Like who do you recommend? Post some links? You made DIY panels, frequencies did they post for the materials?
Owens Corning 703 rigid fiberglass is what I used. All manufacturers of insulation that's used for acoustics post the stats for absorption, but without knowing what someone wants to use or avoid (WRT shedding fibers, etc) it's hard to know what I should recommend.
I posted a link- look for their materials and check the info.
