Space between the sound absorber and the wall

[Maverick]

Is it generally a good idea to add some space between the wall and the sound absorber when you hang it, if so, how much space. Or is it better to just set it flush? Thanks

[Ethan Winer]

In theory, the ideal air gap is equal to the material thickness:

http://www.ethanwiner.com/acoustics.html#air%20gap

--Ethan