Ok, im building a 2x12 cab out of scrap plywood. I have an Eminence Governer and Swamp thing. First, it was quite bright and had a lot of high overtones. I then put a speaker separater in and blanket pieces against the back panel. Wow, what a difference. It seems something I have done makes a big difference. The high overtones are gone. It has a more smooth sound but it is still able to hit the squeels when needed.

Im playing through the Bugera V55HD and a pod xt live with a Charvel with active EMGs.

I may post a pic but since it's just made out of scrap crap, it doesnt look pretty at all. Just my style
96 MIJ Jackson
Charvel DC 1 FR
PRS SE Custom 24
Yamaha FG730S
DIY acoustic
DIY mockingbird
Peavey classic 50 2x12