I just decided to build the bass traps described in Ethan's excellent on-line articles.But I have a couple of questin that rised.
I have just finshed rebuilding the room that is dedicated to my Hi-Fi audiophile set-up (all DIY I must say).The room is 5,2 metre long ,4 metre wide and 2,8 metre high.It is quite empty ,now except for thick carpet on the floor and one armchair and sofa.The music sounds terrible now (typical for empty rooms).I'm planning to build a couple of low bass,mid bass and mid high absorbers,and then ,after I have enough absorbtion I plan to add Skyline style diffusors (I found local styroflex company that will produce them for me quite cheap) to take care of the first reflections (side walls and front and back walls).
These are my questions:
In those plans the actual back of the trap is wall itself.Can I glue the playwood in place where the wall is and make the trap more movable.
Also how important can be the thickness of this back wall and how steady does the trap have to be mounted to the wall (can it be hang on one nail like a painting for example)?
Also can i just lay the trap made that way anywhere I want,like just lay it on the floor by the wall? Will it work the same that way?
Today I went to wood store and I found that the wood panels of specified in the plans dimensions are quite hard to find.It may be coused by the diffrance in measuring systems inches-centimeters.
4 inches is 10 centimeters,which I can't find.They have 9 centimeters.2 inches is 5 cm.,they have either 4 or 6cm...etc.
How important are the actual dimensions of the spacing and air gaps in the plans?
I have many questions that I would like to get the answers for,but also I would like to thank Ethan for sharing his knowledge with us.

Bartek

Bartek,

> Can I glue the plywood in place where the wall is and make the trap more movable. <

Yes, absolutely.

> how important can be the thickness of this back wall and how steady does the trap have to be mounted to the wall <

The back needs to be rigid enough not to flex. If you use at least 3/4 inch plywood, MDF, or particle board, it should work okay. It does not have to be mounted securely to the wall, but it must rest against the wall. Wood panel traps do not work well when spaced out from the wall. So make sure the back is right up against the wall.

> can i just lay the trap made that way anywhere I want,like just lay it on the floor by the wall? <

Again, it must be right up against the wall. And bass traps always work best near the corners. So you can lay them on the floor horizontally, but they should be against the wall and parallel to it. The corner between a wall and the floor, or the wall and the ceiling, is just as valid as a regular wall/wall corner.

> 4 inches is 10 centimeters,which I can't find. They have 9 centimeters. 2 inches is 5 cm.,they have either 4 or 6cm...etc. <

Small changes like that are okay. If you increase the box depth the center frequency shifts down a little. So as long as the change is no more than 10-20 percent you'll be fine.

--Ethan

In America, a 2"x4" is actually 1.5" x 3.5"
All lumber is sold according to rough-cut dimensions. When it is dried, it shrinks quite a bit.

So the 4" side of a 2x4 will measure about 9 cm.

Phil

Phil,

> a 2"x4" is actually 1.5" x 3.5" <

Good point. Thanks for adding that.

--Ethan

Could you repeat this? This is important for Europeans like me trying to follow all the DIY issues. So usually one inch is 2,54 cm and when talking about lumber I have to substract 0.5 inch?
How about the U.S. switching to the metric system? It has got the advantage of being logical.

Cheers,
-Jules

Jules,

> when talking about lumber I have to subtract 0.5 inch? <

This has nothing to do with Metric versus Imperial units of measure.

When a 2x4 board is first made it's really 2 by 4 inches, and you can even buy them that way. But the edges are rough. A second step at the lumber mill shaves off a little more on all sides to make a smoother finish. And that's what reduces each dimension by about 3/8th inch.

--Ethan