Originally Posted by mijotter
Oh wow so what is the optimal depth for said project? Is ductboard even a good material to use?
If you are sticking with strictly DIY simple absorber then typically 2" thick OC703/equiv + 2" air gap will suffice to not EQ the sound, you may not get all the 250hz to 400hz but that is trade off to room encroachment.
By the "book", if you do have space then 4" thick with 4" air gap will ensure you do not EQ the lower end of the bass for a true broadband absorber that works above the typical Fs transition freq of 250hz in HT sized small acoustic spaces......
You want to only apply the treatments where needed, not blindly following some guide.
The "mirror trick" is a good starting point to plan from.
Minimal absorber acoustic treatments to keep as much sound energy in your room is the overall goal, while they do their job where needed.
Me, my next foray into DIY treatments may step up to DIY BAD treatments for my side walls....
I'll do that when I also upgrade from floorstanding dome tweeter to baffle wall CD waveguide speakers, circa mid-2015 when I also move up to 4k PJ.
Have fun, it's a hobby after all, not world peace.