John Sayers' Recording Studio Design Forum Archive

Hi,
I am thinking about building 6 bass traps. Basically panel absorbers sized 2.4x0.6x0.3 meters (8x2x1 ft). Six of them to cover a 4m (12 ft) wall. Now I am going to need some broadband absorbtion and/or diffusion on te same wall. So, I have two options.

First is to mount a separate panel in front of the bass traps with the additional absorbtion/diffusion. This is not a problem for absorbtion, but diffusors are, I think, a bit of a problem (weight, resonating bits, etc)

or

Turn the bass traps around, with the membrane facing the wall but about 10cm/4 inches from the wall and some space between the individual traps. This way the diffusors/absorbers can be mounted on the back of the bass traps. There they don't interfere with the membrane, and my guess is that the bass trap (which only needs to work up to about 250Hz) will still work with the same efficiency.

My question is am I right in thinking that the bass traps will still work as planned, or does turning them around with the membrane facing the wall in some way change their behavior.

Thnx
Erik

Hi Erik, and welcome to the forum!

We'd need more details about your room to be able to help properly. Such as dimensions, purpose, construction, existing treatment, goals, etc.

But there's an issue with turning your membrane trap around. Normally, a membrane trap is sealed to the wall. It has to be air-tight in order to work effectively as a tuned device. If you turn it around, how do you seal the "back" (which is now the front)? If you put a piece of wood across it, then you now have two membranes on opposite sides of the same trap....

You could mount an absorption panel in front of the trap (facing the normal way), but you'd have to be careful to make sure that the absorption does not touch the front panel of the trap (the membrane).

- Stuart -

Ha Erik, welkom hier

First some semantics:
Basstraps : keep the bass at it's original position, like under speakers.
Absorbers : absorb soundwaves in the room. Low-end absorbers are typically mounted in the corners while broad-band can go anywhere like walls and ceilings. A low-end absorber is designed to catch the low frequencies in a room. Can't have enough of those. Broad-band are to catch a wider band of frequencies, like mid frq. The thicker the absorption, the lower it works.
tuned-panels : like the membrane panels you talk about, or Helmholtz. Designed to catch specific frequencies.

Sounds like you want broad-panels. In that case, do not add a panel in front or back. Keep the absorption material as "free" as possible. Adding just cloth will do. Making a frame around it will enforce the panel.

cheers.