some extent they should act like panel absorbers of bad quality as a good quality absorber needs to have a small distance between the fibers and the panel.

If they don't have anything in the cavity they should be resonating badly and be part of your problem... I think.

The drywall by itself is certainly reflecting most of the low frequencies. It does show some absorbtion in the low frequencies, like 0.2 or something in contrast to 0.02 of plastered concrete walls but that is hardly enough. It's a start though.

The low frequencies will be reflected mostly from the drywalls. The standing waves will have a null energy on the surface of the wall (like any room boundary) making the bass trap more effective if it is at a distance from the wall.

Bibliography shows a 4" trap spaced 4" to be pretty efficient. However, a 6" trap at a 6" distance - if you have that to spare would be even more efficient in the lower frequencies where you need as much as you can get.

I am planning to mount such traps at such distance in the front wall where I have a 5.6m length and need to fight a 30Hz mode and further higher harmonics.

[Weasel9992]

Originally Posted by danbronson

Seems to me spacing the traps from the walls would make sense if they were placed on a concrete wall or something. A concrete wall would reflect 100 Hz and lower since it's so dense, right?

But a wall that's nothing but 1/2" drywall and 2X4 studs like the interior walls of my basement studio? I have a feeling any frequency that deep would just keep going past the wall, so spacing the absorption off the wall wouldn't do anything.

If I'm right, this will save me a little effort!

Am I right or wrong? Why? Thanks!

Definitely worth the time. You're right...the drywall will act as an absorber down low, but the panel will work much more efficiently in the higher part of the low end (70-250Hz) if the panel is spaced off the wall.

Frank