Panel/Membrane Absorbers

[John Sayers]

I've found a company that makes a low frequency absorber and quotes the figures for it.

http://www.avlonline.com/studiopreszone.html

I've also found some figures here:

http://www.squ1.com/index.php?http://ww ... ption.html

Quote form page:

Membrane Absorbers
Membrane absorbers may be either flexible sheets stretched over supports or rigid panels, both mounted at some distance from the front of a solid wall. Conversion to heat takes place through the resistance of the membrane to rapid flexing and to the resistance of the enclosed air to compression. They will be most effective at their resonant frequency which depends upon their surface density (M) and the width of the enclosed space (b).

Fr = 60 / (M * b)1/2

Where:

Fr = The resonant frequency (Hz),

M = The mass of the panel per m² (kg/m²) and

b = width or depth of the air gap (m).

Hope this helps

Cheers
JOhn