I'm having an issue with my subwoofer squealing/whistling. I'm not sure if it's a settings issue, or something actually wrong with the unit.
I have the Energy Take Classic II 5.1 system, but I replaced the front satellites with 2 Polk Audio RTi10 Towers with the AMP on the receiver set to BI-AMP.
I have a Denon 1712 AVR.
I ran the Audessey EQ Auto setup and went through all 8 passes, following this guide for my setup...http://batpigworld.com/index.html
I have my sub connected via a sub cable, with the volume set to 50%, and the Low-Pass Filter set to Max.
In my receiver settings, I set my fronts to small, and left everything else to the Auto Audesssey setup. The only setting I changed was my LFE+Main Crossover Freq. to 80hz, from 40hz, which is the THX recommended setting.
The squealing/whistling seems to actually be caused by a large of amount of air rushing out of the front port hole, and not the actual sub on the bottom of the box (down-firing sub). The whistling seems to happens with very loud, very low freq sounds.