"semi-reflective" broadband absorber

Hi, I know the topic sounds a bit strange (reflective absorber.. :roll:) , but I got the idea when I saw these pictures. http://www.cloneensemble.com/basstraps.htm Since there is often too much high absorption, when you use a lot of broadband absorbers, I thought it may be a good idea to get them semi-reflective at high frequencies. The idea is to put some thin slats (like here : http://www.cloneensemble.com/trappix/19_corner_1.jpg ) or thick paper in front of the mineral wool, which is only reflectiv to the highs/high mids. Here is a rough sketch: And here is my question: Is it ok to span fabric in front of them (...plain with no air gap between it and the slats - like in the picture), or does the fabric self absorb too much highs, so that the reflectiv parts gets useless? I hope that you got my point and that this question was not posted before. 8) best regards JCR