Slat wall question

Thanks steve, Okay I will not try to create RFZ with angled slats since it will take too much space to be efficient. I will just put 703 to the side walls. About the cloth inside the slat resonator, what is actually consirided as cloth? Since you are using OC 703 which is a building insulation and i'm using Ecophon Akusto boards which are sold for acoustic purposes only. Those have a kind of cloth surface on other side. That cloth looks good in black boards what i have and is not meant to be hidden under cloth etc. Heres a link for the finnish product page: http://www.ecophon.fi/templates/eco_Normal_Long1a____10985.asp This is allmost the same product in english page: http://www.ecophon.co.uk/templates/eco_SystemPage1____8754.asp