thought I would bump this. No one wanted to take a stab at the tuned trap question.
I found plenty of info on tunning a helmhotz and even found a calculator. Have read ethans stuff on it as well but found no detailed instructions on calculatiing volume and membrane density thickness etc and how dense to fill the device with insulation. If you know of a DIY web site or book on how to create and tune these I would apreciate your help.
I am not looking to tune the entire room. meaning, not looking to have a perefectly balanced space, but rather employ some strategicly placed tuned traps to deal with the 70-80hz null at my mix position without having to employ eq's which add other issues with headroom and phase.
2' thick broad band in my room is not an option. Trying to avoid spending thousands on RPG modex devices.