Quick question regarding the 38% rule (in terms of room length).

[Fox Mulder]

I've got 6 inch absorbers behind my monitors. Do I calculate from them or from the the actual wall?

 

[TheDriller]

unless the absorbers take up the entirety of the wall, no, calculate from the actual wall itself.

 

[Wisheraser]

Also, remember that 38% is just a starting point. If things aren't quite to your liking there, try moving a little forward or a little back until things seem a bit more balanced. Don't forget to take measurements along the way too (like described here: http://www.realtraps.com/art_measuring.htm ) so you know if the changes you make are actually improving your rooms response.

 

[pitoga]

It's measured from the hard surface, therefore the Wall. Even if the whole wall has absorbers it's still measured from the hard surface.